面包酵母不对称还原酮

面包酵母作为生物催化剂还原潜手性的酮构建手性中心的反应，近几年在有机合成中得到广泛的应用。最初面包酵母的应用是1898年将糠醛还原为糠醇，之后经Macleod和Hub的研究拓宽了这一反应的应用。近几十年对于此反应在水相进而在有机相中反应取得进展，越来越多的有机合成化学家考虑应用酵母还原反应底物制备重要的手性医药中间体。

酵母还原有以下特点：高度专一的立体选择性；反应温和反应速率快；还原反应收率高，成本低；符合绿色化学要求，环境友好。

反应应用

合成芬氟拉明的重要中间体(J. Org. Chem. 1991,56,6019)：

托莫西汀类似物的手性中心构建(Indian J. Chem. 1992,31B, 803)：

j酵母还原 Ethyl Acetoacetate: (S)-( + )-Ethyl 3-Hydroxybutanoate ( Organic Syntheses, Coll.Vol. 7, p.215; Vol. 63, p.1):

A 4-L,three-necked, round-bottomed flask equipped with mechanicalstirrer, bubble counter, and a stopper is charged with 1.6 L of tap water, 300 g of ,and 200 g of baker's yeast, which are added with stirring in this order. Themixture is stirred for 1 hr at about 30°C, 20.0 g (0.154mol) of is added, and the fermenting suspension  is stirred for another 24 hr at roomtemperature. A warm (ca. 40°C) solution of 200 g of   in 1 Lof tap water is then added, followed 1 hr later by an additional 20.0 g (0.154 mol) of . Stirring is continued for 50–60 hr at roomtemperature. When the reaction is complete by gas chromatographic analysis, themixture is worked up by first adding 80 g of Celite and filtering through a sintered-glass funnel (porosity 4, 17-cm diam). Afterthe filtrate is washed with 200 mL of water, it is saturated with and extracted with five 500-mL portions of . The combined extracts are dried over , filtered, and concentrated with a rotaryevaporator at 35°C bath temperature to a volume of 50–80 mL. Thisresidue is fractionally distilled at a pressure of 12 mm through a 10-cm Vigreux column, and the fraction boiling at 71–73°C (12 mm) is collected to give 24–31 g (59–76%) of ; thespecific rotation [α]²⁵D + 37.2° (,c 1.3) corresponds to an enantiomeric excess of 85%.

The enantiomeric excessmay be enhanced by several crystallizations of the 3,5-dinitrobenzoatederivative or else by using "starved" yeast.