Base‐ and Radical‐Mediated Regio‐ and Stereoselective Additions of Thiols, Thio‐Sugars, and Thiol‐Containing Peptides to Trisubstituted Activated exo‐Glycals

Abstract

AbstractA study was performed for the coupling of thiols, thio‐sugars, and thiol‐containing amino acids and peptides with trisubstituted activated anomeric sugar olefins under basic and radical conditions. The hydrothiolation reaction took place in a regio‐ and stereospecific manner and occurred at the anomeric center and mainly from an approach to the less crowded face, that is, opposite to the O‐4 protecting group. Furano‐ and pyranoglycosylidenes were valuable substrates for the base‐mediated coupling with aromatic and primary thiols, which included 6‐thio‐sugars, cysteine derivatives, and glutathione. The success of the radical‐mediated method depended on the thiol partners as well as the nature of the sugar olefins. Neither of the conditions required the protection of the sugar or the cysteine derivatives.