A pentacarbomethoxycyclopentadiene (PCCP) organic Brønsted acid catalyzed stereoselective glycosidation of N-pentenyl orthoesters (NPOE) of d-glucose and d-galactose, in conjunction with N-iodosuccinimide.

Herein, we report our preliminary results in utilizing the organic Brønsted acid, pentacarbomethoxycyclopentadiene (PCCP), for catalysing the glycosidation with n-pentenyl orthoesters (NPOE) of d-glucose and d-galactose in the presence of N-iodosuccinimide (NIS). Benzoyl and benzyl protection in d-glucosyl NPOEs led to 1,2-trans glycosides, while acetyl protection in NPOE led to a mixture of 1,2-cis and trans glycosides with >75% cis selectivity, and d-galactosyl NPOEs led to 1,2-orthoesters. Substrate scope was demonstrated with acceptors of natural product relevance. This article highlights the prospect of utilizing the organic Brønsted acid, PCCP, for stereoselective glycosidation.