Brønsted Acid Catalyzed (4 + 2) Cyclocondensation of 3-Substituted Indoles with Donor–Acceptor Cyclopropanes
Alesandere Ortega, Uxue Uria, Tomás Tejero, Liher Prieto, Efraím Reyes, Pedro Merino, José L. Vicário
Abstract
Acylcyclopropanes are employed as useful donor–acceptor cyclopropanes that undergo formal (4 + 2) cyclocondensation with N-unprotected 3-substituted indoles in the presence of a Brønsted acid catalyst. The reaction involves the simultaneous alkylation of both the N and C-2 positions of the indole and provides access to the 8,9-dihydropyrido[1,2-a]indole scaffold that is the central core of several biologically relevant indole alkaloids in excellent yields and good selectivities.
Topics & Concepts
ChemistryCatalysisBrønsted–Lowry acid–base theoryAcceptorCombinatorial chemistryOrganic chemistryMedicinal chemistryStereochemistryPhysicsCondensed matter physicsCyclopropane Reaction MechanismsCatalytic Alkyne ReactionsAsymmetric Synthesis and Catalysis