Branched-chain sugars. XXXVI. A new synthesis of methyl 4-O-benzoyl-3-benzoylamino-2,3,6-trideoxy-3-C-methyl-.ALPHA.-L-xylo-hexopyranoside, a derivative of the branched-chain amino sugar of antibiotic A35512B.

The title compound was synthesized from methyl 4-O-benzyl-2,6-dideoxy-β-L-threo-hexopyranosid-3-ulose (19) through cyanomesylation, reductive spiro aziridine formation, and reductive ring-opening. When (2-methoxyethoxymethyl) group was used as the protecting group at O-4 of the above intermediate, it could not be removed at the final stage.