Hemisynthesis of bistramide D by stereoselective reduction of bistramide A. Partial determination of relative and absolute configurations

The hemisynthesis of bistramide D by stereoselective reduction of bistramide A is reported. The absolute configuration of C4 in bistramide D was also determined and the relative configurations of C6, C9 and C11 in the pyran part, as well as those of C22, C23, C27 and C31 in the spiro moiety of bistramides A and D were also determined by NMR.