Cu-Catalyzed Cascade Cyclization of Ketoxime Acetates and Alkynals Enabling Synthesis of Acylpyrroles

Main observation and conclusion A facile copper-based catalytic system has been developed to enable efficient cyclization of methylketoximes and alkynals. This protocol provides a viable entry to synthetically and pharmaceutically useful 2-acylpyrroles with a broad range of compatible functionalities. Mechanistically, a key acyl migration is probably involved that leads to the formation of N-acyl pyrroles or otherwise NH pyrroles by further hydrolysis. More importantly, the present reaction system also gives an opportunity to realize three-component pyrrole assembly by simple addition of carboxylic acid. [GRAPHICS] .

Automated summary

This study introduces a copper-based catalytic system for the efficient cyclization of methylketoximes and alkynals, offering a viable approach to synthesize 2-acylpyrroles with a broad range of compatible functionalities. Additionally, it suggests a key acyl migration mechanism that leads to the formation of N-acyl pyrroles or NH pyrroles by further hydrolysis, and also provides an opportunity for a three-component pyrrole assembly by simple addition of carboxylic acid.