Asymmetric Synthesis of α,β-Dialkyl-α-phenylalanines via Direct Alkylation of a Chiral Alanine Derivative with Racemic α-Alkylbenzyl Bromides. A Case of High Enantiomer Differentiation at Room Temperature

Organic Letters

Volumn 3, Issue 3, 2001, Pages 341-343

  Soloshonok, Vadim A ^a   Tang, Xuejun ^a   Hruby, Victor J ^a   Van Meervelt, Luc ^b  

^a University of Arizona   (United States)

^b UNIVERSITY OF LEUVEN   (Belgium)

Author keywords

[No Author keywords available]

Indexed keywords

ALANINE; BROMINATED HYDROCARBON; DRUG DERIVATIVE; PHENYLALANINE;

ALKYLATION; ARTICLE; CHEMISTRY; STEREOISOMERISM; SYNTHESIS; TEMPERATURE;

ALANINE; ALKYLATION; HYDROCARBONS, BROMINATED; PHENYLALANINE; STEREOISOMERISM; TEMPERATURE;

EID: 0035825745     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol000330o     Document Type: Article

References (25)

1. For definition of "tailor-made amino acids", see footnote 2 in the following: Soloshonok, V. A.; Cai, C.; Hruby, V. J.; Meervelt, L. Tetrahedron 1999, 55, 12045.
2. For general reviews on asymmetric synthesis of α-amino acids, see: (a) Cativiela, C.; Diaz-de-Villegas, M. D. Tetrahedron: Asymmetry 1998, 9, 3517. (b) Cativiela, C.; Diaz-de-Villegas, M. D. Tetrahedron: Asymmetry 2000, 11, 654. (c) Duthaler, R. O. Tetrahedron 1994, 50, 1539. (d) Williams, R. M. Synthesis of Optically Active α-Amino Acids; Pergamon Press: Oxford, 1989.
3. For general reviews on asymmetric synthesis of α-amino acids, see: (a) Cativiela, C.; Diaz-de-Villegas, M. D. Tetrahedron: Asymmetry 1998, 9, 3517. (b) Cativiela, C.; Diaz-de-Villegas, M. D. Tetrahedron: Asymmetry 2000, 11, 654. (c) Duthaler, R. O. Tetrahedron 1994, 50, 1539. (d) Williams, R. M. Synthesis of Optically Active α-Amino Acids; Pergamon Press: Oxford, 1989.
4. For general reviews on asymmetric synthesis of α-amino acids, see: (a) Cativiela, C.; Diaz-de-Villegas, M. D. Tetrahedron: Asymmetry 1998, 9, 3517. (b) Cativiela, C.; Diaz-de-Villegas, M. D. Tetrahedron: Asymmetry 2000, 11, 654. (c) Duthaler, R. O. Tetrahedron 1994, 50, 1539. (d) Williams, R. M. Synthesis of Optically Active α-Amino Acids; Pergamon Press: Oxford, 1989.
5. For general reviews on asymmetric synthesis of α-amino acids, see: (a) Cativiela, C.; Diaz-de-Villegas, M. D. Tetrahedron: Asymmetry 1998, 9, 3517. (b) Cativiela, C.; Diaz-de-Villegas, M. D. Tetrahedron: Asymmetry 2000, 11, 654. (c) Duthaler, R. O. Tetrahedron 1994, 50, 1539. (d) Williams, R. M. Synthesis of Optically Active α-Amino Acids; Pergamon Press: Oxford, 1989.
6. (a) Molecular Conformation and Biological Interactions; Balaram, P., Ramaseshan, S., Eds.; Indian Academy of Science: Bangalore, 1991.
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11. (a) Hruby, V. J.; Li, G.; Haskell-Luevano, C.; Shenderovich, M. Biopolymers (Peptide Science) 1997, 43, 219.
12. (b) Hruby, V. J. Life Sci. 1982, 31, 189.
13. (c) Nicolás, E.; Dharanipragada, R.; Tóth, G.; Hruby, V. J. Tetrahedron Lett. 1989, 30, 6841.
14. (d) Hruby, V. J.; Slate, C. In Advances in Amino Acid Mimetics and Peptidomimetics; Abell, A., Ed.; JAI Press Inc.: Greenwich, 1999; pp 191-220.
15. (a) Davis, F. A.; Liang, C.-H.; Liu, H. J. Org. Chem. 1997, 62, 3796.
16. (b) Davis, F. A.; Liu, H.; Zhou, P.; Fang, T.; Reddy, G. V.; Zhang, Y. J. Org. Chem. 1999, 64, 7559.
17. Kazmierski, W. M.; Urbanczyk-Lipkowska, Z.; Hruby, V. J. J. Org. Chem. 1994, 59, 1789.
18. A Ni(II)-complex of the chiral Schiff base of alanine with (S)-o-[N-(N-benzylprolyl)amino]benzophenone (1) was available from a previous study: Qiu, W.; Soloshonok, V. A.; Cai, C.; Tang, X.; Hruby, V. J. Tetrahedron 2000, 56, 2577.
19. rac-1-Bromo-1-phenylethane (1a) is commercially available; the other 1-bromo-1-phenylalkanes (1b,c) were prepared by dehydroxybromination of the corresponding benzylic alcohols; see the Supporting Information.
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22. Complex 1 prepared from racemic alanine and chiral ligand (S)-6 (see Scheme 1) was obtained and used as a mixture of (S)(α-S) and (S)-(α-A) diastereomers in a ratio of 9 to 1.
23. Ligand (S)-6, isolated stereochemically intact, was readily transformed to the starting Ni(II)-complex (S)(S,R)-1.
24. For details on determination of the absolute configuration of the α-stereogenic center in complexes of type 3 and 4, see: Soloshonok, V. A.; Cai, C.; Hruby, V. J.; Meervelt, L. V.; Mischenko, N. Tetrahedron 1999, 55, 12031.
25. See footnote d in Table 1.