Remote stereochemical control of both reacting centers in ketyl-olefin radical cyclizations: Involvement of a samarium tridentate ligate

Journal of the American Chemical Society

Volumn 119, Issue 6, 1997, Pages 1265-1276

  Molander, Gary A ^a   McWilliams, J Christopher ^a   Noll, Bruce C ^a  

^a UNIVERSITY OF COLORADO   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

1,3 DIOXOLANE DERIVATIVE; CYCLOPENTANE DERIVATIVE;

ARTICLE; CATALYSIS; CHIRALITY; CYCLIZATION; DRUG SYNTHESIS; IN VITRO STUDY; REACTION ANALYSIS; STEREOCHEMISTRY;

EID: 0030901690     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja963195c     Document Type: Article

References (92)

1. For reviews of diastereoselection in radical reactions, see: (a) Smadja, W. Synlett 1994, 1. (b) Porter, N. A.; Giese, B.; Curran, D. P. Acc. Chem. Res. 1991, 24, 296. See also: (c) Snider, B. B.; Zhang, Q. Tetrahedron Lett 1992, 33, 5921. (d) Toru, T.; Watanabe, Y.; Tsusaka, M.; Ueno, Y. J. Am. Chem. Soc. 1993, 115, 10464. (e) Yamamoto, Y.; Onuki, S.; Yumoto, M.; Asao, N. J. Am. Chem. Soc. 1994, 116, 421. (f) Nishida, M.; Ueyama, E.; Hayashi, H.; Ohtake, Y.; Yamaura, Y.; Yanaginuma, E.; Yonemitsu, O.; Nishida, A.; Kawahara, N. J. Am. Chem. Soc. 1994, 116, 6455. (g) Curran, D. P.; Geib, S. J.; Lin, C.-H. Tetrahedron: Asymmetry 1994, 5, 199. (h) Andrus, M. B.; Argade, A. B.; Chen, X.; Pamment, M. G. Tetrahedron Lett. 1995, 36, 2945. (i) Urabe, H.; Yamashita, K.; Suzuki, K.; Kobayashi, K.; Sato, F. J. Org. Chem. 1995, 60, 3576. (j) Murakata, M.; Tsutsui H.; Hoshino, O. J. Chem. Soc., Chem. Commun. 1995, 481. (k) Renaud, P.; Gerster, M. J. Am. Chem. Soc. 1995, 117, 6607. (l) Sibi, M. P.; Jasperse, C. P.; Ji, J. J. Am. Chem. Soc. 1995, 117, 10779. (m) Wu, J. H.; Radinov, R.; Porter, N. A. J. Am. Chem. Soc. 1995, 117, 11029.
2. For reviews of diastereoselection in radical reactions, see: (a) Smadja, W. Synlett 1994, 1. (b) Porter, N. A.; Giese, B.; Curran, D. P. Acc. Chem. Res. 1991, 24, 296. See also: (c) Snider, B. B.; Zhang, Q. Tetrahedron Lett 1992, 33, 5921. (d) Toru, T.; Watanabe, Y.; Tsusaka, M.; Ueno, Y. J. Am. Chem. Soc. 1993, 115, 10464. (e) Yamamoto, Y.; Onuki, S.; Yumoto, M.; Asao, N. J. Am. Chem. Soc. 1994, 116, 421. (f) Nishida, M.; Ueyama, E.; Hayashi, H.; Ohtake, Y.; Yamaura, Y.; Yanaginuma, E.; Yonemitsu, O.; Nishida, A.; Kawahara, N. J. Am. Chem. Soc. 1994, 116, 6455. (g) Curran, D. P.; Geib, S. J.; Lin, C.-H. Tetrahedron: Asymmetry 1994, 5, 199. (h) Andrus, M. B.; Argade, A. B.; Chen, X.; Pamment, M. G. Tetrahedron Lett. 1995, 36, 2945. (i) Urabe, H.; Yamashita, K.; Suzuki, K.; Kobayashi, K.; Sato, F. J. Org. Chem. 1995, 60, 3576. (j) Murakata, M.; Tsutsui H.; Hoshino, O. J. Chem. Soc., Chem. Commun. 1995, 481. (k) Renaud, P.; Gerster, M. J. Am. Chem. Soc. 1995, 117, 6607. (l) Sibi, M. P.; Jasperse, C. P.; Ji, J. J. Am. Chem. Soc. 1995, 117, 10779. (m) Wu, J. H.; Radinov, R.; Porter, N. A. J. Am. Chem. Soc. 1995, 117, 11029.
3. For reviews of diastereoselection in radical reactions, see: (a) Smadja, W. Synlett 1994, 1. (b) Porter, N. A.; Giese, B.; Curran, D. P. Acc. Chem. Res. 1991, 24, 296. See also: (c) Snider, B. B.; Zhang, Q. Tetrahedron Lett 1992, 33, 5921. (d) Toru, T.; Watanabe, Y.; Tsusaka, M.; Ueno, Y. J. Am. Chem. Soc. 1993, 115, 10464. (e) Yamamoto, Y.; Onuki, S.; Yumoto, M.; Asao, N. J. Am. Chem. Soc. 1994, 116, 421. (f) Nishida, M.; Ueyama, E.; Hayashi, H.; Ohtake, Y.; Yamaura, Y.; Yanaginuma, E.; Yonemitsu, O.; Nishida, A.; Kawahara, N. J. Am. Chem. Soc. 1994, 116, 6455. (g) Curran, D. P.; Geib, S. J.; Lin, C.-H. Tetrahedron: Asymmetry 1994, 5, 199. (h) Andrus, M. B.; Argade, A. B.; Chen, X.; Pamment, M. G. Tetrahedron Lett. 1995, 36, 2945. (i) Urabe, H.; Yamashita, K.; Suzuki, K.; Kobayashi, K.; Sato, F. J. Org. Chem. 1995, 60, 3576. (j) Murakata, M.; Tsutsui H.; Hoshino, O. J. Chem. Soc., Chem. Commun. 1995, 481. (k) Renaud, P.; Gerster, M. J. Am. Chem. Soc. 1995, 117, 6607. (l) Sibi, M. P.; Jasperse, C. P.; Ji, J. J. Am. Chem. Soc. 1995, 117, 10779. (m) Wu, J. H.; Radinov, R.; Porter, N. A. J. Am. Chem. Soc. 1995, 117, 11029.
4. For reviews of diastereoselection in radical reactions, see: (a) Smadja, W. Synlett 1994, 1. (b) Porter, N. A.; Giese, B.; Curran, D. P. Acc. Chem. Res. 1991, 24, 296. See also: (c) Snider, B. B.; Zhang, Q. Tetrahedron Lett 1992, 33, 5921. (d) Toru, T.; Watanabe, Y.; Tsusaka, M.; Ueno, Y. J. Am. Chem. Soc. 1993, 115, 10464. (e) Yamamoto, Y.; Onuki, S.; Yumoto, M.; Asao, N. J. Am. Chem. Soc. 1994, 116, 421. (f) Nishida, M.; Ueyama, E.; Hayashi, H.; Ohtake, Y.; Yamaura, Y.; Yanaginuma, E.; Yonemitsu, O.; Nishida, A.; Kawahara, N. J. Am. Chem. Soc. 1994, 116, 6455. (g) Curran, D. P.; Geib, S. J.; Lin, C.-H. Tetrahedron: Asymmetry 1994, 5, 199. (h) Andrus, M. B.; Argade, A. B.; Chen, X.; Pamment, M. G. Tetrahedron Lett. 1995, 36, 2945. (i) Urabe, H.; Yamashita, K.; Suzuki, K.; Kobayashi, K.; Sato, F. J. Org. Chem. 1995, 60, 3576. (j) Murakata, M.; Tsutsui H.; Hoshino, O. J. Chem. Soc., Chem. Commun. 1995, 481. (k) Renaud, P.; Gerster, M. J. Am. Chem. Soc. 1995, 117, 6607. (l) Sibi, M. P.; Jasperse, C. P.; Ji, J. J. Am. Chem. Soc. 1995, 117, 10779. (m) Wu, J. H.; Radinov, R.; Porter, N. A. J. Am. Chem. Soc. 1995, 117, 11029.
