Value-added carbohydrate building blocks by regioselective O-alkylation of C-glucosyl compounds

Functionalized carbohydrates and especially functionalized C-glycosides are useful intermediates for the synthesis of complex carbohydrates of interest. In this paper, we describe the synthesis of C-azidopropylglucopyranosides and give a full account of their regioselective acylation and alkylation. Alkylation of these C-glucosyl compounds containing 1,2-trans-diol, namely 2- and 3-OH were first optimized with benzyl bromide. The reaction has then been extended to various electrophiles thus providing 3-O-substituted C-glucosyl compounds. These results are one of the first examples of regioselective alkylation with functionalized electrophiles on glycosyl compounds featuring a trans-vicinal diol. Furthermore, we describe some results obtained during regioselective deprotection of 4,6-O-benzylidene protecting group. This work opens the way to the synthesis of complex carbohydrate derivatives.