A facile approach for the synthesis of pseudo-peptides incorporating a (2S,3R)-2-amino-cyclopropane carboxylic acid residue

Tetrahedron

Volumn 53, Issue 51, 1997, Pages 17417-17424

  Hibbs, David E ^c   Hursthouse, Michael B ^c   Jones, Iwan G ^a   Jones, Wyn ^b   Malik, K M Abdul ^c   North, Michael ^a  

^a BANGOR UNIVERSITY   (United Kingdom)

^b Peboc Div of Eastman Chemical Ltd   (United Kingdom)

^c CARDIFF UNIVERSITY   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

AMINO ACID; CYCLOPROPANECARBOXYLIC ACID DERIVATIVE; PSEUDOPEPTIDE;

ARTICLE; CONFORMATION; HYDROGEN BOND; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; PEPTIDE SYNTHESIS; PRIORITY JOURNAL; STEREOCHEMISTRY; X RAY CRYSTALLOGRAPHY;

EID: 0030733658     PISSN: 00404020     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4020(97)10165-X     Document Type: Article

References (39)

1. Biagini, S.C.G; North, M. 'Amino Acids, Peptides and Proteins Specialist Periodical Reports Vol. 27' (Davies, J.S Ed.); The Royal Society of Chemistry, 1996, Chapter 3; 'Peptide Secondary Structure Mimetics: Tetrahedron Symposia in Print Number 50' Kahn M (Ed.) Tetrahedron, 1993, 49, 3433-3689
2. Biagini, S.C.G; North, M. 'Amino Acids, Peptides and Proteins Specialist Periodical Reports Vol. 27' (Davies, J.S Ed.); The Royal Society of Chemistry, 1996, Chapter 3; 'Peptide Secondary Structure Mimetics: Tetrahedron Symposia in Print Number 50' Kahn M (Ed.) Tetrahedron, 1993, 49, 3433-3689
3. Horwell, D.C.; Naylor, D.; Willems, H.M.G. Bioorg. Med. Chem. Lett. 1997, 7, 31; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2853; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2847; Kobayashi, K.; Granja, J.R.; Ghadiri, M.R. Angew. Chem., Int. Ed. Engl. 1995, 34, 95; Tsang, K.Y.T.; Graciani, N.; Kelly, J.W. J. Am. Chem. Soc. 1994, 116, 3988; Tsang, K.Y.; Diaz, H.; Smith, A.B. III; Guzman, M.C.; Sprengeler, P.A.; Keenan, T.P.; Holcomb, R.C.; Wood, J.L.; Carroll, P.J.; Hirschmann, R. J. Am. Chem. Soc. 1994, 116, 9947; Giannis, A.; Kolter, T. Angew. Chem. Int. Ed. Engl. 1993, 32, 1244; Liang, G.-B.; Rito, C.J.; Gellman, S.H. J. Am. Chem. Soc. 1992, 114, 4440; Ernest, I.; J. Kalvoda, J.; Rihs, G.; Mutter, M. Tetrahedron Lett. 1990, 31, 4011; Kemp, D.S.; Bowen, B.R.; Muendal, C.C. J. Org. Chem. 1990, 55, 4650; Kemp, D.S.; Stites, W.E. Tetrahedron Lett. 1988, 29, 5057; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5077; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5081 and references cited in these papers.
4. Horwell, D.C.; Naylor, D.; Willems, H.M.G. Bioorg. Med. Chem. Lett. 1997, 7, 31; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2853; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2847; Kobayashi, K.; Granja, J.R.; Ghadiri, M.R. Angew. Chem., Int. Ed. Engl. 1995, 34, 95; Tsang, K.Y.T.; Graciani, N.; Kelly, J.W. J. Am. Chem. Soc. 1994, 116, 3988; Tsang, K.Y.; Diaz, H.; Smith, A.B. III; Guzman, M.C.; Sprengeler, P.A.; Keenan, T.P.; Holcomb, R.C.; Wood, J.L.; Carroll, P.J.; Hirschmann, R. J. Am. Chem. Soc. 1994, 116, 9947; Giannis, A.; Kolter, T. Angew. Chem. Int. Ed. Engl. 1993, 32, 1244; Liang, G.-B.; Rito, C.J.; Gellman, S.H. J. Am. Chem. Soc. 1992, 114, 4440; Ernest, I.; J. Kalvoda, J.; Rihs, G.; Mutter, M. Tetrahedron Lett. 1990, 31, 4011; Kemp, D.S.; Bowen, B.R.; Muendal, C.C. J. Org. Chem. 1990, 55, 4650; Kemp, D.S.; Stites, W.E. Tetrahedron Lett. 1988, 29, 5057; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5077; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5081 and references cited in these papers.
