ENZYMATIC BAEYER-VILLIGER OXIDATIONS OF SOME BICYCLO[2.2.1]HEPTAN-2-ONES USING MONOOXYGENASES FROM PSEUDOMONAS-PUTIDA NCIMB-10007 - ENANTIOSELECTIVE PREPARATION OF A PRECURSOR OF AZADIRACHTIN

Two monooxygenases MO1 (NADH dependent) and MO2 (NADPH dependent) isolated from Ps. putida NCIMB 10007 [grown on(+)-camphor] have been utilized as biocatalysts in Baeyer-Villiger oxidations. The former enzyme oxidized the racemic ketones 9, la and 14 into the optically active lactones 15-17. The ketone 9 is not oxidized by MO2 but the ketones 10 and 14 gave the optically active lactones 16 and 17. Whole-cell preparations of Ps. putida degraded the ketone 9 but transformed the racemic ketones 10 and 14 into the optically active lactones 16 and 17. All the lactones possess the same absolute configuration: 1S, 5S, 6R. (+)-MO1 [the isozyme which metabolizes (+)-camphor], oxidized the ketone 10 but not the ketone 9. Conversely, (-)-MO1 [the isozyme which metabolizes (-)-camphor], catalysed the oxidation of the ketone 9 but not the ketone 10. Go-factor recycling was effected using dehydrogenase enzymes in preparative-scale experiments. The optically active lactone 17 is an intermediate in the synthesis of compound 5, an important precursor of azadirachtin 6.