Dual-regioselective direct C(sp2)-arylation of unprotected β-enamino esters with 2-indolylmethanols catalyzed by Brønsted acid

Abstract

An efficient dual-regioselective strategy has been developed for the direct C(sp²)-arylation of β-enamino esters with 2-indolylmethanols, employing diphenyl phosphate as the catalyst without the need for amino group protection. 48 structurally diverse indole-enamino ester hybrids were synthesized in moderate to excellent yields (up to 98%). Notably, this approach effectively suppresses the competitive N-arylation byproduct formation commonly encountered in traditional approaches and represents the successful precise integration of β-enamino esters and indoles, offering a modular and efficient route to complex heterocyclic architectures with potential bioactivities.