Aryl Radical Endo Cyclization of Enamidines. Selective Preparation of Trans and Cis Fused Octahydrobenzo[f]quinolines

Journal of Organic Chemistry

Volumn 63, Issue 1, 1998, Pages 84-91

  Ripa, Lena ^a   Hallberg, Anders ^a  

^a UPPSALA UNIVERSITY   (Sweden)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0001803901     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo971158d     Document Type: Article

References (88)

1. For selected general reviews and books, see: (a) Curran, D. P. In Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon Press: Lonon, 1991; Vol. 4; pp 779-831. (b) Curran, D. P.; Porter, N. A.; Giese, B. Stereochemistry of Radical Reactions; VCH: Weinheim, 1996. (c) Giese, B.; Kopping, B.; Göbel, T.; Dickhaut, J.; Thoma, G.; Kulicke, K. J.; Trach, F. Org. React. 1996, 48, 301-856. (d) Jasperse, C. P.; Curran, D. P.; Fevig, T. L. Chem. Rev. 1991, 91, 1237-1286. (e) Motherwell, M. B., Crich, D. In Best Synthetic Methods, Free Radical Chain Reactions in Organic Synthesis, Academic Press: London, 1991.
2. For selected general reviews and books, see: (a) Curran, D. P. In Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon Press: Lonon, 1991; Vol. 4; pp 779-831. (b) Curran, D. P.; Porter, N. A.; Giese, B. Stereochemistry of Radical Reactions; VCH: Weinheim, 1996. (c) Giese, B.; Kopping, B.; Göbel, T.; Dickhaut, J.; Thoma, G.; Kulicke, K. J.; Trach, F. Org. React. 1996, 48, 301-856. (d) Jasperse, C. P.; Curran, D. P.; Fevig, T. L. Chem. Rev. 1991, 91, 1237-1286. (e) Motherwell, M. B., Crich, D. In Best Synthetic Methods, Free Radical Chain Reactions in Organic Synthesis, Academic Press: London, 1991.
3. For selected general reviews and books, see: (a) Curran, D. P. In Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon Press: Lonon, 1991; Vol. 4; pp 779-831. (b) Curran, D. P.; Porter, N. A.; Giese, B. Stereochemistry of Radical Reactions; VCH: Weinheim, 1996. (c) Giese, B.; Kopping, B.; Göbel, T.; Dickhaut, J.; Thoma, G.; Kulicke, K. J.; Trach, F. Org. React. 1996, 48, 301-856. (d) Jasperse, C. P.; Curran, D. P.; Fevig, T. L. Chem. Rev. 1991, 91, 1237-1286. (e) Motherwell, M. B., Crich, D. In Best Synthetic Methods, Free Radical Chain Reactions in Organic Synthesis, Academic Press: London, 1991.
4. For selected general reviews and books, see: (a) Curran, D. P. In Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon Press: Lonon, 1991; Vol. 4; pp 779-831. (b) Curran, D. P.; Porter, N. A.; Giese, B. Stereochemistry of Radical Reactions; VCH: Weinheim, 1996. (c) Giese, B.; Kopping, B.; Göbel, T.; Dickhaut, J.; Thoma, G.; Kulicke, K. J.; Trach, F. Org. React. 1996, 48, 301-856. (d) Jasperse, C. P.; Curran, D. P.; Fevig, T. L. Chem. Rev. 1991, 91, 1237-1286. (e) Motherwell, M. B., Crich, D. In Best Synthetic Methods, Free Radical Chain Reactions in Organic Synthesis, Academic Press: London, 1991.
5. For selected general reviews and books, see: (a) Curran, D. P. In Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon Press: Lonon, 1991; Vol. 4; pp 779-831. (b) Curran, D. P.; Porter, N. A.; Giese, B. Stereochemistry of Radical Reactions; VCH: Weinheim, 1996. (c) Giese, B.; Kopping, B.; Göbel, T.; Dickhaut, J.; Thoma, G.; Kulicke, K. J.; Trach, F. Org. React. 1996, 48, 301-856. (d) Jasperse, C. P.; Curran, D. P.; Fevig, T. L. Chem. Rev. 1991, 91, 1237-1286. (e) Motherwell, M. B., Crich, D. In Best Synthetic Methods, Free Radical Chain Reactions in Organic Synthesis, Academic Press: London, 1991.
6. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
7. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
8. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
9. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
10. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
11. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
12. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
13. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
14. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
15. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
16. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
17. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
18. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
19. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
20. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
21. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
22. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
23. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
24. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
25. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
26. For examples where the nitrogen and the second radical stabilizing group cooperate, see: (a) Colombo, L.; Di Giacomo, M.; Papeo, G.; Carugo, O.; Scolastico, C.; Manzoni, L. Tetrahedron Lett. 1994, 35, 4031-4034. (b) Colombo, L.; Di Giacomo, M.; Scolastico, C.; Manzoni, L.; Belvisi, L.; Molteni, V. Tetrahedron Lett. 1995, 36, 625-628. (c) Fang, J.-M.; Chang, H.-T.; Lin, C.-C. J. Chem. Soc. Chem. Commun. 1988, 1385-1388. (d) Fidalgo, J.; Castedo, L.; Domínguez, D. Tetrahedron Lett. 1993, 34, 7317-7318. (e) Pigeon, P.; Decroix, B. Tetrahedron Lett. 1996, 37, 7707-7710. (f) Rigby, J. H.; Qabar, M. J. Am. Chem. Soc. 1991, 113, 8975-8976. (g) Rigby, J. H.; Qabar, M. N. J. Org. Chem. 1993, 58, 4473-4475. (h) Rodrígues, G.; Cid, M. M.; Saá, C.; Castedo, L.; Domínguez, D. J. Org. Chem. 1996, 61, 2780-2782. (i) Takano, S.; Suzuki, M.; Ogasawara, K. Heterocycles 1990, 31, 1151-1156. (j) Takano, S.; Suzuki, M.; Kijima, A.; Ogasawara, K. Tetrahedron Lett. 1990, 31, 2315-2318. (k) Yang, C.-C.; Fang, J.-M. J. Chem. Soc., Perkin Trans. 1 1995, 879-887. For examples of cyclizations where the directing effect of the nitrogen and the second stabilizing group counteracts, see ref 2b and the following: (l) Beckwith, A. L. J.; Westwood, S. W. Tetrahedron 1989, 45, 5269-5282. (m) Beckwith, A. L. J.; Joseph, S. P.; Mayadunne, R. T. A. J. Org. Chem. 1993, 58, 4198-4199. (n) Cladingboel, D. E.; Parsons, P. J. J. Chem. Soc. Chem. Commun. 1990, 1543-1544. (o) Ishibashi, H.; Kawanami, H.; Iriyama, H.; Ikeda, M. Tetrahedron Lett. 1995, 36, 6733-6734. (p) Ishibashi, H.; Kawanami, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1997, 817-821. (q) Lee, E.; Li, K. S.; Lim, J. Tetrahedron Lett. 1996, 37, 1445-1446. (r) Parker, K. A.; Fokas, D. J. Org. Chem. 1994, 59, 3927-3932. (s) Özlü, Y.; Cladingboel, D. E.; Parsons, P. J. Tetrahedron 1994, 50, 2183-2206. See also: (t) Glover, S. A.; Warkentin, J. J. Org, Chem. 1993, 58, 2115-2121. (u) Okano, T.; Sakaida, T.; Eguchi, S. J. Org. Chem. 1996, 61, 8826-8830.
27. Rigby, J. H.; Mateo, M. E. Tetrahedron 1996, 52, 10569-10582.
28. (a) Schultz, A. G.; Holoboski, M. A.; Smyth, M. S. J. Am. Chem. Soc. 1993, 115, 7904-7905.
29. (b) Schultz, A. G.; Guzzo, P. R.; Nowak, D. M. J. Org. Chem. 1995, 60, 8044-8050.
30. (c) Schultz, A. G.; Holoboski, M. A.; Smyth, M. S. J. Am. Chem. Soc. 1996, 118, 6210-6219.
31. (a) Ripa, L.; Hallberg, A. J. Org. Chem. 1996, 61, 7147-7155.
