β‐Selective Glycosylation by Using O‐Aryl‐Protected Glycosyl Donors

Abstract

New glycosyl donors have been developed that contained several para-substituted O-aryl protecting groups and their stereoselectivity for the glycosylation reactionw as evaluated. Ah ighly b-selective glycosylationr eactionw as achieved by using thioglycosides that were protected by 4nitrophenyl (NP) groups, which were introduced by using the corresponding diaryliodonium triflate. Analysis of the stereoselectivities of several glycosyld onors indicated that the b-glycosides were obtained through an S N 2-type displacementf rom the corresponding a-glycosyl triflate. The NP group could be removed by reduction of the nitro group and acylation, followed by oxidation with cerica mmonium nitrate (CAN).

Stereoselective AromaticO-Glycosylation of Glycosyl Chloride with Arylboronic Acid under an Air Atmosphere

“…For example, arbutin, a simple aromatic O -glycoside, is used in the treatment of hyperpigmentation, and vancomycin, a more complex aromatic O -glycoside, is a broad-spectrum antibiotic (Figure ). In addition to the important medicinal applications of naturally occurring O -aryl glycosides, synthetic derivatives have also found broad utility in chemical synthesis, such as protecting groups or leaving groups in glycosylation reactions . Furthermore, β- O -aryl glycosides have been found to have various biological activities and pharmaceutical potentials in antitumor, anti-HIV, and antibacterial applications .…”