A newefficientmethod of asymmetric synthesis of β-heterocycle substituted l-α-amino acids through the addition of 3-amino-1,2,4-thiodiazole and 5-mercapto-1,2,4-triazoles, containing various substituents at the 3 and 4 positions, to the CC bond of dehydroalanine in the Ni(II) complex of its Schiff base with (S)-2-N-(N′-benzylprolyl)aminobenzophenone has been elaborated upon. Under thermodynamic
Asymmetric synthesis of (R)-S-(1,2,4-triazol-3-yl)cysteines by nucleophilic addition of triazolethiols to a Ni<sup>II</sup>complex with a chiral dehydroalanine Schiff base
作者:A. S. Saghiyan、A. V. Geolchanyan、L. L. Manasyan、G. M. Mkrtchyan、N. R. Martirosyan、S. A. Dadayan、T. V. Kochickyan、V. S. Harutyunyan、A. A. Avetisyan、V. I. Tararov、V. I. Maleev、Yu. N. Belokon"
DOI:10.1023/b:rucb.0000037866.13065.c7
日期:2004.4
An efficient method was developed for the asymmetric synthesis of (R)-S-(1,2,4-triazol-3yl)cysteines by the addition of 3,4-disubstituted 1,2,4-triazole-5-thiols at the electrophilic C=C bond in a Ni-II complex of a Schiff base of dehydroalanine with (S)-N-(N-benzylprolyl)aminobenzophenone. The stereoselectivity of the formation of diastereomeric complexes with the (S,R) configuration under conditions of thermodynamic control of the nucleophilic addition exceeds 94%. Acid treatment of the reaction mixtures afforded enantiomerically pure (R)-S-hetarylcysteines (ee > 98%).