5. For reviews of diastereoselection in radical reactions, see: (a) Smadja, W. Synlett 1994, 1. (b) Porter, N. A.; Giese, B.; Curran, D. P. Acc. Chem. Res. 1991, 24, 296. See also: (c) Snider, B. B.; Zhang, Q. Tetrahedron Lett 1992, 33, 5921. (d) Toru, T.; Watanabe, Y.; Tsusaka, M.; Ueno, Y. J. Am. Chem. Soc. 1993, 115, 10464. (e) Yamamoto, Y.; Onuki, S.; Yumoto, M.; Asao, N. J. Am. Chem. Soc. 1994, 116, 421. (f) Nishida, M.; Ueyama, E.; Hayashi, H.; Ohtake, Y.; Yamaura, Y.; Yanaginuma, E.; Yonemitsu, O.; Nishida, A.; Kawahara, N. J. Am. Chem. Soc. 1994, 116, 6455. (g) Curran, D. P.; Geib, S. J.; Lin, C.-H. Tetrahedron: Asymmetry 1994, 5, 199. (h) Andrus, M. B.; Argade, A. B.; Chen, X.; Pamment, M. G. Tetrahedron Lett. 1995, 36, 2945. (i) Urabe, H.; Yamashita, K.; Suzuki, K.; Kobayashi, K.; Sato, F. J. Org. Chem. 1995, 60, 3576. (j) Murakata, M.; Tsutsui H.; Hoshino, O. J. Chem. Soc., Chem. Commun. 1995, 481. (k) Renaud, P.; Gerster, M. J. Am. Chem. Soc. 1995, 117, 6607. (l) Sibi, M. P.; Jasperse, C. P.; Ji, J. J. Am. Chem. Soc. 1995, 117, 10779. (m) Wu, J. H.; Radinov, R.; Porter, N. A. J. Am. Chem. Soc. 1995, 117, 11029.
6. For reviews of diastereoselection in radical reactions, see: (a) Smadja, W. Synlett 1994, 1. (b) Porter, N. A.; Giese, B.; Curran, D. P. Acc. Chem. Res. 1991, 24, 296. See also: (c) Snider, B. B.; Zhang, Q. Tetrahedron Lett 1992, 33, 5921. (d) Toru, T.; Watanabe, Y.; Tsusaka, M.; Ueno, Y. J. Am. Chem. Soc. 1993, 115, 10464. (e) Yamamoto, Y.; Onuki, S.; Yumoto, M.; Asao, N. J. Am. Chem. Soc. 1994, 116, 421. (f) Nishida, M.; Ueyama, E.; Hayashi, H.; Ohtake, Y.; Yamaura, Y.; Yanaginuma, E.; Yonemitsu, O.; Nishida, A.; Kawahara, N. J. Am. Chem. Soc. 1994, 116, 6455. (g) Curran, D. P.; Geib, S. J.; Lin, C.-H. Tetrahedron: Asymmetry 1994, 5, 199. (h) Andrus, M. B.; Argade, A. B.; Chen, X.; Pamment, M. G. Tetrahedron Lett. 1995, 36, 2945. (i) Urabe, H.; Yamashita, K.; Suzuki, K.; Kobayashi, K.; Sato, F. J. Org. Chem. 1995, 60, 3576. (j) Murakata, M.; Tsutsui H.; Hoshino, O. J. Chem. Soc., Chem. Commun. 1995, 481. (k) Renaud, P.; Gerster, M. J. Am. Chem. Soc. 1995, 117, 6607. (l) Sibi, M. P.; Jasperse, C. P.; Ji, J. J. Am. Chem. Soc. 1995, 117, 10779. (m) Wu, J. H.; Radinov, R.; Porter, N. A. J. Am. Chem. Soc. 1995, 117, 11029.
7. For reviews of diastereoselection in radical reactions, see: (a) Smadja, W. Synlett 1994, 1. (b) Porter, N. A.; Giese, B.; Curran, D. P. Acc. Chem. Res. 1991, 24, 296. See also: (c) Snider, B. B.; Zhang, Q. Tetrahedron Lett 1992, 33, 5921. (d) Toru, T.; Watanabe, Y.; Tsusaka, M.; Ueno, Y. J. Am. Chem. Soc. 1993, 115, 10464. (e) Yamamoto, Y.; Onuki, S.; Yumoto, M.; Asao, N. J. Am. Chem. Soc. 1994, 116, 421. (f) Nishida, M.; Ueyama, E.; Hayashi, H.; Ohtake, Y.; Yamaura, Y.; Yanaginuma, E.; Yonemitsu, O.; Nishida, A.; Kawahara, N. J. Am. Chem. Soc. 1994, 116, 6455. (g) Curran, D. P.; Geib, S. J.; Lin, C.-H. Tetrahedron: Asymmetry 1994, 5, 199. (h) Andrus, M. B.; Argade, A. B.; Chen, X.; Pamment, M. G. Tetrahedron Lett. 1995, 36, 2945. (i) Urabe, H.; Yamashita, K.; Suzuki, K.; Kobayashi, K.; Sato, F. J. Org. Chem. 1995, 60, 3576. (j) Murakata, M.; Tsutsui H.; Hoshino, O. J. Chem. Soc., Chem. Commun. 1995, 481. (k) Renaud, P.; Gerster, M. J. Am. Chem. Soc. 1995, 117, 6607. (l) Sibi, M. P.; Jasperse, C. P.; Ji, J. J. Am. Chem. Soc. 1995, 117, 10779. (m) Wu, J. H.; Radinov, R.; Porter, N. A. J. Am. Chem. Soc. 1995, 117, 11029.
8. For reviews of diastereoselection in radical reactions, see: (a) Smadja, W. Synlett 1994, 1. (b) Porter, N. A.; Giese, B.; Curran, D. P. Acc. Chem. Res. 1991, 24, 296. See also: (c) Snider, B. B.; Zhang, Q. Tetrahedron Lett 1992, 33, 5921. (d) Toru, T.; Watanabe, Y.; Tsusaka, M.; Ueno, Y. J. Am. Chem. Soc. 1993, 115, 10464. (e) Yamamoto, Y.; Onuki, S.; Yumoto, M.; Asao, N. J. Am. Chem. Soc. 1994, 116, 421. (f) Nishida, M.; Ueyama, E.; Hayashi, H.; Ohtake, Y.; Yamaura, Y.; Yanaginuma, E.; Yonemitsu, O.; Nishida, A.; Kawahara, N. J. Am. Chem. Soc. 1994, 116, 6455. (g) Curran, D. P.; Geib, S. J.; Lin, C.-H. Tetrahedron: Asymmetry 1994, 5, 199. (h) Andrus, M. B.; Argade, A. B.; Chen, X.; Pamment, M. G. Tetrahedron Lett. 1995, 36, 2945. (i) Urabe, H.; Yamashita, K.; Suzuki, K.; Kobayashi, K.; Sato, F. J. Org. Chem. 1995, 60, 3576. (j) Murakata, M.; Tsutsui H.; Hoshino, O. J. Chem. Soc., Chem. Commun. 1995, 481. (k) Renaud, P.; Gerster, M. J. Am. Chem. Soc. 1995, 117, 6607. (l) Sibi, M. P.; Jasperse, C. P.; Ji, J. J. Am. Chem. Soc. 1995, 117, 10779. (m) Wu, J. H.; Radinov, R.; Porter, N. A. J. Am. Chem. Soc. 1995, 117, 11029.
