Synthesis of oligosaccharides using per-O-trimethylsilyl-glycosyl iodides as glycosyl donor

•Oligosaccharide synthesis using simultaneously TMS-protected donor and acceptor.•Cheap, commercially available triethylamine used as a promoter.•Glycosylation with exclusive α-stereoselectivity and good yields achieved. Trimethylsilyl (TMS) protecting group has been found to be very useful for the simultaneous protection of both the glycosyl donor- and the acceptor-substrates in oligosaccharide synthesis. Thus, while the per-O-trimethylsilylated glycosyl iodides served as the glycosyl donor, those bearing selectively exposed primary hydroxyl groups were found suitable as the glycosyl acceptor for the reaction. The cheap and commercially available trialkylamine, triethylamine was found to be an effective promoter for the glycosylation. Importantly, the reaction was α-stereospecific and gave the products in 58%–78% yields. [Display omitted]