Three-component sequential synthesis of N,N′-disubstituted 5-arylidenedihydropyrimidine-2,4-dione
作者:Maria Cristina Bellucci、Alessandro Volonterio
DOI:10.1016/j.tetlet.2012.06.109
日期:2012.8
A three-component sequential process consisting in (1) in situ formation of carbodiimides by Staudinger reaction, (2) reaction with 2-(bromomethyl)-3-aryl-2-propenoicacids, and (3) final cyclization of the resulting N-acylurea intermediates in order to obtain the synthesis of an array of N,N′-disubstituted 5-arylidenedihydropyrimidine-2,4-dione under mild conditions is presented.
<i>N</i>-Phenyl-1,2,4-triazoline-3,5-dione (PTAD) as a Dienophilic Dinitrogen Equivalent: A Simple Synthesis of 3-Amino-1,2,4-benzotriazines from Arylcarbodiimides
N-Arylcarbodiimides react with PTAD to provide [1,2,4]triazolo[1,2-a][1,2,4]benzotriazines by a [4+2] cycloaddition reaction. When asymmetrically substituted diarylcarbodiimides are used, the cycloaddition proceeds with total chemoselectivity because only the more electron-rich aryl nucleus is involved. This observation has been rationalized by a computational study using DFT methods that shows that