Reduction of (+)- and (−)-camphorquinones by cyanobacteria

Reduction of (+)- and (−)-camphorquinones (1a, 1b) by cyanobacteria (Synechococcus elongatus PCC 7942 and Synechosystis sp. PCC 6803) under illumination gave α-hydroxycamphor selectively. It was found that (+)-camphorquinone was reduced to give (−)-3S-exo-hydroxycamphor as major product in high stereoselectivity and the stereoselectivity decreased in the dark.