The First Highly Efficient Asymmetric Synthesis of α-Substituted Methyl Sulfonates

The right choice of sugar auxiliary led to a breakthrough in the first asymmetric α-alkylations of sulfonic acid esters (see scheme). The high asymmetric inductions were reached with 1,2:5,6-di-O-isopropyliden-α-D-allofuranose as the auxiliary group, which can be cleaved off again under mild conditions. Enantiopure α-substituted methyl sulfonates are important building blocks and precursors of bioactive compounds.