Microwave assisted synthesis of pyrimido[4,5-d]pyrimidine derivatives in dry media

Pyrimido[4,5-d]pyrimidine derivatives were synthesized by using an efficient, facile and solvent-free procedure. Here, a non-conventional synthetic procedure has been developed where solid support of alumina is used as energy transfer medium under microwave irradiation (MWI) which devoids hazards of solution phase reactions. The reaction time has been brought down from minutes to seconds with improved yield as compared to reported method.Похідні піримідо[4,5-d]піримідину синтезовано за допомогою простого й ефективного методу без застосування розчинника. Розроблено нетрадиційний спосіб синтезу, за якого нерухому підкладку із оксиду алюмінію використано як середовище для передачі енергії при мікрохвильовому випромінюванні, що запобігає негативним ефектам, які обумовлюють реакції у фазі розчинника. Новий метод дає змогу скоротити час реакції від декількох хвилин до кількох секунд і покращити її вихід

A Study on the Rearrangement of Dialkyl 1-Aryl-1-hydroxymethylphosphonates to Benzyl Phosphates

The phospha-Brook rearrangement of dialkyl 1-aryl-1-hydroxymethylphosphonates (HPs) to the corresponding benzyl phosphates (BPs) has been elaborated under solid–liquid phase transfer catalytic conditions. The best procedure involved the use of triethylbenzylammonium chloride as the catalyst and Cs2CO3 as the base in acetonitrile as the solvent at room temperature. The substrate dependence of the rearrangement has been studied, and the mechanism of the transformation under discussion was explored by quantum chemical calculations. The key intermediate is an oxaphosphirane. The one-pot version starting with the Pudovik reaction has also been developed. The conditions of this tandem transformation were the same, as those for the one-step HP→BP conversion