2β,3β-difluorosialic acid derivatives structurally modified at the C-4 position:: synthesis and biological evaluation as inhibitors of human parainfluenza virus type 1

A series of 4-O-substituted 2beta,3beta-difluorosialic acid derivatives (3a-d) has been synthesized. A key intermediate was synthesized efficiently by the electrophilic syn-addition of fluorine to the double bond of a glycal precursor using molecular fluorine or xenon difluoride in the presence of BF3.OEt2. Among compounds 3a-d, the 4-O-thiocarbamoylmethyl derivative 3c showed the most potent inhibitory activity against sialidase of human parainflueriza virus type 1. 4-O-substituted analogues of 2beta,3beta-difluorosialic acid [GRAPHICS] (C) 2004 Elsevier Ltd. All rights reserved.