5. Horwell, D.C.; Naylor, D.; Willems, H.M.G. Bioorg. Med. Chem. Lett. 1997, 7, 31; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2853; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2847; Kobayashi, K.; Granja, J.R.; Ghadiri, M.R. Angew. Chem., Int. Ed. Engl. 1995, 34, 95; Tsang, K.Y.T.; Graciani, N.; Kelly, J.W. J. Am. Chem. Soc. 1994, 116, 3988; Tsang, K.Y.; Diaz, H.; Smith, A.B. III; Guzman, M.C.; Sprengeler, P.A.; Keenan, T.P.; Holcomb, R.C.; Wood, J.L.; Carroll, P.J.; Hirschmann, R. J. Am. Chem. Soc. 1994, 116, 9947; Giannis, A.; Kolter, T. Angew. Chem. Int. Ed. Engl. 1993, 32, 1244; Liang, G.-B.; Rito, C.J.; Gellman, S.H. J. Am. Chem. Soc. 1992, 114, 4440; Ernest, I.; J. Kalvoda, J.; Rihs, G.; Mutter, M. Tetrahedron Lett. 1990, 31, 4011; Kemp, D.S.; Bowen, B.R.; Muendal, C.C. J. Org. Chem. 1990, 55, 4650; Kemp, D.S.; Stites, W.E. Tetrahedron Lett. 1988, 29, 5057; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5077; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5081 and references cited in these papers.
6. Horwell, D.C.; Naylor, D.; Willems, H.M.G. Bioorg. Med. Chem. Lett. 1997, 7, 31; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2853; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2847; Kobayashi, K.; Granja, J.R.; Ghadiri, M.R. Angew. Chem., Int. Ed. Engl. 1995, 34, 95; Tsang, K.Y.T.; Graciani, N.; Kelly, J.W. J. Am. Chem. Soc. 1994, 116, 3988; Tsang, K.Y.; Diaz, H.; Smith, A.B. III; Guzman, M.C.; Sprengeler, P.A.; Keenan, T.P.; Holcomb, R.C.; Wood, J.L.; Carroll, P.J.; Hirschmann, R. J. Am. Chem. Soc. 1994, 116, 9947; Giannis, A.; Kolter, T. Angew. Chem. Int. Ed. Engl. 1993, 32, 1244; Liang, G.-B.; Rito, C.J.; Gellman, S.H. J. Am. Chem. Soc. 1992, 114, 4440; Ernest, I.; J. Kalvoda, J.; Rihs, G.; Mutter, M. Tetrahedron Lett. 1990, 31, 4011; Kemp, D.S.; Bowen, B.R.; Muendal, C.C. J. Org. Chem. 1990, 55, 4650; Kemp, D.S.; Stites, W.E. Tetrahedron Lett. 1988, 29, 5057; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5077; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5081 and references cited in these papers.
7. Horwell, D.C.; Naylor, D.; Willems, H.M.G. Bioorg. Med. Chem. Lett. 1997, 7, 31; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2853; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2847; Kobayashi, K.; Granja, J.R.; Ghadiri, M.R. Angew. Chem., Int. Ed. Engl. 1995, 34, 95; Tsang, K.Y.T.; Graciani, N.; Kelly, J.W. J. Am. Chem. Soc. 1994, 116, 3988; Tsang, K.Y.; Diaz, H.; Smith, A.B. III; Guzman, M.C.; Sprengeler, P.A.; Keenan, T.P.; Holcomb, R.C.; Wood, J.L.; Carroll, P.J.; Hirschmann, R. J. Am. Chem. Soc. 1994, 116, 9947; Giannis, A.; Kolter, T. Angew. Chem. Int. Ed. Engl. 1993, 32, 1244; Liang, G.-B.; Rito, C.J.; Gellman, S.H. J. Am. Chem. Soc. 1992, 114, 4440; Ernest, I.; J. Kalvoda, J.; Rihs, G.; Mutter, M. Tetrahedron Lett. 1990, 31, 4011; Kemp, D.S.; Bowen, B.R.; Muendal, C.C. J. Org. Chem. 1990, 55, 4650; Kemp, D.S.; Stites, W.E. Tetrahedron Lett. 1988, 29, 5057; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5077; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5081 and references cited in these papers.
