Synthetic studies on antibiotic validamycins. Part 12. Total synthesis of (+)-validamycin B and (+)-validoxylamine B

Abstract

The first complete synthesis of validamycin B (1a) and validoxylamine B (2a) is reported; coupling of the epoxide (12) and the partially protected derivative (16) of (+)-valienamine, followed by deprotection, gives (1a), which was identified from the ¹H n.m.r. spectrum of its totally O-acetylated derivative (1b). Alternatively, coupling of the epoxide (24) with the amine (16) affords compound (25), the structure of which can be established by converting (25) into validoxylamine B nona-O-acetate (2b). The appropriately protected amine (29) derived from (25) is glycosylated, followed by deprotection and acetylation, to give (1b).