Conjugate addition of 2- and 4-pyridylcuprates: an expeditious asymmetric synthesis of natural (-)-evoninic acid.

Alan C Spivey, Lena Shukla, Judy F Hayler

Index: Org. Lett. 9 , 891, (2007)

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Abstract

[reaction: see text] The scope and limitations of the conjugate addition of 2- and the first 4-pyridyl Gilman homocuprates to various alpha,beta-unsaturated Michael acceptors are delineated. The conjugate addition of the cuprate of 2-bromo-3-methylpyridine to (E)-methyl crotonate then diastereoselective enolate alkylation and lipase-mediated enantioselective ester hydrolysis have enabled an efficient four-step first asymmetric synthesis of the Celastraceae sesquiterpenoid esterifying ligand (-)-(1'S,2'S)-evoninic acid.