Stereocontrol of All-Carbon Quaternary Centers through Enantioselective Desymmetrization of Meso Primary Diols by Organocatalyzed Acyl Transfer

The symmetry breaking of meso primary diols bearing a tetrahydropyran ring was employed, using catalytic asymmetric acyl transfer, to control all-carbon quaternary stereocenters. The planar chiral Fu DMAP catalyst was used in this reaction to reach a high degree of enantioselectivity (up to 97:3 e.r.) through a synergic effect combining a desymmetrization step and a kinetic resolution. Moreover, a beneficial effect was exhibited by C6F6 solvent, yielding the first example of an organocatalyzed asymmetric acyl transfer. The desymmetrized monoesters were then used to obtain, after a straightforward ring opening sequence, complex polyketide building blocks bearing all-carbon quaternary stereocenters.