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Zeitschrift für Naturforschung B Contents Vol. 69b (2014)

Z. Naturforsch. 2014, 69b, 451 – 460

doi:10.5560/ZNB.2014-3221

Asymmetric Synthesis of Enantiomerically Enriched α-Amino Acids Containing 2-Furyl- and 2-Thienyl-1,2,4-triazoles in the Side-Chain

Ashot S. Saghyan^1,2, Hayarpi M. Simonyan², Satenik G. Petrosyan², Anna F. Mkrtchyan¹, Lilit V. Khachatryan², Arpine V. Geolchanyan^1,2, Melanya A. Samvelyan², Tariel V. Ghochikyan², Nazken Kelzhanova^3,4, Amanzhan T. Saginayev⁵, and Peter Langer^3,4

¹Scientific and Production Center “Armbiotechnology” of NAS RA, 14 Gyurjyan Str., 0056 Yerevan, Armenia

²Department of Pharmaceutical Chemistry, Yerevan State University, 1 A, Manoogian Str., 0025 Yerevan, Armenia

³Institute of Chemistry, University of Rostock, Albert-Einstein-Str. 3a, 18059 Rostock, Germany

⁴Leibniz Institute of Catalysis at the University of Rostock e. V. (LIKAT), Albert-Einstein-Str. 29a, 18059 Rostock, Germany

⁵Atyrau Institute of Oil and Gas, Atyrau, Republic of Kazakhstan

Reprint requests to Prof. Peter Langer. Fax: +381 4986412. E-mail: peter.langer@uni-rostock.de

Received August 12, 2013 / published online April 7, 2014

An efficient method for the asymmetric synthesis of α-amino acids, containing furyl- and thiophenyl-substituted triazoles in their side-chain, is reported. The strategy relies on Michael addition of 3,4,5-substituted 1,2,4-triazoles to the C=C bond of chiral Ni^II complexes containing the Schiff base formed from dehydroamino acids (dehydroalanine and (E + Z)-dehydroaminobutyric acid) and from chiral auxiliaries, i. e. (S)-2-N-(N′-benzylprolyl)aminobenzophenone and (S)-2-N-(N′-2-chlorobenzylprolyl) aminobenzophenone. The reactions proceeded with good to very good diastereoselectivity. Hydrolysis of the diastereomeric mixtures of metal complexes afforded the enantiomerically pure α-amino acids with high enantiomeric excess (ee >% 98).

Key words: Asymmetric Synthesis, Amino Acids, Chiral Ni^II Complexes, Heterocycles

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