Highly selective biotransformation of ( )-(1 S )- and ( )-(1 R )-camphorquinone by Aspergillus wentii

To clarify the structures of biotransformation products and metabolic pathways, the biotransformation of monoterpenoids, ( � )- and ( � )-camphorquinone ( 1a and b ), has been investigated using Aspergillus wentii as a biocatalyst. Compound 1a was converted to ( � )-(2 S )- exo -hydroxycamphor ( 2a ), ( � )-(2 S )- endo -hydroxycamphor ( 3a ), ( � )-(3 S )- exo -hydroxycamphor ( 4a ), ( � )-(3 S )- endo -hydroxycamphor ( 5a ), and ( � )-camphoric acid ( 6a ). Compound 1b was converted to ( � )-(2 R )- exo hydroxycamphor ( 2b ), ( � )-(2 R )- endo -hydroxycamphor ( 3b ), ( � )-(3 R )- exo -hydroxycamphor ( 4b ), ( � )-(3 R )- endo hydroxycamphor ( 5b ), and ( � )-camphoric acid ( 6b ). Compound 1a mainly produced 2a (65.0%) with stereoselectivity, whereas 1b afforded 3b (84.3%) with high stereoselectivity. These structures were confi rmed by gas chromatography ‐ mass spectrometry, infrared, 1 H nuclear magnetic resonance (NMR), and 13 C NMR spectral data. The products illustrate the marked ability of A. wentii for enzymatic oxidation and ketone reduction.