A redox-neutral weak carbonyl chelation assisted C4–H allylation of indoles with vinylcyclopropanes

Abstract

Removable chelating group-assisted Ru-catalyzed distal C4–H allylation of indoles has been accomplished using vinylcyclopropanes as the allylating agent with broad substrate scope.

Palladium Catalysis Enabled Sequential C(sp3)–H/C–C Activation: Access to Vinyl γ-Lactams

“…In this vein, the readily accessible three-membered vinylcyclopropanes (VCPs) can be used as versatile coupling partners from a step and atom economy standpoint . However, the previous studies on VCP in C–H functionalization are mainly restricted to aromatic C­(sp 2 )–H allylation followed by ring opening via C–C cleavage under transition-metal catalysis (Scheme a). , This could be due to the low reactivity of the metal–C­(alkyl) substrate and the high reactivity of the strained ring that may lead to decomposition or uncontrolled reactions . Despite these synthetic challenges, the reactivity of VCP in the C­(sp 3 )–H functionalization would be valuable.…”

“…Based on mechanistic studies and literature reports, , the ligand exchange with Pd­(OAc) 2 can generate the active palladium species, which activates the β-C­(sp 3 )–H bond of substrate 1a and gives the five-membered palladium intermediate A (Scheme S4, SI). Coordination of VCP followed by 1,2-migratory insertion can lead to the formation of B , which may preferentially undergo direct β-hydride elimination rather than β-carbon elimination, resulting in the formation of C .…”