Biotransformation of α-bromo and α,α′-dibromo alkanone to α-hydroxyketone and α-diketone by Spirulina platensis

Biotransformation of α-bromo and α,α′-dibromo alkanones were investigated with alga of Spirulina platensis. Biotransformation of α-bromo ketone with S. platensis gave the corresponding α-hydroxyketone in good yields (80–95%). It was found that α,α′-dibromo ketone biotransforms into α-diketone and then converts α-hydroxy ketone. However, in the case of diosphenol, it seems that alkyl group at the α-position of carbonyl group prevents reduction into α-hydroxy ketone. We compared to five algae (Cyanidioschyzon merolae, Cyanidium caldarium, Synechoccus elongatus PCC 7942, Synechosystis sp. PCC 6803 and S. platensis) for the biotransformation of 2-bromo cyclohaxanone (2). Among the algae, S. platensis gave the corresponding 2-hydroxycyclohexanone (2a) in best result (89% yield) for short reaction time (24 h). This reaction affords a new, eco-friendly and convenient method for α-hydroxyketones.