A New Biginelli Reaction Procedure Using Potassium Hydrogen Sulfate as the Promoter for an Efficient Synthesis of 3,4-Dihydropyrimidin-2(1H)-one - Tu, Shujiang; Fang, Fang; Zhu, Songlei; Li, Tuanjie; Zhang, Xiaojing; Zhuang, Qiya (Synlett, 2004)