Microwave-assisted regioselective olefinations of cyclic mono- and di-ketones with a stabilized phosphorus ylide
作者:Jinlong Wu、Dan Li、Huafeng Wu、Lijie Sun、Wei-Min Dai
DOI:10.1016/j.tet.2005.12.060
日期:2006.5
4-cyclohexanediones with the ylide at 190 °C for 20 min in MeCN afforded the exocyclicolefins in >94:6 isomer ratios. On the other hand, the same reactions carried out at 230 °C for 20 min in the presence of 20 mol % DBU furnished the endocyclicolefins in >83:17 isomer ratios. The base-mediated isomerization of the exocyclicolefins into the endocyclic isomers was primarily driven by thermodynamic stability of the