32. (b) Ripa, L.; Hallberg, A. J. Org. Chem. 1997, 62, 595-602.
33. Triethylborane is known to initiate radical reactions at low temperatures: (a) Nozaki, K.; Oshima, K.; Utimoto, K. J. Am. Chem. Soc. 1987, 109, 2547-2549. (b) Miura, K.; Ichinose, Y.; Nozaki, K.; Fugami, K.; Oshima, K.; Utimoto, K. Bull. Chem. Soc. Jpn. 1989, 62, 143-147. See also: (c) Brown, H. C.; Midland, M. M. Angew. Chem., Int. Ed. Engl. 1972, 11, 692-700.
34. Triethylborane is known to initiate radical reactions at low temperatures: (a) Nozaki, K.; Oshima, K.; Utimoto, K. J. Am. Chem. Soc. 1987, 109, 2547-2549. (b) Miura, K.; Ichinose, Y.; Nozaki, K.; Fugami, K.; Oshima, K.; Utimoto, K. Bull. Chem. Soc. Jpn. 1989, 62, 143-147. See also: (c) Brown, H. C.; Midland, M. M. Angew. Chem., Int. Ed. Engl. 1972, 11, 692-700.
35. Triethylborane is known to initiate radical reactions at low temperatures: (a) Nozaki, K.; Oshima, K.; Utimoto, K. J. Am. Chem. Soc. 1987, 109, 2547-2549. (b) Miura, K.; Ichinose, Y.; Nozaki, K.; Fugami, K.; Oshima, K.; Utimoto, K. Bull. Chem. Soc. Jpn. 1989, 62, 143-147. See also: (c) Brown, H. C.; Midland, M. M. Angew. Chem., Int. Ed. Engl. 1972, 11, 692-700.
36. Even at 85 °C the starting material remained intact. See also ref 6b.
37. Chatgilialoglu, C. Acc. Chem. Res 1992, 25, 188-194.
38. Bowman, R. W.; Heaney, H.; Jordan, B. M. Tetrahedron 1991, 47, 10119-10128. See also refs 2d and 3.
39. 2O) sample of 11a.
40. For examples of disfavored 5-endo cyclization onto enamides by carbamoylmethyl radicals, see: (a) Goodall, K.; Parsons, A. F. J. Chem. Soc., Perkin Trans. 1 1994, 3257-3259.
41. (b) Ishibashi, H.; Nakamura, N.; Sato, T.; Takeuchi, M.; Ikeda, M. Tetrahedron Lett. 1991, 32, 1725-1728.
42. (c) Ishibashi, H.; Fuke, Y.; Yamashita, T.; Ikeda, M. Tetrahedron: Asymmetry 1996, 7, 2531-2538.
43. Sato, T.; Machigashira, N.; Ishibashi, H.; Ikeda, M. Heterocycles 1992, 33, 139-142.
44. (e) Sato, T.; Nakamura, N.; Ikeda, K.; Okada, M.; Ishibashi, H.; Ikeda, M. J. Chem. Soc., Perkin Trans. 1 1992, 2399-2407.
45. (f) Sato, T.; Chono, N.; Ishibashi, H.; Ikeda, M. J. Chem. Soc., Perkin Trans, 1 1995, 1115-1120. See also ref 4b.
46. Spectroscopic data was consistent with data described elsewhere: Meyers, A. I.; Edwards, P. D.; Bailey, T. R.; Jagdmann, G. E. J. J. Org. Chem. 1985, 50, 1019-1026.
47. Ikeda and co-workers have shown that the cyclization does not occur unless a carbonyl group is incorporated in the new ring formed; see refs 11b and 11d.
48. (a) Cannon, J. G.; Hatheway, G. J.; Long, J. P.; Sharabi, F. M. J. Med. Chem. 1976, 19, 987-993.
49. (b) Cannon, J. G.; Suarez-Gutierrez, C.; Lee, T.; Long, J. P.; Costall, B.; Fortune, D. H.; Naylor, R. J. J. Med. Chem. 1979, 22, 341-347.
50. (c) Cannon, J. G. Adv. Biosci. 1979, 20 (Peipher. Dopaminergic Recept.), 87-94.
