AN EFFICIENT SYNTHESIS OF A KEY INTERMEDIATE OF DU-6859A VIA ASYMMETRIC MICROBIAL REDUCTION

An efficient synthetic method for the C-7 substituent of DU-6859a (1), which is a new-generation antibacterial quinolone carboxylic acid, wa s established by utilizing an enantioselective microbial reduction of 5-benzyl-3,7-dioxo-5-azaspiro[2.4]heptane (7) to the corresponding chi ral alcohol (8) as the key reaction. This synthetic method was based o n use of AIPHOS (Artificial Intelligence for Planning and Handling Org anic Synthesis), which is a synthesis design system that generates sui table retrosynthetic routes from the standpoints of both novelty and p racticality.