9. For reviews of diastereoselection in radical reactions, see: (a) Smadja, W. Synlett 1994, 1. (b) Porter, N. A.; Giese, B.; Curran, D. P. Acc. Chem. Res. 1991, 24, 296. See also: (c) Snider, B. B.; Zhang, Q. Tetrahedron Lett 1992, 33, 5921. (d) Toru, T.; Watanabe, Y.; Tsusaka, M.; Ueno, Y. J. Am. Chem. Soc. 1993, 115, 10464. (e) Yamamoto, Y.; Onuki, S.; Yumoto, M.; Asao, N. J. Am. Chem. Soc. 1994, 116, 421. (f) Nishida, M.; Ueyama, E.; Hayashi, H.; Ohtake, Y.; Yamaura, Y.; Yanaginuma, E.; Yonemitsu, O.; Nishida, A.; Kawahara, N. J. Am. Chem. Soc. 1994, 116, 6455. (g) Curran, D. P.; Geib, S. J.; Lin, C.-H. Tetrahedron: Asymmetry 1994, 5, 199. (h) Andrus, M. B.; Argade, A. B.; Chen, X.; Pamment, M. G. Tetrahedron Lett. 1995, 36, 2945. (i) Urabe, H.; Yamashita, K.; Suzuki, K.; Kobayashi, K.; Sato, F. J. Org. Chem. 1995, 60, 3576. (j) Murakata, M.; Tsutsui H.; Hoshino, O. J. Chem. Soc., Chem. Commun. 1995, 481. (k) Renaud, P.; Gerster, M. J. Am. Chem. Soc. 1995, 117, 6607. (l) Sibi, M. P.; Jasperse, C. P.; Ji, J. J. Am. Chem. Soc. 1995, 117, 10779. (m) Wu, J. H.; Radinov, R.; Porter, N. A. J. Am. Chem. Soc. 1995, 117, 11029.
10. For reviews of diastereoselection in radical reactions, see: (a) Smadja, W. Synlett 1994, 1. (b) Porter, N. A.; Giese, B.; Curran, D. P. Acc. Chem. Res. 1991, 24, 296. See also: (c) Snider, B. B.; Zhang, Q. Tetrahedron Lett 1992, 33, 5921. (d) Toru, T.; Watanabe, Y.; Tsusaka, M.; Ueno, Y. J. Am. Chem. Soc. 1993, 115, 10464. (e) Yamamoto, Y.; Onuki, S.; Yumoto, M.; Asao, N. J. Am. Chem. Soc. 1994, 116, 421. (f) Nishida, M.; Ueyama, E.; Hayashi, H.; Ohtake, Y.; Yamaura, Y.; Yanaginuma, E.; Yonemitsu, O.; Nishida, A.; Kawahara, N. J. Am. Chem. Soc. 1994, 116, 6455. (g) Curran, D. P.; Geib, S. J.; Lin, C.-H. Tetrahedron: Asymmetry 1994, 5, 199. (h) Andrus, M. B.; Argade, A. B.; Chen, X.; Pamment, M. G. Tetrahedron Lett. 1995, 36, 2945. (i) Urabe, H.; Yamashita, K.; Suzuki, K.; Kobayashi, K.; Sato, F. J. Org. Chem. 1995, 60, 3576. (j) Murakata, M.; Tsutsui H.; Hoshino, O. J. Chem. Soc., Chem. Commun. 1995, 481. (k) Renaud, P.; Gerster, M. J. Am. Chem. Soc. 1995, 117, 6607. (l) Sibi, M. P.; Jasperse, C. P.; Ji, J. J. Am. Chem. Soc. 1995, 117, 10779. (m) Wu, J. H.; Radinov, R.; Porter, N. A. J. Am. Chem. Soc. 1995, 117, 11029.
11. For reviews of diastereoselection in radical reactions, see: (a) Smadja, W. Synlett 1994, 1. (b) Porter, N. A.; Giese, B.; Curran, D. P. Acc. Chem. Res. 1991, 24, 296. See also: (c) Snider, B. B.; Zhang, Q. Tetrahedron Lett 1992, 33, 5921. (d) Toru, T.; Watanabe, Y.; Tsusaka, M.; Ueno, Y. J. Am. Chem. Soc. 1993, 115, 10464. (e) Yamamoto, Y.; Onuki, S.; Yumoto, M.; Asao, N. J. Am. Chem. Soc. 1994, 116, 421. (f) Nishida, M.; Ueyama, E.; Hayashi, H.; Ohtake, Y.; Yamaura, Y.; Yanaginuma, E.; Yonemitsu, O.; Nishida, A.; Kawahara, N. J. Am. Chem. Soc. 1994, 116, 6455. (g) Curran, D. P.; Geib, S. J.; Lin, C.-H. Tetrahedron: Asymmetry 1994, 5, 199. (h) Andrus, M. B.; Argade, A. B.; Chen, X.; Pamment, M. G. Tetrahedron Lett. 1995, 36, 2945. (i) Urabe, H.; Yamashita, K.; Suzuki, K.; Kobayashi, K.; Sato, F. J. Org. Chem. 1995, 60, 3576. (j) Murakata, M.; Tsutsui H.; Hoshino, O. J. Chem. Soc., Chem. Commun. 1995, 481. (k) Renaud, P.; Gerster, M. J. Am. Chem. Soc. 1995, 117, 6607. (l) Sibi, M. P.; Jasperse, C. P.; Ji, J. J. Am. Chem. Soc. 1995, 117, 10779. (m) Wu, J. H.; Radinov, R.; Porter, N. A. J. Am. Chem. Soc. 1995, 117, 11029.
12. For reviews of diastereoselection in radical reactions, see: (a) Smadja, W. Synlett 1994, 1. (b) Porter, N. A.; Giese, B.; Curran, D. P. Acc. Chem. Res. 1991, 24, 296. See also: (c) Snider, B. B.; Zhang, Q. Tetrahedron Lett 1992, 33, 5921. (d) Toru, T.; Watanabe, Y.; Tsusaka, M.; Ueno, Y. J. Am. Chem. Soc. 1993, 115, 10464. (e) Yamamoto, Y.; Onuki, S.; Yumoto, M.; Asao, N. J. Am. Chem. Soc. 1994, 116, 421. (f) Nishida, M.; Ueyama, E.; Hayashi, H.; Ohtake, Y.; Yamaura, Y.; Yanaginuma, E.; Yonemitsu, O.; Nishida, A.; Kawahara, N. J. Am. Chem. Soc. 1994, 116, 6455. (g) Curran, D. P.; Geib, S. J.; Lin, C.-H. Tetrahedron: Asymmetry 1994, 5, 199. (h) Andrus, M. B.; Argade, A. B.; Chen, X.; Pamment, M. G. Tetrahedron Lett. 1995, 36, 2945. (i) Urabe, H.; Yamashita, K.; Suzuki, K.; Kobayashi, K.; Sato, F. J. Org. Chem. 1995, 60, 3576. (j) Murakata, M.; Tsutsui H.; Hoshino, O. J. Chem. Soc., Chem. Commun. 1995, 481. (k) Renaud, P.; Gerster, M. J. Am. Chem. Soc. 1995, 117, 6607. (l) Sibi, M. P.; Jasperse, C. P.; Ji, J. J. Am. Chem. Soc. 1995, 117, 10779. (m) Wu, J. H.; Radinov, R.; Porter, N. A. J. Am. Chem. Soc. 1995, 117, 11029.
