Sequential 11α-hydroxylation and 1-dehydrogenation of 16α-hydroxycortexolone

Two-step microbial transformation of 16α-hydroxycortexolone to its 1-dehydro-11α-hydroxy derivative, without isolating an intermediate, was achieved with an overall yield of 72% of product at a steroid substrate concentration of 3 mg/ml. The process included formation of the cycloborate complex of the substrate, hydroxylation of the borate complex with a suspension of Aspergillus ochraceus mycelium in phosphate buffer, and dehydrogenation of the 11α-hydroxylated intermediate with acetone-dried Arthrobacter simplex cells. The desired product was then obtained by breaking the resultant borate complex through acidification.