Efficient protocol for the production of pyrimido[4,5-b] quinolines using an organic-inorganic hybrid catalyst

In this work, an efficient protocol for the synthesis of pyrimido[4,5-b]quinolines was reported. The one-pot multi-component reaction of arylaldehydes, barbituric acid (or 2-thiobarbituric acid) and anilines in the presence of an organic-inorganic hybrid material namely tetramethyl-N-(silica-n-propyl)-N′-sulfonic acid-ethylenediaminium chloride/mesylate ([TSSECM]) afforded the mentioned compounds. This protocol has several advantages including, high yields (86-95%), relatively short reaction times (110-120 min), recyclability of the catalyst and easy purification of the products without column chromatography.