Extending the S-benzimidazolyl (SBiz) platform: N-alkylated SBiz glycosyl donors with the universal activation profile

This article describes the development of alkylated S-benzimidazolyl (SBiz) imidates as versatile building blocks for chemical glycosylation. The SBiz imidates have been originally developed as a new platform for active-latent glycosylations and its utility was further extended to other common strategies for oligosaccharide synthesis. This article expands upon the utility of these compounds. We developed a general protocol for the synthesis of a series of N-alkylated SBiz glycosides from N-protected SBiz aglycones by Lewis acid-mediated coupling with glucose pentaacetate. The N-alkylated SBiz moiety was found to be stable under strong basic conditions which allowed us to obtain both armed and disarmed N-alkylated SBiz donors. These donors showed good reactivity at a variety of activation conditions, and generally provided high yields in glycosylations.