Gold-catalyzed methodologies in carbohydrate syntheses

Abstract

The chemistry of gold has been exploited often for the anomeric center for a variety of glycosidations though initial studies were devoted to the oxidation of alkynes and polyols. Excellent alkynophilicity coupled with the availability of gold complexes has led to the development of practical, versatile, mild, and catalytic glycosidation methods. A variety of functional groups at the anomeric center were activated including propargyloxy, 1,2-orthoesters, esters containing alkynes, thioglycosides with alkynes, carbonates bearing alkynes, etc. Efforts are also devoted to use the Lewis acidity and Brønsted acidity of gold complexes for activating the anomeric center. Emergence of gold-catalyzed glycosidation methods has significantly contributed to the syntheses of oligosaccharides during the past 5 years. The coming years and decades will see more efforts than ever in improving the catalytic turnover numbers for producing pharmaceutically relevant and therapeutically important carbohydrate-based drugs and vaccine candidates.