Pichia terricola reduction with

Similar reduction of a prochiral diketone C with another yeast, Pichia terricola afforded D, which was converted to JH I,28 JH II,28 JH 029 and 4-methyl JH I.30 In the case of (+)-4-methyl JH I, asymmetric hydrolysis of dimethyl 3-methylglutarate with pig-liver esterase (PLE) was also employed for its... 

Figure 3.9 summarizes our synthesis of the enantiomers of JH I in 1988.28 If we want to employ the same strategy as used for the synthesis of JH III, the synthesis of JH I demands the execution of the diastereo-and enantioselective reduction of a prochiral 1,3-diketone A. Unfortunately, reduction of A with fermenting baker s yeast was nondiastereoselective, giving both B and C. After extensive screening of yeasts, Pichia terricola KI 0117 donated by Kirin Brewery Co. was found to achieve highly stereoselective reduction to give >99% of B with 99% ee. Since both of the 3,5-dinitrobenzoates D and E were crystalline, these could be purified by recrystallization, and 100% pure E was secured. Conversion of E to F was achieved by methanolysis followed by acetonide formation. The enantiomeric purity of F was proved to be ca. 100% ee by HPLC analysis of bis-MTPA ester G derived from F. 

The ability of yeasts such as baker s yeast Saccharomyces cerevisiae) was utilized extensively by chemists to reduce carbonyl compounds to alcohols [70,71]. 2,2-Dimethylcy-clohexane-l,3-dione (56) can be reduced with fermenting baker s yeast to give the (5)-hydroxy ketone 5 (Fig. 27), which was employed extensively in terpene synthesis as shown in Fig. 5 [23]. Diastereo- and enantioselective reduction of 57 Wiih Pichia terricola KI 0117 yielded 6 (Fig. 27) [35], which was converted to both (+)-JH I [35] and (—)-JH I [72,73] (Fig. 6). Reduction of 57 with baker s yeast was nondiastereoselective [35]. 

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