13. For reviews of diastereoselection in radical reactions, see: (a) Smadja, W. Synlett 1994, 1. (b) Porter, N. A.; Giese, B.; Curran, D. P. Acc. Chem. Res. 1991, 24, 296. See also: (c) Snider, B. B.; Zhang, Q. Tetrahedron Lett 1992, 33, 5921. (d) Toru, T.; Watanabe, Y.; Tsusaka, M.; Ueno, Y. J. Am. Chem. Soc. 1993, 115, 10464. (e) Yamamoto, Y.; Onuki, S.; Yumoto, M.; Asao, N. J. Am. Chem. Soc. 1994, 116, 421. (f) Nishida, M.; Ueyama, E.; Hayashi, H.; Ohtake, Y.; Yamaura, Y.; Yanaginuma, E.; Yonemitsu, O.; Nishida, A.; Kawahara, N. J. Am. Chem. Soc. 1994, 116, 6455. (g) Curran, D. P.; Geib, S. J.; Lin, C.-H. Tetrahedron: Asymmetry 1994, 5, 199. (h) Andrus, M. B.; Argade, A. B.; Chen, X.; Pamment, M. G. Tetrahedron Lett. 1995, 36, 2945. (i) Urabe, H.; Yamashita, K.; Suzuki, K.; Kobayashi, K.; Sato, F. J. Org. Chem. 1995, 60, 3576. (j) Murakata, M.; Tsutsui H.; Hoshino, O. J. Chem. Soc., Chem. Commun. 1995, 481. (k) Renaud, P.; Gerster, M. J. Am. Chem. Soc. 1995, 117, 6607. (l) Sibi, M. P.; Jasperse, C. P.; Ji, J. J. Am. Chem. Soc. 1995, 117, 10779. (m) Wu, J. H.; Radinov, R.; Porter, N. A. J. Am. Chem. Soc. 1995, 117, 11029.
14. For recent examples, see: (a) Molander, G. A.; Haar, Jr., J. P. J. Am. Chem. Soc. 1993, 115, 40. (b) Molander, G. A.; Bobbitt, K. L. J. Am. Chem. Soc. 1993, 115, 7517. (c) Teerawutgulrag, A.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1993, 2863. (d) Carey, J. S.; Coulter, T. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3933. (e) Carey, J. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3935. (d) Molander, G. A.; Bobbitt, K. L. J. Org. Chem. 1994, 59, 2676. (e) Carey, J. S.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 283. (f) Stanway, S. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 285. (g) Ahzng, H.-C.; Costanzo, M. J.; Maryanoff, B. E. Tetrahedron Lett. 1994, 35, 4891. (h) Hallen, D. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1995, 657. (i) Gruttadauria, M.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1995, 1469. (j) Stanway, S. J.; Thomas, E. J. Synlett 1995, 214. (k) Stanway, S. J.; Thomas, E. J. Tetrahedron Lett. 1995, 36, 3417.
15. For recent examples, see: (a) Molander, G. A.; Haar, Jr., J. P. J. Am. Chem. Soc. 1993, 115, 40. (b) Molander, G. A.; Bobbitt, K. L. J. Am. Chem. Soc. 1993, 115, 7517. (c) Teerawutgulrag, A.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1993, 2863. (d) Carey, J. S.; Coulter, T. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3933. (e) Carey, J. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3935. (d) Molander, G. A.; Bobbitt, K. L. J. Org. Chem. 1994, 59, 2676. (e) Carey, J. S.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 283. (f) Stanway, S. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 285. (g) Ahzng, H.-C.; Costanzo, M. J.; Maryanoff, B. E. Tetrahedron Lett. 1994, 35, 4891. (h) Hallen, D. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1995, 657. (i) Gruttadauria, M.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1995, 1469. (j) Stanway, S. J.; Thomas, E. J. Synlett 1995, 214. (k) Stanway, S. J.; Thomas, E. J. Tetrahedron Lett. 1995, 36, 3417.
16. For recent examples, see: (a) Molander, G. A.; Haar, Jr., J. P. J. Am. Chem. Soc. 1993, 115, 40. (b) Molander, G. A.; Bobbitt, K. L. J. Am. Chem. Soc. 1993, 115, 7517. (c) Teerawutgulrag, A.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1993, 2863. (d) Carey, J. S.; Coulter, T. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3933. (e) Carey, J. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3935. (d) Molander, G. A.; Bobbitt, K. L. J. Org. Chem. 1994, 59, 2676. (e) Carey, J. S.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 283. (f) Stanway, S. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 285. (g) Ahzng, H.-C.; Costanzo, M. J.; Maryanoff, B. E. Tetrahedron Lett. 1994, 35, 4891. (h) Hallen, D. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1995, 657. (i) Gruttadauria, M.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1995, 1469. (j) Stanway, S. J.; Thomas, E. J. Synlett 1995, 214. (k) Stanway, S. J.; Thomas, E. J. Tetrahedron Lett. 1995, 36, 3417.
17. For recent examples, see: (a) Molander, G. A.; Haar, Jr., J. P. J. Am. Chem. Soc. 1993, 115, 40. (b) Molander, G. A.; Bobbitt, K. L. J. Am. Chem. Soc. 1993, 115, 7517. (c) Teerawutgulrag, A.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1993, 2863. (d) Carey, J. S.; Coulter, T. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3933. (e) Carey, J. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3935. (d) Molander, G. A.; Bobbitt, K. L. J. Org. Chem. 1994, 59, 2676. (e) Carey, J. S.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 283. (f) Stanway, S. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 285. (g) Ahzng, H.-C.; Costanzo, M. J.; Maryanoff, B. E. Tetrahedron Lett. 1994, 35, 4891. (h) Hallen, D. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1995, 657. (i) Gruttadauria, M.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1995, 1469. (j) Stanway, S. J.; Thomas, E. J. Synlett 1995, 214. (k) Stanway, S. J.; Thomas, E. J. Tetrahedron Lett. 1995, 36, 3417.
18. For recent examples, see: (a) Molander, G. A.; Haar, Jr., J. P. J. Am. Chem. Soc. 1993, 115, 40. (b) Molander, G. A.; Bobbitt, K. L. J. Am. Chem. Soc. 1993, 115, 7517. (c) Teerawutgulrag, A.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1993, 2863. (d) Carey, J. S.; Coulter, T. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3933. (e) Carey, J. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3935. (d) Molander, G. A.; Bobbitt, K. L. J. Org. Chem. 1994, 59, 2676. (e) Carey, J. S.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 283. (f) Stanway, S. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 285. (g) Ahzng, H.-C.; Costanzo, M. J.; Maryanoff, B. E. Tetrahedron Lett. 1994, 35, 4891. (h) Hallen, D. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1995, 657. (i) Gruttadauria, M.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1995, 1469. (j) Stanway, S. J.; Thomas, E. J. Synlett 1995, 214. (k) Stanway, S. J.; Thomas, E. J. Tetrahedron Lett. 1995, 36, 3417.
