Palladium-Catalyzed Proaromatic C(Alkenyl)-H Olefination: Synthesis of Densely Functionalized 1,3-Dienes

Org Lett. 2020 Sep 4;22(17):6765-6770. doi: 10.1021/acs.orglett.0c02241. Epub 2020 Aug 26.

Abstract

An example of proaromatic C(alkenyl)-H olefination is reported. This protocol utilized a free carboxylic acid as a directing group for C(alkenyl)-H activation of 1,4-cyclohexadiene and coupled with various alkenes. Direct and sequential bisolefinations of proaromatic acids were achieved. The synthetic applicability has been exhibited by [4 + 2] cycloaddition and decarboxylative aromatization of the resulting proaromatic 1,3-dienes. Additionally, several kinetic studies also have been carried out to elucidate the reaction mechanism.