Polyethylene glycol(PEG) was found to be an effective catalyst for the condensation of 1,2-diamines with 1,2-dicarbonyl compounds to afford the corresponding quinoxaline derivatives in excellent yields under mild reaction conditions.
Zhang, Xia ZhongWang, Jin XianSun, Yong JunZhan, Hong Wen
A rapid and heterogeneous Pd/C-catalyzed atom-efficient phenylation of aryl bromides by sodium tetraphenylborate takes place under focused microwave irradiation in water. The palladium catalyst can be easily recovered and reused.
Fifteen dihydropyrimidinthiones have been synthesized by microwave-assisted Biginelli reactions without any solvent or catalyst. The advantages of this novel protocol include the excellent yield, operational simplicity, short time and the avoidance of the use of organic solvents and catalysts.
