Chemistry of Leucomycins. VIII. Absolute Configuration of Leucomycin and Isoleucomycin

Abstract

Structural relationship between demycarosyl-leucomycin-A₃ proposed through X-ray crystallography by Hiramatsu, et al. and leucomycin-A₃ was examined, and it was found that the hydroxyl group at the C-9 position on lactone of the latter underwent allylic rearrangement being transferred to the C-13 position in the former on mild hydrolysis of the latter with dilute hydrochloric acid. On the other hand, isoleucomycin-A₃, whose hydroxyl group at the C-13 position was transferred from C-9 in leucomycin-A₃ without liberation of mycarose portion, was obtained by warm acid treatment of leucomycin-A₃. Configuration on the C-9 position was determined by applying the benzoate or Mills' rule to leucomycin-A₃ and, from the present and previously reported results, the absolute structure of leucomycin-A₃ was elucidated.