51. Rubiralta, M.; Giralt, E.; Diez, A. Piperidine. Structure, Preparation, Reactivity, and Synthetic Applications of Piperidine and its Derivatives; Studies in Organic Chemistry 43; Elsevier: Amsterdam, 1991.
52. 3 (2.6 equiv) and benzyl bromide (1.0 equiv) in acetonitrile under argon.
53. (a) Cannon, J. G.; Koble-Suarez, C.; Long, J. P.; Ilhan, M.; Bhatnagar, R. K. J. Pharm. Sci. 1985, 74, 672-675.
54. (b) Cannon, J. G.; Kirschbaum, K. S. Synthesis 1993, 1151-1154.
55. (c) Walsh, D. A.; Smissman, E. E. J. Org. Chem. 1974, 39, 3705-3708.
56. 3 developed by Still was used in the calculations. (b) Mohamadi, F.; Richards, N. G. J.; Guida, W. C.; Liskamp, R.; Lipton, M.; Caufield, C.; Chang, G.; Hendrickson, T.; Still, W. C. J. Comput. Chem. 1990, 11, 440-467. The number of torsion angles allowed to vary simultaneously during each Monte Carlo step ranged from one to four. Conformational searches was conducted by use of the systematic unbound multiple minimum search (SUMM) method in the batchmin program (command SSPMC). (c) Goodman, J. M.; Still, W. C. J. Comput. Chem. 1991, 12, 1110-1117. 5000-step runs were performed, and those conformations within 50 kJ/mol of the global minimum were kept.
57. 3 developed by Still was used in the calculations. (b) Mohamadi, F.; Richards, N. G. J.; Guida, W. C.; Liskamp, R.; Lipton, M.; Caufield, C.; Chang, G.; Hendrickson, T.; Still, W. C. J. Comput. Chem. 1990, 11, 440-467. The number of torsion angles allowed to vary simultaneously during each Monte Carlo step ranged from one to four. Conformational searches was conducted by use of the systematic unbound multiple minimum search (SUMM) method in the batchmin program (command SSPMC). (c) Goodman, J. M.; Still, W. C. J. Comput. Chem. 1991, 12, 1110-1117. 5000-step runs were performed, and those conformations within 50 kJ/mol of the global minimum were kept.
58. 3 developed by Still was used in the calculations. (b) Mohamadi, F.; Richards, N. G. J.; Guida, W. C.; Liskamp, R.; Lipton, M.; Caufield, C.; Chang, G.; Hendrickson, T.; Still, W. C. J. Comput. Chem. 1990, 11, 440-467. The number of torsion angles allowed to vary simultaneously during each Monte Carlo step ranged from one to four. Conformational searches was conducted by use of the systematic unbound multiple minimum search (SUMM) method in the batchmin program (command SSPMC). (c) Goodman, J. M.; Still, W. C. J. Comput. Chem. 1991, 12, 1110-1117. 5000-step runs were performed, and those conformations within 50 kJ/mol of the global minimum were kept.
59. When 2-(2′-bromophenyl)ethyl iodide was used as alkylating agent, the vinyllithium was treated with pentynylcopper prior to alkylation to avoid competing elimination; see ref 5a.
60. The latter process has recently been discussed as a possible mechanism for endo cyclization of aryl radicals onto enamides; see ref 2p.
61. (a) Abeywickrema, A. N.; Beckwith, A. L. J.; Gerba, S. J. Org. Chem. 1987, 52, 4072-4078.
62. (b) Parker, K. A.; Spero, D. M.; Inman, K. C. Tetrahedron Lett. 1986, 27, 2833-2836.
63. The α-nitrogen radical may be sufficiently persistent to relax, prior to hydrogen abstraction, to the configurationally more stable chair-chair structure with the aryl group in equatorial position; see ref 2g for an example.
64. Structural studies of α-aminoalkyl radicals give contradictory results, see: Renaud, P.; Giraud, L. Synthesis 1996, 913-926.
65. (a) Crich, D.; Lim, L. B. L. J. Chem. Soc., Perkin Trans. 1 1991, 2205-2208.
66. (b) Giese, B. Angew. Chem., Int. Ed. Engl. 1989, 28, 969-1146.
