Synthetic studies on antibiotic validamycins. Part 14. Total synthesis of (+)-validamycins C, D and F

Abstract

(+)-Validamycins C and F were first completely synthesised by use of a common blocked derivative 5 of (+)-validoxylamine A. The diols 6 and 7, obtained by acid hydrolysis of 5, were appropriately protected to give the aglycones 17, 25 and 30, which were condensed with glycosyl donor 11 or 19 to afford the condensates 20 and 26, being convertible, by deprotection and acetylation, to the totally O-acetylated derivates 21 and 33 of validamycins C and F, respectively. In addition, (+)-validamycin D was first synthesised by α-glycosylation of the protected derivative 37 of validoxylamine A.