Acid-catalyzed rearrangement of 1-acyl-2-azabuta-1,3-dienes to 4-pyrrolin-2-ones
作者:Nikolai V. Rostovskii、Ilia A. Smetanin、Alexander N. Koronatov、Anastasiya V. Agafonova、Vasilii V. Potapenkov、Alexander F. Khlebnikov、Mikhail S. Novikov
DOI:10.1007/s10593-020-02745-x
日期:2020.7
1-acetyl-2-azabuta-1,3-dienes were stable toward rearrangement, while brominated analogs rearranged into 4-pyrrolin-2-ones, probably as a result of the initial radical hydrodebromination. According to calculations performed at the DFT level, two steps of the reaction were catalyzed by acid: the cyclization of 2-azabutadiene and the sigmatropic shift in the 2-hydroxy-2Н-pyrrole intermediate.
K<sub>2</sub>S<sub>2</sub>O<sub>8</sub>/TEMPO-Induced Cascade Oxidative Cyclization/1,2-Migration of Electron-Deficient Groups: Strategy for the Construction of 1<i>H</i>-Pyrrol-2(3<i>H</i>)-ones
A K2S2O8/TEMPO-induced oxidative cyclization of N-unprotected enaminoesters and enaminones that gave 1H-pyrrol-2(3H)-ones in good yields with broad functional group compatibility is reported. This method provides easy access to 1,2-carbon migration of ester or acyl group under transition-metal-free conditions.
MOON M. W., J. ORG. CHEM. <JOCE-AH>, 1977, 42, NO 13, 2219-2223