67. (c) Korth, H.-G.; Sustmann, R.; Giese, B.; Rückert, B.; Gröninger, K. S. Chem. Ber. 1990, 123, 1891-1898.
68. (d) Renaud, P. Helv. Chim. Acta 1991, 74, 1305-1313.
69. The trans/cis ratio for the reduction of the bridgehead octahydronaphthalene radical is reported to depend on the size of the hydrogen atom donor, giving more cis fused product with bulkier hydrogen donors. Beckwith, A. L. J.; Gream, G. E.; Struble, D. L. Aust. J. Chem. 1972, 25, 1081-1105.
70. Compare with: (a) Ghosh, A. K.; Ghosh, K.; Pal, S.; Ghatak, U. R. J. Chem. Soc. Chem. Commun. 1993, 809-811, 1176. (b) Pal, S.; Mukhopadhyaya, J. K.; Ghatak, U. R. J. Org. Chem. 1994, 59, 2687-2694.
71. Compare with: (a) Ghosh, A. K.; Ghosh, K.; Pal, S.; Ghatak, U. R. J. Chem. Soc. Chem. Commun. 1993, 809-811, 1176. (b) Pal, S.; Mukhopadhyaya, J. K.; Ghatak, U. R. J. Org. Chem. 1994, 59, 2687-2694.
72. Such a 1,5-hydride shift occurs readily to an aryl radical especially when a stabilized radical is formed. (a) Cohen, T.; McMullen, C. H.; Smith, K. J. Am. Chem. Soc. 1968, 90, 6866-6867. (b) Snieckus, V.; Cuevas, J.-C.; Sloan, C. P.; Liu, H.; Curran, D. P. J. Am. Chem. Soc. 1990, 112, 896-898. See also refs 2l and 4b,c.
73. Such a 1,5-hydride shift occurs readily to an aryl radical especially when a stabilized radical is formed. (a) Cohen, T.; McMullen, C. H.; Smith, K. J. Am. Chem. Soc. 1968, 90, 6866-6867. (b) Snieckus, V.; Cuevas, J.-C.; Sloan, C. P.; Liu, H.; Curran, D. P. J. Am. Chem. Soc. 1990, 112, 896-898. See also refs 2l and 4b,c.
74. Tris(trimethylsilyl)silicon hydride is about 13 times slower than triphenyltin hydride at donating a hydrogen atom to an alkyl radical. Newcomb, M. Tetrahedron 1993, 49, 1151-1176.
75. Radicals located α to a nitrogen atom are sensitive to oxidation, see: Curran, D. P. In Comprehensive Organic Synthesis; Trost, B. M.; Fleming, I., Ed.; Pergamon: Oxford, 1991; Vol. 4; p 726.
76. Bogen, S.; Malacria, M. J. Am. Chem. Soc. 1996, 118, 3992-3993.
77. RN1 mechanism has been suggested for similar processes; see ref 9.
78. (a) Beak, P.; Allen, D. J.; Lee, W. K. J. Am. Chem. Soc. 1990, 112, 1629-1630.
79. (b) Wender, P. A.; White, A. W. J. Am. Chem. Soc. 1988, 110, 2218-2223.
80. Beak, P.; Allen, D. J. J. Am. Chem. Soc. 1992, 114, 3420-3425.
81. Ciulfolini, M. A.; Qi, H.-B.; Browne, M. E. J. Org. Chem. 1988, 53, 4149-4151.
82. L'abbé, G.; Leurs, S.; Sannen, I.; Dehaen, W. Tetrahedron 1993, 49, 4439-4446.
83. Bickelhaupt, F.; Stach, K.; Thiel, M. Chem. Ber. 1965, 98, 685-704.
84. Stephens, R. D.; Castro, C. E. J. Org. Chem. 1963, 28, 3313-3315.
85. Gilman, H.; Marrs, O. L. J. Org. Chem. 1965, 30, 325-328.
86. Beeby, M. H.; Mann, F. G. J. Chem. Soc. 1951, 411-415.
87. The amidines were purified essentially according to a procedure developed by Meyers; see ref 12.
88. The reaction times were not optimized.