Tandem aldol-Michael reactions in aqueous diethylamine medium: a greener and efficient approach to bis-pyrimidine derivatives.

A simple protocol, involving the green synthesis for the construction of novel bis-pyrimidine derivatives, 3a-i and 4a-e are accomplished by the aqueous diethylamine media promoted tandem Aldol-Michael reaction between two molecules of barbituric acid derivatives 1a,b with various aldehydes. This efficient synthetic protocol using an economic and environmentally friendly reaction media with versatility and shorter reaction time provides bis-pyrimidine derivatives with high yields (88%-99%).