β-Carboline Amides as Intrinsic Directing Groups for C(sp2)-H Functionalization

Many site-selective palladium-catalyzed C-H functionalization methods require directing groups. We report here beta-carboline amides as intrinsic directing groups for C(sp(2))-H functionalization. Various substrates including the natural product alangiobussinine and the marinacarboline core structure were functionalized using carboline-directed delta-C(sp(2))-H alkynylations. This transformation proceeds under mild conditions and is compatible with a wide variety of beta-arylethamines. delta-Alkynylation of beta-arylethamines via a six-membered palladacycle is favored over gamma-C(sp(2))-H bond functionalization when both positions are accessible. The versatility of beta-carboline amides as directing groups is evidenced by other delta-C(sp(2))-H functionalizations such as alkenylation, arylation, and C-N bond formation.