8. Horwell, D.C.; Naylor, D.; Willems, H.M.G. Bioorg. Med. Chem. Lett. 1997, 7, 31; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2853; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2847; Kobayashi, K.; Granja, J.R.; Ghadiri, M.R. Angew. Chem., Int. Ed. Engl. 1995, 34, 95; Tsang, K.Y.T.; Graciani, N.; Kelly, J.W. J. Am. Chem. Soc. 1994, 116, 3988; Tsang, K.Y.; Diaz, H.; Smith, A.B. III; Guzman, M.C.; Sprengeler, P.A.; Keenan, T.P.; Holcomb, R.C.; Wood, J.L.; Carroll, P.J.; Hirschmann, R. J. Am. Chem. Soc. 1994, 116, 9947; Giannis, A.; Kolter, T. Angew. Chem. Int. Ed. Engl. 1993, 32, 1244; Liang, G.-B.; Rito, C.J.; Gellman, S.H. J. Am. Chem. Soc. 1992, 114, 4440; Ernest, I.; J. Kalvoda, J.; Rihs, G.; Mutter, M. Tetrahedron Lett. 1990, 31, 4011; Kemp, D.S.; Bowen, B.R.; Muendal, C.C. J. Org. Chem. 1990, 55, 4650; Kemp, D.S.; Stites, W.E. Tetrahedron Lett. 1988, 29, 5057; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5077; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5081 and references cited in these papers.
9. Horwell, D.C.; Naylor, D.; Willems, H.M.G. Bioorg. Med. Chem. Lett. 1997, 7, 31; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2853; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2847; Kobayashi, K.; Granja, J.R.; Ghadiri, M.R. Angew. Chem., Int. Ed. Engl. 1995, 34, 95; Tsang, K.Y.T.; Graciani, N.; Kelly, J.W. J. Am. Chem. Soc. 1994, 116, 3988; Tsang, K.Y.; Diaz, H.; Smith, A.B. III; Guzman, M.C.; Sprengeler, P.A.; Keenan, T.P.; Holcomb, R.C.; Wood, J.L.; Carroll, P.J.; Hirschmann, R. J. Am. Chem. Soc. 1994, 116, 9947; Giannis, A.; Kolter, T. Angew. Chem. Int. Ed. Engl. 1993, 32, 1244; Liang, G.-B.; Rito, C.J.; Gellman, S.H. J. Am. Chem. Soc. 1992, 114, 4440; Ernest, I.; J. Kalvoda, J.; Rihs, G.; Mutter, M. Tetrahedron Lett. 1990, 31, 4011; Kemp, D.S.; Bowen, B.R.; Muendal, C.C. J. Org. Chem. 1990, 55, 4650; Kemp, D.S.; Stites, W.E. Tetrahedron Lett. 1988, 29, 5057; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5077; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5081 and references cited in these papers.
10. Horwell, D.C.; Naylor, D.; Willems, H.M.G. Bioorg. Med. Chem. Lett. 1997, 7, 31; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2853; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2847; Kobayashi, K.; Granja, J.R.; Ghadiri, M.R. Angew. Chem., Int. Ed. Engl. 1995, 34, 95; Tsang, K.Y.T.; Graciani, N.; Kelly, J.W. J. Am. Chem. Soc. 1994, 116, 3988; Tsang, K.Y.; Diaz, H.; Smith, A.B. III; Guzman, M.C.; Sprengeler, P.A.; Keenan, T.P.; Holcomb, R.C.; Wood, J.L.; Carroll, P.J.; Hirschmann, R. J. Am. Chem. Soc. 1994, 116, 9947; Giannis, A.; Kolter, T. Angew. Chem. Int. Ed. Engl. 1993, 32, 1244; Liang, G.-B.; Rito, C.J.; Gellman, S.H. J. Am. Chem. Soc. 1992, 114, 4440; Ernest, I.; J. Kalvoda, J.; Rihs, G.; Mutter, M. Tetrahedron Lett. 1990, 31, 4011; Kemp, D.S.; Bowen, B.R.; Muendal, C.C. J. Org. Chem. 1990, 55, 4650; Kemp, D.S.; Stites, W.E. Tetrahedron Lett. 1988, 29, 5057; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5077; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5081 and references cited in these papers.
