<scp>Fe‐Catalyzed Pictet‐Spengler‐Type</scp> Cyclization <i>via</i> Selective <scp>Four‐Electron</scp> Reductive Functionalization of <scp>CO₂</scp>

Abstract

Main observation and conclusion Herein, we describe a novel catalytic Pictet‐Spengler‐type cyclization using CO 2 as a nontoxic and sustainable C1 feedstock with environmentally benign and non‐precious‐metal iron as catalyst. The reaction is achieved by selective four‐electron reduction of CO 2 into methylene level intermediate through carefully tuning the reaction parameters. A variety of tetrahydro‐β‐carbolines and other nitrogen‐containing heterocycles can be easily obtained under mild conditions. Mechanistic studies have shown that tetrahydro‐β‐carbolines are probably obtained via spiroindolenine intermediates.

Topics & Concepts