Synthesis

Biocatalytic Asymmetric Synthesis of (S)-and (R)-Timolol

G Tosi, F Zironi, E Caselli, A Forni, F Prati

Index: Tosi, Giovanni; Zironi, Federica; Caselli, Emilia; Forni, Arrigo; Prati, Fabio Synthesis, 2004 , # 10 p. 1625 - 1628

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Citation Number: 4

Abstract

Abstract A new biocatalytic route for the synthesis of both enantiomers of Timolol (1) is described. Starting from 3, 4-dichloro-1, 2, 5-thiadiazole (2),(R)-and (S)-Timolol (87% ee) were obtained in 35% and 30% overall yield, respectively. Asymmetric reduction of the intermediate haloketone 5 with baker's yeast afforded the corresponding halohydrin 6 in the optically active form (87% ee), which gave the R enantiomer (distomer) of Timolol. The S ...