<i>S</i>-Benzoxazolyl as a Stable Protecting Moiety and a Potent Anomeric Leaving Group in Oligosaccharide Synthesis
作者:Medha N. Kamat、Cristina De Meo、Alexei V. Demchenko
DOI:10.1021/jo071191s
日期:2007.8.31
As a part of a program for developing new versatile building blocks for stereoselective glycosylation and convergent oligosaccharide synthesis, we demonstrated that S-benzoxazolyl (SBox) glycosides are stable toward major protecting group manipulations employed in carbohydrate chemistry. On the other hand, they can be glycosidated under relatively mild reaction conditions to afford either 1,2-trans
Glycosyl thioimidates in a highly convergent one-pot strategy for oligosaccharide synthesis
作者:Papapida Pornsuriyasak、Alexei V. Demchenko
DOI:10.1016/j.tetasy.2004.11.029
日期:2005.1
Application of two classes of thioimidoyl derivatives, S-benzoxazolyl (SBox) and S-thiazolyl (STaz) glycosides to selective activation over thioglycosides is described. These results allowed us to synthesize a tetrasaccharide derivative using a leaving group differentiated one-pot strategy in 73% yield over three sequential glycosylation steps. (C) 2004 Elsevier Ltd. All rights reserved.
On Orthogonal and Selective Activation of Glycosyl Thioimidates and Thioglycosides: Application to Oligosaccharide Assembly
作者:Sophon Kaeothip、Alexei V. Demchenko
DOI:10.1021/jo201117s
日期:2011.9.16
Discrimination among S-thiazolinyl (STaz), S-benzoxazolyl (SBox), and S-ethyl anomeric leaving groups was achieved by fine-tuning activation conditions. Preferential glycosidation of a certain leaving group is determined neither by the strength of the activating reagent nor by the stability of the leaving group itself; instead, the type of activation plays the key role. The activation conditions established herein were applied to a sequential five-step synthesis of a hexasaccharide using six monosaccharide building blocks equipped with six different leaving groups.