Efforts to resolve the problems of low yields of (R)-TSA
from natural sources and difficulties in achieving its total
synthesis have resulted in a simple four-step strategy being
devised for the synthesis of achiral amide analogues of the
natural product. The analogues consisted of a hydroxamate
function, a benzamide, and an aliphatic spacer, with maximal
inhibitory activity being observed with a five-carbon linker
chain.221 The resulting lead compound was 6-(4-dimethylaminobenzoyl)aminocaproic
acid hydroxamide (75; Scheme
16), and though the anti-tumor and cell transduction activities
of these compounds have been reported, no in vivo data has
yet been published