Convenient Synthesis of Dihydropyridine and Dihydropyrimidinethione Derivatives Using a Porphyrin Cored G1 PAMAM Dendrimer as a Homogeneous Catalyst

Abstract

AbstractPorphyrin cored poly(amidoamine) (G1 POR‐PAMAM) dendrimer based simple, mild, and selective homogeneous base catalyst was successfully synthesized. It was characterized by different spectral studies including UV‐Vis, FT‐IR, 1H NMR and 13C NMR. The G1 POR‐PAMAM was a very selective and efficient organocatalyst capable of promoting chemical reactions in an environment friendly way with high efficiency. The product selective property of G1 POR‐PAMAM was mainly studied in Biginelli andHantzschpyridine synthesis reactions. The G1 POR‐PAMAM catalyst was acting as a chemical switch for the selective synthesis of pyridine and pyrimidine derivatives exclusively. It was a convenient, green and efficient procedure for the exclusive synthesis of 1,4‐dihydropyridine, or 3,4‐ dihydropyrimidin‐2(1H)‐thione derivatives using the three‐component coupling reaction of aldehydes, ethylacetoacetate and ammonium thiocyanate. A variety of these compounds were produced in single step by the use of different starting materials. Within 45 minutes, the products were obtained with high yield (92‐99%). The catalyst could be reused upto six reaction cycles without significant loss of its catalytic activity.