19. For recent examples, see: (a) Molander, G. A.; Haar, Jr., J. P. J. Am. Chem. Soc. 1993, 115, 40. (b) Molander, G. A.; Bobbitt, K. L. J. Am. Chem. Soc. 1993, 115, 7517. (c) Teerawutgulrag, A.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1993, 2863. (d) Carey, J. S.; Coulter, T. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3933. (e) Carey, J. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3935. (d) Molander, G. A.; Bobbitt, K. L. J. Org. Chem. 1994, 59, 2676. (e) Carey, J. S.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 283. (f) Stanway, S. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 285. (g) Ahzng, H.-C.; Costanzo, M. J.; Maryanoff, B. E. Tetrahedron Lett. 1994, 35, 4891. (h) Hallen, D. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1995, 657. (i) Gruttadauria, M.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1995, 1469. (j) Stanway, S. J.; Thomas, E. J. Synlett 1995, 214. (k) Stanway, S. J.; Thomas, E. J. Tetrahedron Lett. 1995, 36, 3417.
20. For recent examples, see: (a) Molander, G. A.; Haar, Jr., J. P. J. Am. Chem. Soc. 1993, 115, 40. (b) Molander, G. A.; Bobbitt, K. L. J. Am. Chem. Soc. 1993, 115, 7517. (c) Teerawutgulrag, A.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1993, 2863. (d) Carey, J. S.; Coulter, T. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3933. (e) Carey, J. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3935. (d) Molander, G. A.; Bobbitt, K. L. J. Org. Chem. 1994, 59, 2676. (e) Carey, J. S.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 283. (f) Stanway, S. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 285. (g) Ahzng, H.-C.; Costanzo, M. J.; Maryanoff, B. E. Tetrahedron Lett. 1994, 35, 4891. (h) Hallen, D. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1995, 657. (i) Gruttadauria, M.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1995, 1469. (j) Stanway, S. J.; Thomas, E. J. Synlett 1995, 214. (k) Stanway, S. J.; Thomas, E. J. Tetrahedron Lett. 1995, 36, 3417.
21. For recent examples, see: (a) Molander, G. A.; Haar, Jr., J. P. J. Am. Chem. Soc. 1993, 115, 40. (b) Molander, G. A.; Bobbitt, K. L. J. Am. Chem. Soc. 1993, 115, 7517. (c) Teerawutgulrag, A.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1993, 2863. (d) Carey, J. S.; Coulter, T. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3933. (e) Carey, J. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3935. (d) Molander, G. A.; Bobbitt, K. L. J. Org. Chem. 1994, 59, 2676. (e) Carey, J. S.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 283. (f) Stanway, S. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 285. (g) Ahzng, H.-C.; Costanzo, M. J.; Maryanoff, B. E. Tetrahedron Lett. 1994, 35, 4891. (h) Hallen, D. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1995, 657. (i) Gruttadauria, M.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1995, 1469. (j) Stanway, S. J.; Thomas, E. J. Synlett 1995, 214. (k) Stanway, S. J.; Thomas, E. J. Tetrahedron Lett. 1995, 36, 3417.
22. For recent examples, see: (a) Molander, G. A.; Haar, Jr., J. P. J. Am. Chem. Soc. 1993, 115, 40. (b) Molander, G. A.; Bobbitt, K. L. J. Am. Chem. Soc. 1993, 115, 7517. (c) Teerawutgulrag, A.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1993, 2863. (d) Carey, J. S.; Coulter, T. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3933. (e) Carey, J. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3935. (d) Molander, G. A.; Bobbitt, K. L. J. Org. Chem. 1994, 59, 2676. (e) Carey, J. S.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 283. (f) Stanway, S. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 285. (g) Ahzng, H.-C.; Costanzo, M. J.; Maryanoff, B. E. Tetrahedron Lett. 1994, 35, 4891. (h) Hallen, D. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1995, 657. (i) Gruttadauria, M.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1995, 1469. (j) Stanway, S. J.; Thomas, E. J. Synlett 1995, 214. (k) Stanway, S. J.; Thomas, E. J. Tetrahedron Lett. 1995, 36, 3417.
23. For recent examples, see: (a) Molander, G. A.; Haar, Jr., J. P. J. Am. Chem. Soc. 1993, 115, 40. (b) Molander, G. A.; Bobbitt, K. L. J. Am. Chem. Soc. 1993, 115, 7517. (c) Teerawutgulrag, A.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1993, 2863. (d) Carey, J. S.; Coulter, T. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3933. (e) Carey, J. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3935. (d) Molander, G. A.; Bobbitt, K. L. J. Org. Chem. 1994, 59, 2676. (e) Carey, J. S.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 283. (f) Stanway, S. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 285. (g) Ahzng, H.-C.; Costanzo, M. J.; Maryanoff, B. E. Tetrahedron Lett. 1994, 35, 4891. (h) Hallen, D. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1995, 657. (i) Gruttadauria, M.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1995, 1469. (j) Stanway, S. J.; Thomas, E. J. Synlett 1995, 214. (k) Stanway, S. J.; Thomas, E. J. Tetrahedron Lett. 1995, 36, 3417.
24. For recent examples, see: (a) Molander, G. A.; Haar, Jr., J. P. J. Am. Chem. Soc. 1993, 115, 40. (b) Molander, G. A.; Bobbitt, K. L. J. Am. Chem. Soc. 1993, 115, 7517. (c) Teerawutgulrag, A.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1993, 2863. (d) Carey, J. S.; Coulter, T. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3933. (e) Carey, J. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3935. (d) Molander, G. A.; Bobbitt, K. L. J. Org. Chem. 1994, 59, 2676. (e) Carey, J. S.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 283. (f) Stanway, S. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 285. (g) Ahzng, H.-C.; Costanzo, M. J.; Maryanoff, B. E. Tetrahedron Lett. 1994, 35, 4891. (h) Hallen, D. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1995, 657. (i) Gruttadauria, M.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1995, 1469. (j) Stanway, S. J.; Thomas, E. J. Synlett 1995, 214. (k) Stanway, S. J.; Thomas, E. J. Tetrahedron Lett. 1995, 36, 3417.
25. For recent examples, see: (a) Molander, G. A.; Haar, Jr., J. P. J. Am. Chem. Soc. 1993, 115, 40. (b) Molander, G. A.; Bobbitt, K. L. J. Am. Chem. Soc. 1993, 115, 7517. (c) Teerawutgulrag, A.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1993, 2863. (d) Carey, J. S.; Coulter, T. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3933. (e) Carey, J. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3935. (d) Molander, G. A.; Bobbitt, K. L. J. Org. Chem. 1994, 59, 2676. (e) Carey, J. S.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 283. (f) Stanway, S. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 285. (g) Ahzng, H.-C.; Costanzo, M. J.; Maryanoff, B. E. Tetrahedron Lett. 1994, 35, 4891. (h) Hallen, D. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1995, 657. (i) Gruttadauria, M.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1995, 1469. (j) Stanway, S. J.; Thomas, E. J. Synlett 1995, 214. (k) Stanway, S. J.; Thomas, E. J. Tetrahedron Lett. 1995, 36, 3417.
26. For recent examples, see: (a) Molander, G. A.; Haar, Jr., J. P. J. Am. Chem. Soc. 1993, 115, 40. (b) Molander, G. A.; Bobbitt, K. L. J. Am. Chem. Soc. 1993, 115, 7517. (c) Teerawutgulrag, A.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1993, 2863. (d) Carey, J. S.; Coulter, T. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3933. (e) Carey, J. S.; Thomas, E. J. Tetrahedron Lett. 1993, 34, 3935. (d) Molander, G. A.; Bobbitt, K. L. J. Org. Chem. 1994, 59, 2676. (e) Carey, J. S.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 283. (f) Stanway, S. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1994, 285. (g) Ahzng, H.-C.; Costanzo, M. J.; Maryanoff, B. E. Tetrahedron Lett. 1994, 35, 4891. (h) Hallen, D. J.; Thomas, E. J. J. Chem. Soc., Chem. Commun. 1995, 657. (i) Gruttadauria, M.; Thomas, E. J. J. Chem. Soc., Perkin Trans. 1 1995, 1469. (j) Stanway, S. J.; Thomas, E. J. Synlett 1995, 214. (k) Stanway, S. J.; Thomas, E. J. Tetrahedron Lett. 1995, 36, 3417.
27. For recent examples of the application of Lewis acids to stereoselective radical transformations, see: (a) Renaud, P.; Ribezzo, M. J. Am. Chem. Soc. 1991, 113, 7803. (b) Guindon, Y.; Lavellée, J.-F.; Llinas-Brunet, M.; Homer, G.; Rancourt, J. J. Am. Chem. Soc. 1991, 113, 9701. (c) Feldman, K. S.; Romanelli, A. L.; Ruckle, Jr., R. E. J. Org. Chem. 1992, 57, 100. (d) Renaud, P.; Moufid, N.; Kuo, L. H.; Curran, D. P. J. Org. Chem. 1994, 59, 3547. (e) Renaud, P.; Bourquard, T.; Gerster, M.; Moufid, N. Angew. Chem., Int. Ed. Engl. 1994, 33, 1601. (f) Guindon, Y.; Guérin, B.; Chabot, C.; Mackintosh, N.; Ogilvie, W. W. Synlett 1995, 449. (g) Sibi, M. P.; Ji, J.; Hongliu, W.; Gürtler, S.; Porter, N. A. J. Am. Chem. Soc. 1996, 118, 9200 and references therein.
28. For recent examples of the application of Lewis acids to stereoselective radical transformations, see: (a) Renaud, P.; Ribezzo, M. J. Am. Chem. Soc. 1991, 113, 7803. (b) Guindon, Y.; Lavellée, J.-F.; Llinas-Brunet, M.; Homer, G.; Rancourt, J. J. Am. Chem. Soc. 1991, 113, 9701. (c) Feldman, K. S.; Romanelli, A. L.; Ruckle, Jr., R. E. J. Org. Chem. 1992, 57, 100. (d) Renaud, P.; Moufid, N.; Kuo, L. H.; Curran, D. P. J. Org. Chem. 1994, 59, 3547. (e) Renaud, P.; Bourquard, T.; Gerster, M.; Moufid, N. Angew. Chem., Int. Ed. Engl. 1994, 33, 1601. (f) Guindon, Y.; Guérin, B.; Chabot, C.; Mackintosh, N.; Ogilvie, W. W. Synlett 1995, 449. (g) Sibi, M. P.; Ji, J.; Hongliu, W.; Gürtler, S.; Porter, N. A. J. Am. Chem. Soc. 1996, 118, 9200 and references therein.
29. For recent examples of the application of Lewis acids to stereoselective radical transformations, see: (a) Renaud, P.; Ribezzo, M. J. Am. Chem. Soc. 1991, 113, 7803. (b) Guindon, Y.; Lavellée, J.-F.; Llinas-Brunet, M.; Homer, G.; Rancourt, J. J. Am. Chem. Soc. 1991, 113, 9701. (c) Feldman, K. S.; Romanelli, A. L.; Ruckle, Jr., R. E. J. Org. Chem. 1992, 57, 100. (d) Renaud, P.; Moufid, N.; Kuo, L. H.; Curran, D. P. J. Org. Chem. 1994, 59, 3547. (e) Renaud, P.; Bourquard, T.; Gerster, M.; Moufid, N. Angew. Chem., Int. Ed. Engl. 1994, 33, 1601. (f) Guindon, Y.; Guérin, B.; Chabot, C.; Mackintosh, N.; Ogilvie, W. W. Synlett 1995, 449. (g) Sibi, M. P.; Ji, J.; Hongliu, W.; Gürtler, S.; Porter, N. A. J. Am. Chem. Soc. 1996, 118, 9200 and references therein.
30. For recent examples of the application of Lewis acids to stereoselective radical transformations, see: (a) Renaud, P.; Ribezzo, M. J. Am. Chem. Soc. 1991, 113, 7803. (b) Guindon, Y.; Lavellée, J.-F.; Llinas-Brunet, M.; Homer, G.; Rancourt, J. J. Am. Chem. Soc. 1991, 113, 9701. (c) Feldman, K. S.; Romanelli, A. L.; Ruckle, Jr., R. E. J. Org. Chem. 1992, 57, 100. (d) Renaud, P.; Moufid, N.; Kuo, L. H.; Curran, D. P. J. Org. Chem. 1994, 59, 3547. (e) Renaud, P.; Bourquard, T.; Gerster, M.; Moufid, N. Angew. Chem., Int. Ed. Engl. 1994, 33, 1601. (f) Guindon, Y.; Guérin, B.; Chabot, C.; Mackintosh, N.; Ogilvie, W. W. Synlett 1995, 449. (g) Sibi, M. P.; Ji, J.; Hongliu, W.; Gürtler, S.; Porter, N. A. J. Am. Chem. Soc. 1996, 118, 9200 and references therein.
31. For recent examples of the application of Lewis acids to stereoselective radical transformations, see: (a) Renaud, P.; Ribezzo, M. J. Am. Chem. Soc. 1991, 113, 7803. (b) Guindon, Y.; Lavellée, J.-F.; Llinas-Brunet, M.; Homer, G.; Rancourt, J. J. Am. Chem. Soc. 1991, 113, 9701. (c) Feldman, K. S.; Romanelli, A. L.; Ruckle, Jr., R. E. J. Org. Chem. 1992, 57, 100. (d) Renaud, P.; Moufid, N.; Kuo, L. H.; Curran, D. P. J. Org. Chem. 1994, 59, 3547. (e) Renaud, P.; Bourquard, T.; Gerster, M.; Moufid, N. Angew. Chem., Int. Ed. Engl. 1994, 33, 1601. (f) Guindon, Y.; Guérin, B.; Chabot, C.; Mackintosh, N.; Ogilvie, W. W. Synlett 1995, 449. (g) Sibi, M. P.; Ji, J.; Hongliu, W.; Gürtler, S.; Porter, N. A. J. Am. Chem. Soc. 1996, 118, 9200 and references therein.
32. For recent examples of the application of Lewis acids to stereoselective radical transformations, see: (a) Renaud, P.; Ribezzo, M. J. Am. Chem. Soc. 1991, 113, 7803. (b) Guindon, Y.; Lavellée, J.-F.; Llinas-Brunet, M.; Homer, G.; Rancourt, J. J. Am. Chem. Soc. 1991, 113, 9701. (c) Feldman, K. S.; Romanelli, A. L.; Ruckle, Jr., R. E. J. Org. Chem. 1992, 57, 100. (d) Renaud, P.; Moufid, N.; Kuo, L. H.; Curran, D. P. J. Org. Chem. 1994, 59, 3547. (e) Renaud, P.; Bourquard, T.; Gerster, M.; Moufid, N. Angew. Chem., Int. Ed. Engl. 1994, 33, 1601. (f) Guindon, Y.; Guérin, B.; Chabot, C.; Mackintosh, N.; Ogilvie, W. W. Synlett 1995, 449. (g) Sibi, M. P.; Ji, J.; Hongliu, W.; Gürtler, S.; Porter, N. A. J. Am. Chem. Soc. 1996, 118, 9200 and references therein.
