Microwave-assisted reactions: Part 2Part 1: ref. 1. One-pot synthesis of pyrimido[1,2-a]pyrimidines

Abstract

A simple route for the synthesis of pyrimido[1,2-a]pyrimidines by condensation of 2-aminopyrimidine 1, aromatic aldehydes 2 and active methylene reagents 3 under microwave irradiation is reported.

Bicyclic 6 + 6 systems: the chemistry of pyrimido[4,5-d]pyrimidines and pyrimido[5,4-d]pyrimidines

“…23 Moreover, pyrimidopyrimidines are conveyed as receptors for tyrosine kinase 24 and have been applied in the biosynthesis of 5-phosphoribosyl-1-pyrophosphate. 25 Presently, the synthetic procedures of compounds that have a pyrimido [4,5-d]pyrimidine skeleton are variable using different routes, including: (1) the multicomponent condensation reaction of formaline with uracil analogs and amines which gives a product that has antidepressant activity; 22 and (2) several procedures including the three-component condensation of aryl aldehydes, amines such as aniline, aminouracil, thiocyanate salts or aminopyrimidine derivatives and active methylenes under catalytic conditions in a basic or acidic medium, [26][27][28][29][30][31][32][33][34][35][36][37][38] in addition to other reported synthetic approaches. 39,40 On the other hand, pyrimidopyrimidines were synthesized using a regiospecic one-pot reaction under solvent-free and microwave irradiation conditions.…”

Synthesis of New [1,2,4]Triazolo[1,5‐a]pyrimidine Derivatives: Reactivity of 3‐Amino[1,2,4]triazole towards Enaminonitriles and Enaminones

“…In continuation of our efforts aimed at developing new routes for the synthesis of polyfunctional substituted heterocycles , we report, herein, the results of our investigation for the reactivity of 3(5)‐amino‐[1,2,4]triazole with enaminonitriles and enaminones. A variety of new functionally 5‐substituted [1,2,4]triazolo[1,5‐ a ]pyrimidines and 6‐substituted [1,2,4]triazolo[1,5‐ a ]pyrimidines‐7‐amine was obtained in excellent yields.…”

Multicomponent reactions under increased pressure: on the reaction of arylhydrazonals, aromatic aldehydes and malononitrile in Q-Tube

“…We have also recently surveyed utility of multicomponent reactions in our area [2]. Since 1997, we investigated extensively utility of microwave to accelerate reaction rates [3][4][5][6]. As we became convinced that microwave techniques is very expensive to scale up and it is just allow reactions to proceed at higher temperature than that of the medium via formation of hot spots thus increasing the rate.…”

“…The reaction of arylhydrazonal (1j) with malononitrile and aromatic aldehydes afforded the corresponding biphenyl derivatives (4). However, compound 1h reacted with malononitrile and aromatic aldehydes (7) to afford pyridazino [5,4,3-de]1,6-naphthyridine-7-carbonitrile derivatives (8).…”