11. Horwell, D.C.; Naylor, D.; Willems, H.M.G. Bioorg. Med. Chem. Lett. 1997, 7, 31; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2853; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2847; Kobayashi, K.; Granja, J.R.; Ghadiri, M.R. Angew. Chem., Int. Ed. Engl. 1995, 34, 95; Tsang, K.Y.T.; Graciani, N.; Kelly, J.W. J. Am. Chem. Soc. 1994, 116, 3988; Tsang, K.Y.; Diaz, H.; Smith, A.B. III; Guzman, M.C.; Sprengeler, P.A.; Keenan, T.P.; Holcomb, R.C.; Wood, J.L.; Carroll, P.J.; Hirschmann, R. J. Am. Chem. Soc. 1994, 116, 9947; Giannis, A.; Kolter, T. Angew. Chem. Int. Ed. Engl. 1993, 32, 1244; Liang, G.-B.; Rito, C.J.; Gellman, S.H. J. Am. Chem. Soc. 1992, 114, 4440; Ernest, I.; J. Kalvoda, J.; Rihs, G.; Mutter, M. Tetrahedron Lett. 1990, 31, 4011; Kemp, D.S.; Bowen, B.R.; Muendal, C.C. J. Org. Chem. 1990, 55, 4650; Kemp, D.S.; Stites, W.E. Tetrahedron Lett. 1988, 29, 5057; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5077; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5081 and references cited in these papers.
12. Horwell, D.C.; Naylor, D.; Willems, H.M.G. Bioorg. Med. Chem. Lett. 1997, 7, 31; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2853; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2847; Kobayashi, K.; Granja, J.R.; Ghadiri, M.R. Angew. Chem., Int. Ed. Engl. 1995, 34, 95; Tsang, K.Y.T.; Graciani, N.; Kelly, J.W. J. Am. Chem. Soc. 1994, 116, 3988; Tsang, K.Y.; Diaz, H.; Smith, A.B. III; Guzman, M.C.; Sprengeler, P.A.; Keenan, T.P.; Holcomb, R.C.; Wood, J.L.; Carroll, P.J.; Hirschmann, R. J. Am. Chem. Soc. 1994, 116, 9947; Giannis, A.; Kolter, T. Angew. Chem. Int. Ed. Engl. 1993, 32, 1244; Liang, G.-B.; Rito, C.J.; Gellman, S.H. J. Am. Chem. Soc. 1992, 114, 4440; Ernest, I.; J. Kalvoda, J.; Rihs, G.; Mutter, M. Tetrahedron Lett. 1990, 31, 4011; Kemp, D.S.; Bowen, B.R.; Muendal, C.C. J. Org. Chem. 1990, 55, 4650; Kemp, D.S.; Stites, W.E. Tetrahedron Lett. 1988, 29, 5057; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5077; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5081 and references cited in these papers.
13. Horwell, D.C.; Naylor, D.; Willems, H.M.G. Bioorg. Med. Chem. Lett. 1997, 7, 31; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2853; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2847; Kobayashi, K.; Granja, J.R.; Ghadiri, M.R. Angew. Chem., Int. Ed. Engl. 1995, 34, 95; Tsang, K.Y.T.; Graciani, N.; Kelly, J.W. J. Am. Chem. Soc. 1994, 116, 3988; Tsang, K.Y.; Diaz, H.; Smith, A.B. III; Guzman, M.C.; Sprengeler, P.A.; Keenan, T.P.; Holcomb, R.C.; Wood, J.L.; Carroll, P.J.; Hirschmann, R. J. Am. Chem. Soc. 1994, 116, 9947; Giannis, A.; Kolter, T. Angew. Chem. Int. Ed. Engl. 1993, 32, 1244; Liang, G.-B.; Rito, C.J.; Gellman, S.H. J. Am. Chem. Soc. 1992, 114, 4440; Ernest, I.; J. Kalvoda, J.; Rihs, G.; Mutter, M. Tetrahedron Lett. 1990, 31, 4011; Kemp, D.S.; Bowen, B.R.; Muendal, C.C. J. Org. Chem. 1990, 55, 4650; Kemp, D.S.; Stites, W.E. Tetrahedron Lett. 1988, 29, 5057; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5077; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5081 and references cited in these papers.
