Manipulation of N,O-Nucleophilicity: Efficient Formation of 4-N-Substituted 2,4-Dihydro-3<i>H</i>-1,2,4-Triazolin-3-ones
作者:Xianhai Huang、Anandan Palani、Dong Xiao、Robert Aslanian、Neng-Yang Shih
DOI:10.1021/ol0478638
日期:2004.12.1
A new efficient two-step synthesis of 2,4-dihydro-3H-1,2,4-triazolin-3-ones (triazolinones) from readily available amines is reported. Our novel conditions using hexamethyl disilazane, bromotrimethylsilane, and a catalytic amount of ammonium sulfate smoothly cyclize 1-formyl and 1-acetyl semicarbazides to the target triazolinones. This transformation features simultaneous manipulation of N- and O-nucleophilicity as well as differentiation of the nucleophilicity of a urea and an acyl carbonyl.