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 Δ1- or/and Δ2-pyrrolines via Staudinger/aza-Wittig reaction promoted by PPh3. 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.
Supporting Information
Copies of 1H and 13C NMR and IR spectra of all the synthesized compounds; 1H,1H-NOESY of trans-15e; 1H NMR spectra of the reaction mixtures formed from 12a,j,13b,m,r and PPh3. This material is available free of charge via the Internet at http://pubs.acs.org.
