Kohji Ishihara¹, Mai Nishimura¹, Ken Nakashima¹, Noriko Machii¹, Fumie Miyake¹, Miyuki Nishi¹, Momoko Yoshida¹, Noriyoshi Masuoka¹ and Nobuyoshi Nakajima²

¹Department of Life Science, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan. ²Graduate School of Health and Welfare Science, Okayama Prefectural University, 111 Soja, Okayama 719-1197, Japan.

Abstract

The stereoselective reduction of an aromatic α-keto amide with actinomycete strains was investigated. It was found that 2-chlorobenzoylformamide was reduced to the corresponding 2-chloromandelamide by mesophilic and thermophilic strains of actinomycetes. Among the strains tested, the reduction of 2-chlorobenzoylformamide by Streptomyces thermocyaneoviolaceus (one of thermophilic strains) in the presence of glycerol as an additive produced only (S)-2-chloromandelamide in >99% conversion with >99% enantiomeric excess (e.e.). On the other hand, the reduction by Streptomyces thermocarboxydovorans NBRC16324 at 45 °C or Thermoactinomyces vulgaris NBRC15851 cultivated in a soluble starch-based medium gave the corresponding (R)-hydroxy amide (conversion, 99%; >99% e.e.). Mesophilic and other thermophilic actinomycete strains also catalyzed the reduction to the corresponding (R)-hydroxy amide with 85%–>99% e.e. Thus, the syntheses of both enantiomers of 2-chloromandelamide was achieved though the reduction of 2-chlorobenzoylformamide with different actinomycete strains.