Synthesis of γ-azido-β-ureido ketones and their transformation into functionalized pyrrolines and pyrroles via Staudinger/aza-Wittig reaction

J Org Chem. 2013 Feb 1;78(3):1190-207. doi: 10.1021/jo302724y. Epub 2013 Jan 10.

Abstract

A simple two-step procedure yielding γ-azido-β-ureido ketones or/and their cyclic isomers, 6-(1-azidoalkyl)-4-hydroxyhexahydropyrimidin-2-ones, has been developed. The synthesis includes three-component condensation of acetals of 2-azidoaldehydes with urea or methylurea and p-toluenesulfinic acid in aqueous formic acid followed by reaction of the obtained N-[(2-azido-1-tosyl)alkyl]ureas with sodium enolates of α-functionalized ketones. The azido ketones or their cyclic isomers are transformed into ureido-substituted Δ(1)- or/and Δ(2)-pyrrolines via Staudinger/aza-Wittig reaction promoted by PPh(3). The obtained pyrrolines are converted into 3-functionalized 1H-pyrroles via elimination of urea under acidic conditions. Convenient one-pot syntheses of 1H-pyrroles starting from N-[(2-azido-1-tosyl)alkyl]ureas or γ-azido-β-ureido ketones have been also developed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Azides / chemical synthesis*
  • Azides / chemistry
  • Carboxylic Acids / chemistry
  • Ketones / chemical synthesis*
  • Ketones / chemistry
  • Molecular Structure
  • Pyrroles / chemical synthesis*
  • Pyrroles / chemistry
  • Urea / analogs & derivatives*
  • Urea / chemical synthesis*
  • Urea / chemistry

Substances

  • Azides
  • Carboxylic Acids
  • Ketones
  • Pyrroles
  • Urea