Gold(I)-Catalyzed Glycosylation with Glycosyl o -Alkynylbenzoates as Donors

作者：Biao Yu · 发表于：Accounts of Chemical Research · 年份：2018 · DOI：10.1021/acs.accounts.7b00573 · 被引用次数：364 · 研究领域：Carbohydrate Chemistry and Synthesis、Catalytic Alkyne Reactions、Synthetic Organic Chemistry Methods

Conspectus Naturally occurring glycans and glycoconjugates have extremely diverse structures and biological functions. Syntheses of these molecules and their artificial mimics, which have attracted the interest of those developing new therapeutic agents, rely on glycosylation methodologies to construct the various glycosidic linkages. In this regard, a wide array of glycosylation methods have been developed, and they mainly involve the substitution of a leaving group on the anomeric carbon of a glycosyl donor with an acceptor (a nucleophile) under the action of a particular promoter (usually a stoichiometric electrophile). However, glycosylations involving inherently unstable or unreactive donors/acceptors are still problematic. In those systems, reactions involving nucleophilic, electrophilic, or acidic species present on the leaving group and the promoter could become competitive and detrimental to the glycosylation. To address this problem, we applied the recently developed chemistry of alkynophilic gold(I) catalysts to the development of new glycosylation reactions that would avoid the use of the conventional leaving groups and promoters. Gratifyingly, glycosyl o -alkynylbenzoates (namely, glycosyl o -hexynyl- and o -cyclopropylethynylbenzoates) turned out to be privileged donors under gold(I) catalysis with Ph 3 PAuNTf 2 and Ph 3 PAuOTf. The merits of this new glycosylation protocol include the following: (1) the donors are easily prepared and are generally shelf-stable;...