The 2-(2-chloroacetoxyethyl)benzoyl group — stable to hydrogenolysis and cleavable beside other acyl groups

Abstract

The 2-(2-chloroacetoxyethyl)benzoyl (CAEB) group is prepared from isochromane in 4 steps and used as a temporary protecting group for carbohydrates. The CAEB group functions as a neighboring active, 1,2- trans -directing blocking group for glycosyl donors. It does not show transesterification to less reactive nucleophiles and is stable toward hydrogenolysis. CAEB can be cleaved off with thiourea and without effecting other acyl groups. It is suited for orthogonal protection strategies in combination with acetyl, benzoyl, benzyl and benzylidene groups in saccharide synthesis. The 2-(2-chloroacetoxyethyl)benzoyl (CAEB) group is used as a hydrogenolytically stable protecting group for carbohydrates. It behaves as a 1,2- trans -directing temporary blocking of position 2 in glycosyl donors and can be cleaved without affecting other acyl groups.