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

AbstractTo 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 (−)-(2S)-exo-hydroxycamphor (2a), (−)-(2S)-endo-hydroxycamphor (3a), (−)-(3S)-exo-hydroxycamphor (4a), (−)-(3S)-endo-hydroxycamphor (5a), and (+)-camphoric acid (6a). Compound 1b was converted to (+)-(2R)-exo-hydroxycamphor (2b), (+)-(2R)-endo-hydroxycamphor (3b), (+)-(3R)-exo-hydroxycamphor (4b), (+)-(3R)-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 confirmed by gas chromatography–mass spectrometry, infrared, 1H nuclear magnetic resonance (NMR), and 13C NMR spectral data. The products illustrate the marked ability of A. wentii for enzymatic oxidation and ketone reduction.