14. Horwell, D.C.; Naylor, D.; Willems, H.M.G. Bioorg. Med. Chem. Lett. 1997, 7, 31; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2853; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2847; Kobayashi, K.; Granja, J.R.; Ghadiri, M.R. Angew. Chem., Int. Ed. Engl. 1995, 34, 95; Tsang, K.Y.T.; Graciani, N.; Kelly, J.W. J. Am. Chem. Soc. 1994, 116, 3988; Tsang, K.Y.; Diaz, H.; Smith, A.B. III; Guzman, M.C.; Sprengeler, P.A.; Keenan, T.P.; Holcomb, R.C.; Wood, J.L.; Carroll, P.J.; Hirschmann, R. J. Am. Chem. Soc. 1994, 116, 9947; Giannis, A.; Kolter, T. Angew. Chem. Int. Ed. Engl. 1993, 32, 1244; Liang, G.-B.; Rito, C.J.; Gellman, S.H. J. Am. Chem. Soc. 1992, 114, 4440; Ernest, I.; J. Kalvoda, J.; Rihs, G.; Mutter, M. Tetrahedron Lett. 1990, 31, 4011; Kemp, D.S.; Bowen, B.R.; Muendal, C.C. J. Org. Chem. 1990, 55, 4650; Kemp, D.S.; Stites, W.E. Tetrahedron Lett. 1988, 29, 5057; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5077; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5081 and references cited in these papers.
15. Horwell, D.C.; Naylor, D.; Willems, H.M.G. Bioorg. Med. Chem. Lett. 1997, 7, 31; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2853; Kim, K.; Germanas, J.P. J. Org. Chem. 1997, 62, 2847; Kobayashi, K.; Granja, J.R.; Ghadiri, M.R. Angew. Chem., Int. Ed. Engl. 1995, 34, 95; Tsang, K.Y.T.; Graciani, N.; Kelly, J.W. J. Am. Chem. Soc. 1994, 116, 3988; Tsang, K.Y.; Diaz, H.; Smith, A.B. III; Guzman, M.C.; Sprengeler, P.A.; Keenan, T.P.; Holcomb, R.C.; Wood, J.L.; Carroll, P.J.; Hirschmann, R. J. Am. Chem. Soc. 1994, 116, 9947; Giannis, A.; Kolter, T. Angew. Chem. Int. Ed. Engl. 1993, 32, 1244; Liang, G.-B.; Rito, C.J.; Gellman, S.H. J. Am. Chem. Soc. 1992, 114, 4440; Ernest, I.; J. Kalvoda, J.; Rihs, G.; Mutter, M. Tetrahedron Lett. 1990, 31, 4011; Kemp, D.S.; Bowen, B.R.; Muendal, C.C. J. Org. Chem. 1990, 55, 4650; Kemp, D.S.; Stites, W.E. Tetrahedron Lett. 1988, 29, 5057; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5077; Kemp, D.S.; Bowen, B.R. Tetrahedron Lett. 1988, 29, 5081 and references cited in these papers.
16. For a preliminary communication see: Jones, I.G.; Jones, W.; North, M.; Teijeira, M.; Uriarte, E. Tetrahedron Lett., 1997, 38, 889.
17. Another synthesis of β-amino cyclopropane carboxylic acid derivatives designed as β-turn mimics has recently been reported: Voigt, J.; Noltemeyer, M.; Reiser, O. Synlett, 1997, 202; Bubert, C.; Cabrele, C.; Reiser, O. Synlett, 1997, 827.
18. Another synthesis of β-amino cyclopropane carboxylic acid derivatives designed as β-turn mimics has recently been reported: Voigt, J.; Noltemeyer, M.; Reiser, O. Synlett, 1997, 202; Bubert, C.; Cabrele, C.; Reiser, O. Synlett, 1997, 827.
19. Salaun, J.; Baird, M.S. Curr. Med. Chem., 1995, 2, 511; Burgess, K.; Ho, K-K.; Moye-Sherman, D. Synlett, 1994, 575; Stammer, C.H. Tetrahedron, 1990, 46, 2231.
20. Salaun, J.; Baird, M.S. Curr. Med. Chem., 1995, 2, 511; Burgess, K.; Ho, K-K.; Moye-Sherman, D. Synlett, 1994, 575; Stammer, C.H. Tetrahedron, 1990, 46, 2231.
21. Salaun, J.; Baird, M.S. Curr. Med. Chem., 1995, 2, 511; Burgess, K.; Ho, K-K.; Moye-Sherman, D. Synlett, 1994, 575; Stammer, C.H. Tetrahedron, 1990, 46, 2231.
