Water-Promoted Synthesis of Azepino3,4,5-cdindole Analogues via Pictet-Spengler Reaction

摘要

abstract_textpPictet-Spengler reaction is an important strategy for the chemical or biosynthetic construction of alkaloids. Various suitable catalysts have thus been developed to drive the reaction. We herein report for the first time that water could directly catalyze the Pictet-Spengler reactions of 2-(1H-indol-4-yl)ethanamines with aldehydes or ketones to generate azepino[3,4,5-cd]indoles. Notably, this protocol is environmentally benign and highly practical with a wide substrate scope and promising gram-scale applications. A plausible mechanism for this catalytic reaction is proposed to provide insights and potentially open a new avenue for organic synthesis./p/abstract_text