One-Pot Synthesis of 2-Acetyl-1 H-pyrroles from N-Propargylic β-Enaminones via Intermediacy of 1,4-Oxazepines

J Org Chem. 2021 May 7;86(9):6289-6304. doi: 10.1021/acs.joc.1c00077. Epub 2021 Apr 19.

Abstract

A one-pot two-step protocol for the synthesis of 2-acetyl-1H-pyrroles from N-propargylic β-enaminones was described. When treated with zinc chloride in refluxing chloroform, N-propargylic β-enaminones produced in situ 2-methylene-2,3-dihydro-1,4-oxazepines, which, upon further refluxing in methanol with zinc chloride, afforded 2-acetyl-1H-pyrroles. The process was found to be general for a wide variety of N-propargylic β-enaminones and yielded a diverse range of 2-acetyl-1H-pyrroles in good to high yields with large substrate scope and good functional group tolerance. This operationally easy method may provide a rapid access to functionalized 2-acetyl-1H-pyrroles of pharmacological interest.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Oxazepines*
  • Pyrroles*

Substances

  • Oxazepines
  • Pyrroles