EPC synthesis of 6-substituted 2-oxo-cyclohexanecarboxylates via conjugate addition of cuprates to asymmetric shielded 2-oxo-cyclohexenecarboxylates

Abstract

Asymmetric shielded 2-oxo-cyclohexenecarboxylates 6n and 6x were prepared by transesterification of 2-oxo-cyclohexanecarboxylate 2 with camphor derived concave alcohols 1n and 1x and by subsequent introduction of a double bond via phenylselenides. Diastereoselective conjugate addition of equimolar amounts of mixed cuprates at −78 °C and deprotection by methanolysis gave enantiomerically pure 6-substituted 2-oxo-cyclohexanecarboxylates 14–19 and ent-14–19, valuable as chiral building blocks in natural product synthesis.