Asymmetric conjugate 1,6-addition of organocuprates to N-dienoyl oxazolidinones

Abstract

A highly regioselective and diastereoselective conjugate 1,6-addition of organocuprates to N-dienoyl oxazolidinones to provide the 1,6-addition products, is described. These products have a β,γ-unsaturated olefin and a new asymmetric center at C(δ). The 1,6-addition products were obtained as a mixture of geometric isomers (E,Z), where its prevalence depends on reaction conditions and the type of Grignard reagent. This methodology can be carried out with small or voluminous alkyl Grignard reagents, aromatic or vinylic Grignard reagents, unlike other methodologies where there are difficulties with bulky Grignard reagents. It is the first paper describing a competition between geometric isomers (E, Z) into the 1,6- addition products depending on the employed reaction conditions. Chiral oxazolidinone moiety removal furnished chiral δ-substituted β,γ-unsaturated carboxylic acids.