Trichloroisocyanuric acid (TCCA): A Suitable Reagent for Direct Glycosylations of C1‐Hemiacetals with Different Nucleophiles

Abstract Trichloroisocyanuric acid (TCCA), a readily accessible, inexpensive, shelf‐stable, and non‐toxic reagent in combination with PPh 3 , has been used for dehydrative glycosylation reactions with furanose, pyranose, and deoxy‐sugar hemiacetals. The methodology provides a mild reaction condition, good functional group tolerance, featuring a wide variety of substrate scope using O ‐, C ‐, N ‐, and S ‐based nucleophiles with good to excellent yields and majority α‐selectivity in case of O ‐glycosides while the stereoselectivity in case of C ‐, N ‐ and S ‐ glycosides depends upon the nature of nucleophiles. Notably, this mild dehydrative glycosylation system also provides a reliable method for the synthesis of challenging phenolic glycosides. The progress of the dehydrative glycosylation reaction was monitored by mass and NMR spectroscopy and it is hypothesized that alkoxyphosphonium ions might be the reactive intermediate formed in this process, supported by 31 P nuclear magnetic resonance studies.