Masaharu Sugiura

Lewis Acid Catalyzed Ring‐Opening Reactions of Sugar‐Derived Semicyclic N,O‐Acetals

N-(Alkoxycarbonyl)-N-glycosides (polyoxygenated semicyclic N,O-acetals) were efficiently synthesized from regular acetyl or methyl glycosides (glucopyranoside, ribofuranoside, arabinofuranoside, and 2-deoxyribofuranoside) and a carbamate by treatment of trimethylsilyl trifluoromethanesulfonate and 4u2005A molecular sieves. It was found that these N-glycosides underwent Lewis acid catalyzed ring-opening reactions with silylated nucleophiles to give ring-opened amino alcohols with good-to-high diastereoselectivity. The reactivity order, 2-deoxyribofuranoside > arabinofuranoside > ribofuranoside > glucopyranoside, was revealed. Ring-opening reductions were also investigated with silanes or diisobutylaluminium hydride. An appropriate reducing agent was found to be dependent on the N-glycosides used. A glycosidase inhibitor, (2S,3R,4R)-2-hydroxymethylpyrrolidine-3,4-diol (7) was synthesized by means of the reactions.

C–C Bond Formation Through Addition of C–M to C O, C N, and C N Bonds

This chapter covers carbon–carbon bond formations based on addition of organotransition metal compounds (C–M) to CO (carbonyl compounds and carbon dioxide), CN (imines and isocyanates), and CN (nitriles and isocyanides) bonds. A series of reactions reported between 1993 and 2005 are discussed comprehensively. Not only reactions using a stoichiometric amount of an organometallic compound but also catalytic processes are included, even though their catalytic mechanisms are only postulated in most cases.