THIOVALIDAMINE DERIVATIVES OF MANNO-TYPE AND GLUCO-TYPE - REMOTE ACTIVATION AND ANCHIMERIC ASSISTANCE

The oxazolidone (3) derived from validamine (1) was dithiocarbonylated , on treatment with NaH followed by CS2-MeI, to the N,O-dicarbodithioa te (6). On treatment with NaH-MeI, this afforded the manno-type thiova lidamine derivative (7) and then the gluco-type thiovalidamine derivat ive (8) following the pathway shown in Scheme 2: an activation at a C= S group by methylation, transferring this activation to a remote posit ion accompanied with decarboxylation, and cyclization of the neighbori ng group to the transferred position (C-3).