Abstract
The 2,3,4,6-tetra-O-[(tert-butyl)dimethylsilyl]-C-beta -D- galactopyranosylformaldehyde (2,6-anhydro-1,3,4,6-tetra-O-[(tert-butyl)dimethylsilyl]-D-glycero-L-man no-heptose, 2) was condensed with isolevoglucosenone (3) in the presene e of Et(2)AII to give 1,6-anhydro-3-C- {(1R)-2,6-anhydro-3,4,5,7-tetra-O-[(tert-butyl)dimethylsilyl]-D-glycero- L-manno-heptitol-1-C-yl}-2,3-dideoxy-beta -D-glycero-hex-2-enopyranos-4-ulose (8). Diastereoselective conjugate addition of BnONHBn to 8, followed by diastereoselective ketone reduction with LiBH4 and treatment with Me3SiSPh/ZnI2, provided phenyl 3-C-{(1R)-2,6-anhydro-3,4,5,7-tetra-O[(tert-butyl)dimethylsilyl]-D-glyce ro-L-manno-heptitol-1-C-yl}-2-[ (N-benzoxyl-N-benzyl)amino]-2,3-dideoxy-1-thio-beta -D-galacto-hexopyranoside (14).