| |
[摘要]：A simple two-step procedure yielding gamma-azido-beta-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 alpha-functionalized ketones. The azido ketones or their cyclic isomers are transformed into ureido-substituted Delta(1)- or/and Delta(2)-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 gamma-azido-beta-ureido ketones have been also developed. |
|
