New versatile Pd-catalyzed alkylation of indoles via nucleophilic allylic substitution: controlling the regioselectivity.
[reaction: see text] A systematic study addressed toward the optimization of the Pd-catalyzed alkylation of indoles by allylic carbonates is presented. The protocol uses a catalytic amount of [PdCl(pi-allyl)](2)/phosphine as a promoting agent, providing allylindoles in excellent yields. The regioselectivity of the reaction can be controlled by a proper choice of the base and the reaction media. The method proved to be effective also for intramolecular allylic alkylations of indolyl carbonates, providing a flexible route to fused indole alkaloids.
Bandini
Marco
M
Dipartimento di Chimica G. Ciamician, via Selmi 2, 40126, Bologna, Italy. marco.bandini@unibo.it
Melloni
Alfonso
A
Umani-Ronchi
Achille
A
D000478:Alkylation; D002254:Carbonates / Q000737:chemistry; D002384:Catalysis; D026121:Indole Alkaloids / Q000138:chemical synthesis*; D007211:Indoles / Q000032:analysis / Q000737:chemistry*; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*
D002254:Carbonates; D026121:Indole Alkaloids; D007211:Indoles; D010165:Palladium