BIOLOGICAL ENANTIOSELECTIVE REDUCTION OF METHYLCYCLOHEXANONES BY GLOMERELLA-CINGULATA

Biological reduction of alkylcyclohexanones by Glomerella cingulata wa s studied. With this organism regioisomeric 2-, 3- or 4-methylcyclohex anone gave the corresponding cis- and trans-methylcyclohexanols. The m ajor metabolites of (+/-)-2- and (+/-)-3-methylcyclohexanone were cis- 2- and cis-3-methylcyclohexanol. On the other hand, 4-methylcyclohexan one yielded mainly the trans-4-methylcyclohexanol. In addition, the me tabolites from (+/-)-2- and (+/-)-3-methylcyclohexanone indicated enan tioselective reduction by specific optical rotation of the products. T he enantiomeric excesses of the microbiological reduction products wer e determined by NMR spectra of (+)-MTPA-esters of the alcohols produce d. The reduction of (+/-)-2-methylcyclohexanone was stereospecific, wi th the (2R)-ketone being converted to the corresponding (+)-cis-2-meth ylcyclohexanol (1S-2R); absolute configuration, 92% e.e. On the other hand, the enantiomeric excess of the major metabolite of (+/-)-3-methy lcyclohexanone was (-)-cis-3-methylcyclohexanol (1S-3R); absolute conf iguration, 33% e.e.