Asymmetric synthesis of hexapropionate synthons by sequential enantiotopic group selective enolization of meso
Dale E Ward1, H Martin Gillis, Olukayode T Akinnusi
1Department of Chemistry, University of Saskatchewan, Saskatoon, SK S7N 5C9, Canada. dale.ward@usask.ca
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]
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