33. For recent examples of the application of Lewis acids to stereoselective radical transformations, see: (a) Renaud, P.; Ribezzo, M. J. Am. Chem. Soc. 1991, 113, 7803. (b) Guindon, Y.; Lavellée, J.-F.; Llinas-Brunet, M.; Homer, G.; Rancourt, J. J. Am. Chem. Soc. 1991, 113, 9701. (c) Feldman, K. S.; Romanelli, A. L.; Ruckle, Jr., R. E. J. Org. Chem. 1992, 57, 100. (d) Renaud, P.; Moufid, N.; Kuo, L. H.; Curran, D. P. J. Org. Chem. 1994, 59, 3547. (e) Renaud, P.; Bourquard, T.; Gerster, M.; Moufid, N. Angew. Chem., Int. Ed. Engl. 1994, 33, 1601. (f) Guindon, Y.; Guérin, B.; Chabot, C.; Mackintosh, N.; Ogilvie, W. W. Synlett 1995, 449. (g) Sibi, M. P.; Ji, J.; Hongliu, W.; Gürtler, S.; Porter, N. A. J. Am. Chem. Soc. 1996, 118, 9200 and references therein.
34. Presumably, this would also necessitate a matching between the chirality of the auxiliaries.
35. (a) Molander, G. A.; Kenny, C. Tetrahedron Lett. 1987, 28, 4367.
36. (b) Molander, G. A.; Kenny, C. J. Am. Chem. Soc. 1989, 111, 8236.
37. (c) Molander, G. A.; Kenny, C. J. Org. Chem. 1991, 56, 1439.
38. (d) Molander, G. A.; McKie, J. A. J. Org. Chem. 1992, 57, 3132.
39. (e) Kito, M.; Sakai, T.; Yamada K.; Matsuda, F.; Shirahama, H. Synlett 1993, 158.
40. (f) Molander, G. A.; McKie, J. A. J. Org. Chem. 1994, 59, 3186.
41. (g) Kan, R.; Nara, S.; Ito, S.; Matsuda, F.; Shirahama, H. J. Org. Chem. 1994, 59, 5111.
42. (h) Kan, T.; Hosokawa, S.; Nara, S.; Oikawa, M.; Ito, S.; Matsuda, F.; Shirahama, H. J. Org. Chem. 1994, 59, 5532.
43. (i) Molander, G. A.; McKie, J. A. J. Org. Chem. 1995, 60, 872.
44. Unpublished results.
45. Alternative explanations, such as an equilibrating cyclization process, although less probable, cannot be excluded.
46. 2-mediated reactions are known. For examples of ketyl-olefin coupling, see ref 5e,h. (a) Kawatsura, M.; Matsuda, F.; Shirahama, H. J. Org. Chem. 1994, 59, 6900. For a related example, see: (b) Inanaga, J.; Ujikawa, O.; Handa, Y.; Otsubo, K.; Yamaguchi, M. J. Alloys Compounds 1993, 192, 197.
47. 2-mediated reactions are known. For examples of ketyl-olefin coupling, see ref 5e,h. (a) Kawatsura, M.; Matsuda, F.; Shirahama, H. J. Org. Chem. 1994, 59, 6900. For a related example, see: (b) Inanaga, J.; Ujikawa, O.; Handa, Y.; Otsubo, K.; Yamaguchi, M. J. Alloys Compounds 1993, 192, 197.
48. For a review, see: (a) Alexakis, A.; Mangeney, P. Tetrahedron: Asymmetry 1990, 1, 477. For more recent work in this field, see: (b) Sammakia, T.; Smith, R. S. J. Am. Chem. Soc. 1992, 114, 10998, and references cited therein. (c) Aubé, J.; Heppert, J. A.; Milligan, M. L.; Smith, M. J.; Zenk P. J. Org. Chem. 1992, 57, 3563. (d) Parrain, J.-L.; Cintrat, J.-C.; Qintard, J.-P. J. Organomet. Chem. 1992, 437, C19. (e) Longobardo, L.; Mobbili, G.; Tagliavini, T.; Trombini, C.; Umani-Ronchi, A. Tetrahedron 1992, 48, 1299. (f) For a recent example of the application of chiral acetals to asymmetric cyclopropanations, see: Armstrong, R. W.; Maurer, K. W. Tetrahedron Lett. 1995, 36, 357.
49. For a review, see: (a) Alexakis, A.; Mangeney, P. Tetrahedron: Asymmetry 1990, 1, 477. For more recent work in this field, see: (b) Sammakia, T.; Smith, R. S. J. Am. Chem. Soc. 1992, 114, 10998, and references cited therein. (c) Aubé, J.; Heppert, J. A.; Milligan, M. L.; Smith, M. J.; Zenk P. J. Org. Chem. 1992, 57, 3563. (d) Parrain, J.-L.; Cintrat, J.-C.; Qintard, J.-P. J. Organomet. Chem. 1992, 437, C19. (e) Longobardo, L.; Mobbili, G.; Tagliavini, T.; Trombini, C.; Umani-Ronchi, A. Tetrahedron 1992, 48, 1299. (f) For a recent example of the application of chiral acetals to asymmetric cyclopropanations, see: Armstrong, R. W.; Maurer, K. W. Tetrahedron Lett. 1995, 36, 357.
50. For a review, see: (a) Alexakis, A.; Mangeney, P. Tetrahedron: Asymmetry 1990, 1, 477. For more recent work in this field, see: (b) Sammakia, T.; Smith, R. S. J. Am. Chem. Soc. 1992, 114, 10998, and references cited therein. (c) Aubé, J.; Heppert, J. A.; Milligan, M. L.; Smith, M. J.; Zenk P. J. Org. Chem. 1992, 57, 3563. (d) Parrain, J.-L.; Cintrat, J.-C.; Qintard, J.-P. J. Organomet. Chem. 1992, 437, C19. (e) Longobardo, L.; Mobbili, G.; Tagliavini, T.; Trombini, C.; Umani-Ronchi, A. Tetrahedron 1992, 48, 1299. (f) For a recent example of the application of chiral acetals to asymmetric cyclopropanations, see: Armstrong, R. W.; Maurer, K. W. Tetrahedron Lett. 1995, 36, 357.
51. For a review, see: (a) Alexakis, A.; Mangeney, P. Tetrahedron: Asymmetry 1990, 1, 477. For more recent work in this field, see: (b) Sammakia, T.; Smith, R. S. J. Am. Chem. Soc. 1992, 114, 10998, and references cited therein. (c) Aubé, J.; Heppert, J. A.; Milligan, M. L.; Smith, M. J.; Zenk P. J. Org. Chem. 1992, 57, 3563. (d) Parrain, J.-L.; Cintrat, J.-C.; Qintard, J.-P. J. Organomet. Chem. 1992, 437, C19. (e) Longobardo, L.; Mobbili, G.; Tagliavini, T.; Trombini, C.; Umani-Ronchi, A. Tetrahedron 1992, 48, 1299. (f) For a recent example of the application of chiral acetals to asymmetric cyclopropanations, see: Armstrong, R. W.; Maurer, K. W. Tetrahedron Lett. 1995, 36, 357.
52. For a review, see: (a) Alexakis, A.; Mangeney, P. Tetrahedron: Asymmetry 1990, 1, 477. For more recent work in this field, see: (b) Sammakia, T.; Smith, R. S. J. Am. Chem. Soc. 1992, 114, 10998, and references cited therein. (c) Aubé, J.; Heppert, J. A.; Milligan, M. L.; Smith, M. J.; Zenk P. J. Org. Chem. 1992, 57, 3563. (d) Parrain, J.-L.; Cintrat, J.-C.; Qintard, J.-P. J. Organomet. Chem. 1992, 437, C19. (e) Longobardo, L.; Mobbili, G.; Tagliavini, T.; Trombini, C.; Umani-Ronchi, A. Tetrahedron 1992, 48, 1299. (f) For a recent example of the application of chiral acetals to asymmetric cyclopropanations, see: Armstrong, R. W.; Maurer, K. W. Tetrahedron Lett. 1995, 36, 357.
