Intramolecular Friedel-Crafts alkylation with a silylium-ion-activated cyclopropyl group: formation of tricyclic ring systems from benzyl-substituted vinylcyclopropanes and hydrosilanes.

ABSTRACT: A trityl-cation-initiated annulation of benzyl-substituted vinylcyclopropanes (VCPs) with hydrosilanes is reported. Two Si-C(sp³) bonds and one C(sp²)-C(sp³) bond are formed in this process where an intramolecular 6-endo-tet Friedel-Crafts alkylation of a silylium-ion-activated cyclopropane ring is the rate-determining key step. The reaction mechanism is proposed based on computations and is in agreement with experimental observations. The new reaction leads to an unprecedented silicon-containing 6/6/5-fused ring system. A phenethyl-substituted VCP derivative yields another unknown tricycle having 6/6/6 ring fusion by reacting in a related but different way involving a 6-exo-tet ring closure.

SUBMITTER: He T 

PROVIDER: S-EPMC8178999 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature