Unexpected orthogonality of S-benzoxazolyl and S-thiazolinyl glycosides: application to expeditious oligosaccharide assembly.
Thorough mechanistic studies of the alkylation pathway for the activation of glycosyl thioimidates have led to the development of the "thioimidate-only orthogonal strategy". Discrimination among S-thiazolinyl (STaz) and S-benzoxazolyl (SBox) anomeric leaving groups was achieved by fine-tuning of the activation conditions. Preferential glycosidation of a certain thioimidate is not simply determined by the strength of activating reagents; instead, the type of activation--direct vs indirect--comes to the fore and plays the key role.
Kaeothip
Sophon
S
Department of Chemistry and Biochemistry, University of Missouri, St. Louis, One University Boulevard, St. Louis, Missouri 63121, USA.
Pornsuriyasak
Papapida
P
Rath
Nigam P
NP
Demchenko
Alexei V
AV
D000478:Alkylation; D000818:Animals; D001583:Benzoxazoles / Q000737:chemistry*; D006027:Glycosides / Q000737:chemistry*; D006031:Glycosylation; D007096:Imidoesters / Q000737:chemistry; D015394:Molecular Structure; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D013844:Thiazoles / Q000737:chemistry*
D001583:Benzoxazoles; D006027:Glycosides; D007096:Imidoesters; D009844:Oligosaccharides; D013844:Thiazoles