53. For a review, see: (a) Alexakis, A.; Mangeney, P. Tetrahedron: Asymmetry 1990, 1, 477. For more recent work in this field, see: (b) Sammakia, T.; Smith, R. S. J. Am. Chem. Soc. 1992, 114, 10998, and references cited therein. (c) Aubé, J.; Heppert, J. A.; Milligan, M. L.; Smith, M. J.; Zenk P. J. Org. Chem. 1992, 57, 3563. (d) Parrain, J.-L.; Cintrat, J.-C.; Qintard, J.-P. J. Organomet. Chem. 1992, 437, C19. (e) Longobardo, L.; Mobbili, G.; Tagliavini, T.; Trombini, C.; Umani-Ronchi, A. Tetrahedron 1992, 48, 1299. (f) For a recent example of the application of chiral acetals to asymmetric cyclopropanations, see: Armstrong, R. W.; Maurer, K. W. Tetrahedron Lett. 1995, 36, 357.
54. Seebach, D.; Corey, E. J. J. Org. Chem. 1975, 40, 231.
55. Omura, K.; Swern, D. Tetrahedron 1978, 34, 1651.
56. Cresp, T. M.; Sargent, M. V.; Vogel, P. J. Chem. Soc., Perkin Trans. 1 1974, 37.
57. The diamide acetal 15 was produced as a 9:1 mixture ot E:Z stereoisomers. The mixture could be enriched by silica gel chromatography.
58. Stereoselectivity was determined by submitting crude reaction mixtures to p-TsOH in toluene heated at reflux. These conditions yielded quantifiable mixtures of 16 and 17 from the cyclization of enol ethers, 18 and 19. The relative Stereoselectivity was assumed to be trans based upon the cyclization of the achiral keto allylic acetal 20, which gave a 7:3 mixture of E- and Z-enol ethers rac-21. Submitting mixtures of 16-19 or rac-21 to hydrolysis conditions yielded the hydroxy aldehyde rac-22. The corresponding cis isomers would be expected to give a cyclic hemiacetal (vide infra). (Formula Presented)
59. 2/ THF-HMPA). (a) Molander, G. A.; Hahn, G. J. Org. Chem. 1986, 51, 1135. (b) Molander, G. A. Org. React. 1994, 46, 211.
60. 2/ THF-HMPA). (a) Molander, G. A.; Hahn, G. J. Org. Chem. 1986, 51, 1135. (b) Molander, G. A. Org. React. 1994, 46, 211.
61. The trans isomers, 25 and 26, made up less than 2% of the product mixture. The minor isomers were not isolated or characterized, and the ratio of 25:26 is unknown.
62. Nahm, S.; Weinreb, S. M. Tetrahedron Lett. 1981, 22, 3815.
63. (a) Lipton, M. F.; Basha, A.; Weinreb, S. M. In Organic Syntheses; Noland W. E., Ed.; John Wiley & Sons: New York. 1988; Collect. Vol. 6, pp 492-495.
64. (b) Basha, A.; Lipton, M.; Weinreb, S. M. Tetrahedron Lett. 1977, 4171.
65. Meyers, A. I.; Tomioka, K.; Fleming, M. P. J. Org. Chem. 1978, 43, 3788.
66. Tsunoda, T.; Suzuki, M.; Noyori, R. Tetrahedron Lett. 1980, 21, 1357.
67. These comments should be taken in the context of single run, unoptimized experiments.
68. Molander, G. A.; McWilliams, J. C., Tetrahedron Lett. 1996, 40, 7197.
69. (a) Knochel, P.; Yeh, M. C. P.; Berk, S. C.; Talbert, J. J. Org. Chem. 1988, 28, 351.
70. (b) For a recent review, see: Knochel, P.; Singer, R. D. Chem. Rev. 1993, 93, 2117.
71. Chong, J. M.; Wong, S. Tetrahedron Lett. 1986, 27, 5445.
72. Determined by GC after hydrolysis of the crude mixture (uncorrected for response factors).
73. The isolated yields of 15c and 15g were low overall, but this is a likely reflection of the isolation process. The relatively polar nature of the diamide acetals tends to swamp out subtleties in polarity differences between the impurities of this transformation (e.g., the chloride 44, iodide 45, and protonated material are all present in the crude mixture). For 15c, isolation from the crude mixture required a reduction to an isolable mixture of epimeric alcohols, followed by oxidation back to 15c. It should be noted that these yields represent single run, unoptimized reactions.
74. We have found that lithium anions derived from hydrazones will alkylate 45 in good yield at low temperatures (-78°C).
75. Stork, G.; Zhao, K. Tetrahedron Lett. 1989, 30, 287.
76. The stability of Sm(III)-ketyls derived from aromatic ketones is exemplified by the isolation and X-ray determination of the Sm(III)-ketyl derived from fluorenone: Hou, Z.; Miyano, T.; Yamazaki, H.; Wakatsuki, Y. J. Am. Chem. Soc. 1995, 117, 4421.
77. An analogous argument could be stated as a decrease in the electron density coefficient at the ketyl carbon orbital because of delocalization into the π-system.
78. 2 yielded 60:40 and 75:25 mixtures of 59/60, respectively. Also, the reactions appeared cleaner overall under these conditions.
79. The cyclization of phenyl-substituted ketyl radicals has been shown to be a reversible process. Furthermore, the Sm(III)-ketyl derived from fluorenone was found to undergo reversible pinacol coupling: ref 29.
80. When comparing the aldehyde substrate 15h to the aliphatic ketone substrates 15a-d, the rate of intermolecular pinacol coupling relative to cyclization is probably increased by diminished steric hindrance around the Sm(III)-ketyl, and this effect is compounded by the diminished nucleophilicity of the Sm(III)-ketyl.
81. In reality, a Boltzmann distribution of all reactive conformers would be more accurate, but with only semiquantitative approximations (i.e., energy approximations based upon correlation to related interactions), this is unworkable.
82. (a) Wiberg, K. B.; Martin, E. J. Am. Chem. Soc. 1985, 107, 5035.
83. (b) Dorigo, A. E.; Pratt, D. W.; Houk, K. N. J. Am. Chem. Soc. 1987, 109, 6591.
84. This is assuming an E2 elimination pathway.
85. Although greater interaction between the R group of the ketyl with the ligands around samarium is suggested, it is difficult to rationalize a switch from conformer 58 to 60 as the size of R gets larger (i.e., the diastereoselectivity of the cyclization decreases as the size of R increases).
86. McWilliams, J. C. Ph.D. Thesis, Cornell University, May, 1994.
87. Seebach, D.; Corey, E. J. J. Org. Chem. 1975, 40, 231.
88. Huurdeman, W. F. J.; Wynberg, H.; Emerson, D. W. Tetrahedron Lett. 1971, 3449.
89. Interestingly, the diastereoselectivity in the cyclization of 72 (≥99: 1), exceeded the isomeric purity of the starting alkene geometry (96:4). Because transition structures for the E-isomers cannot be applied to the Z-isomer, this implies a matched case for the transition state with which Z-72 cyclizes to yield 79 as well.
90. Low yields were generally obtained for all propargylic acetals examined (i.e., transacetalization with N,N,N′,N′-tetramethyl-L-tartaramide proceeded only at high temperatures and gave low yields of chiral products).
91. Corey, E. J.; Erickson, B. W. J. Org. Chem. 1971, 36, 3553.
92. This ratio of 27a/28a was calculated as follows: 27a/28a = (97 -0.3)/(3 - 1.7) = 99/1.