Regio- and Diastereoselective Decarboxylative Coupling of Heteroaromatic Alkanes

Allylic esters of heteroaromatic alkanes undergo facile palladium-catalyzed decarboxylative coupling. The resulting C−C bond is formed with high diastereoselectivity and high regioselectivity for coupling at the more substituted allyl terminus. It is proposed that this unusual combination of selectivities results from a tandem allylation/aza-Cope rearrangement sequence. After allylation, decarboxylative dearomatization produces an intermediate for the aza-Cope rearrangement. The subsequent aza-Cope rearrangement occurs under mild conditions because it is driven by rearomatization.