Oxidative activation of C-S bonds with an electropositive nitrogen promoter enables orthogonal glycosylation of alkyl over phenyl thioglycosides

Identifier:  imarina:6040629

Handle: https://hdl.handle.net/20.500.11797/imarina6040629

Authors:  Kitowski, A; Jiménez-Moreno, E; Salvadó, M; Mestre, J; Castillón, S; Jiménez-Osés, G; Boutureira, O; Bemardes, GJL

Abstract:
© 2017 American Chemical Society. A method for the selective activation of thioglycosides that uses the N+-thiophilic reagent Omesitylenesulfonylhydroxylamine (MSH) as a promoter is presented. The reaction proceeds via anomeric mesitylensulfonate intermediates, which could be isolated and fully characterized by placing a fluorine atom at the C2 position. In the presence of a soft Lewis acid, glycosylation reaction proceeds at ambient temperature with good yields. It is further demonstrated that it is possible to orthogonally activate S-ethyl in the presence of S-phenyl donors, enabling the design of sequential glycosylation strategies.