Organic Letters 2006-06-08

Asymmetric synthesis of hexapropionate synthons by sequential enantiotopic group selective enolization of meso diketones.

Dale E Ward, H Martin Gillis, Olukayode T Akinnusi, M Abdul Rasheed, K Saravanan, Pradip K Sasmal

Index: Org. Lett. 8(12) , 2631-4, (2006)

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Abstract

Meso 1,9-diketones (six to seven stereocenters) are readily obtained by stepwise or simultaneous two-directional aldol reactions of tetrahydro-4H-thiopyran-4-one with a thiopyran-derived aldehyde or dialdehyde. Enantioselective enolizations of these diketones with the lithium amide from (R,R)-bis(1-phenylethyl)amine occur with simultaneous kinetic resolution to give the mono-TMS enol ethers in >90% yields (BORSM) and >95% ee. The products are applicable to polypropionate synthesis. [reaction: see text]