A short entry to novel C(2)-methyl branched 4a-carbafuranoses

A concise, diastereoselective synthesis of 2-C-methyl-4a-carba-?-d-lyxofuranose 13 and 2-C-methyl-4a-carba-?-d-arabinofuranose 14, two novel representatives of the branched-chain carbasugar family, is presented. The construction is based on the sequential execution of two strategic carbon-carbon bond-forming reactions, a vinylogous crossed aldol addition (1+2->3), and a rare silylative cycloaldolization (8->9+10).