22. Zhang, Z.H.; Schofield, C.J.; Baldwin, J.E.; Thomas, P.; John, P. Biochem. J., 1995, 307, 77 and references cited therein.
23. Kaufman, M.D.; Grieco, P.A. J. Org. Chem., 1994, 59, 7179; Paulini, K.; Reibig, H-U. Liebigs Ann. Chem., 1991, 455; Cannon, J.G.; Garst, J.E. J. Org. Chem., 1975, 40, 182; Gebhardt-Schmitz, A.; Mennicken, H.; Schmitz, F.; Lipp, P.; Lipp, M. Tetrahedron Lett., 1962, 227.
24. Kaufman, M.D.; Grieco, P.A. J. Org. Chem., 1994, 59, 7179; Paulini, K.; Reibig, H-U. Liebigs Ann. Chem., 1991, 455; Cannon, J.G.; Garst, J.E. J. Org. Chem., 1975, 40, 182; Gebhardt-Schmitz, A.; Mennicken, H.; Schmitz, F.; Lipp, P.; Lipp, M. Tetrahedron Lett., 1962, 227.
25. Kaufman, M.D.; Grieco, P.A. J. Org. Chem., 1994, 59, 7179; Paulini, K.; Reibig, H-U. Liebigs Ann. Chem., 1991, 455; Cannon, J.G.; Garst, J.E. J. Org. Chem., 1975, 40, 182; Gebhardt-Schmitz, A.; Mennicken, H.; Schmitz, F.; Lipp, P.; Lipp, M. Tetrahedron Lett., 1962, 227.
26. Kaufman, M.D.; Grieco, P.A. J. Org. Chem., 1994, 59, 7179; Paulini, K.; Reibig, H-U. Liebigs Ann. Chem., 1991, 455; Cannon, J.G.; Garst, J.E. J. Org. Chem., 1975, 40, 182; Gebhardt-Schmitz, A.; Mennicken, H.; Schmitz, F.; Lipp, P.; Lipp, M. Tetrahedron Lett., 1962, 227.
27. Godier-Marc, E.; Aitken, D.J., Husson, H-P. Tetrahedron Lett., 1997, 38, 4065.
28. North, M.; Zagotto, G. Synlett, 1995, 639; Albers, T.; Biagini, S.C.G.; Hibbs, D.E.; Hursthouse, M.B.; Malik, K.M.A.; North, M.; Uriarte, E.; Zagotto, G. Synthesis, 1996, 393; Jones, I.G.; Jones, W.; North, M. Synlett, 1997, 63.
29. North, M.; Zagotto, G. Synlett, 1995, 639; Albers, T.; Biagini, S.C.G.; Hibbs, D.E.; Hursthouse, M.B.; Malik, K.M.A.; North, M.; Uriarte, E.; Zagotto, G. Synthesis, 1996, 393; Jones, I.G.; Jones, W.; North, M. Synlett, 1997, 63.
30. North, M.; Zagotto, G. Synlett, 1995, 639; Albers, T.; Biagini, S.C.G.; Hibbs, D.E.; Hursthouse, M.B.; Malik, K.M.A.; North, M.; Uriarte, E.; Zagotto, G. Synthesis, 1996, 393; Jones, I.G.; Jones, W.; North, M. Synlett, 1997, 63.
31. Anderson, G.W.; Callahan, F.M. J. Am. Chem. Soc., 1960, 82, 3359.
32. The authors have deposited the atomic coordinates for 6a with the Cambridge Crystallographic Data Centre. The coordinates can be obtained, on request, from the Director, Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK.
33. Shioiri, T. In Comprehensive Organic Synthesis, Trost, B.M.; Fleming, I.; and Winterfeldt, E., Eds., Pergamon, Oxford, 1991, vol. 3, p806; Arai, Y.; Kawanami, S.; Koizumi, T. J. Chem. Soc., Perkin Trans. I. 1991, 2969.
34. Shioiri, T. In Comprehensive Organic Synthesis, Trost, B.M.; Fleming, I.; and Winterfeldt, E., Eds., Pergamon, Oxford, 1991, vol. 3, p806; Arai, Y.; Kawanami, S.; Koizumi, T. J. Chem. Soc., Perkin Trans. I. 1991, 2969.
35. Zeggaf, C.; Poncet, J.; Jouin, P.; Dufour, M-N.; Castro, B. Tetrahedron 1989, 45, 5039.
36. Still, W.C.; Kahn, M.; Mitra, A. J. Org. Chem., 1978, 43, 2923.
37. Darr, J.A.; Drake, S.R.; Hursthouse, M.B.; Malik, K.M.A. Inorg. Chem. 1993, 32, 5704.
38. Sheldrick, G.M. Acta Crystallogr. 1990, A46, 467.
39. Sheldrick, G.M. 'SHELXL93 Program for Crystal Structure Refinement' University of Gottingen, Germany, 1993.