KI-Catalyzed Oxidative Cyclization of Enamines and tBuONO to Access Functional Imidazole-4-Carboxylic Derivatives.

A simple protocol for the noble-metal-free oxidative cyclization of enamines and tBuONO has been developed. This KI-mediated formal [4 + 1] cycloamination reaction provides a practical strategy for the synthesis of imidazole-4-carboxylic derivatives using tBuONO both as an aminating reagent and oxidant. The reaction features wide substrate scope and good functional tolerance for enamine compounds, even the unactivated ones.

IBX-Promoted Oxidative Cyclization of N-Hydroxyalkyl Enamines: A Metal-Free Approach toward 2,3-Disubstituted Pyrroles and Pyridines.

An iodoxybenzoic acid-mediated selected oxidative cyclization of N-hydroxyalkyl enamines was developed. Through this strategy, a variety of 2,3-disubstituted pyrroles and pyridines were produced in good selectivity involving oxidation of alcohol, followed by condensation of aldehyde and α-C of enamines. Furthermore, this metal-free method has several advantages, including the use of environmentally friendly reagents, broad substrate scope, mild reaction conditions, and high efficiency.