Gold(I)-Catalyzed Glycosylation with Glycosyl Ynenoates as Donors

A simple and versatile glycosylation method with both armed and disarmed glycosyl ynenoates as donors is developed. Employing a gold(I) complex as catalyst with or without the assistance of TfOH, the scope of the present glycosylation protocol is very wide. The utility of the present ynenoate donors is demonstrated in the efficient synthesis of oligosaccharides via the latent-active strategy and the multiple orthogonal one-pot strategy. Finally, this approach enables the formal synthesis of the tetrasaccharide hapten of Streptococcus pneumoniae serotype 3 and the highly convergent synthesis of the 32mer polymannoside.