A self-intermolecular cyclocondensation reaction of 3,4-dihydropyrimidine-2-thione（DHPM） to give a novel tricyclic structure containing DHPM core in the presence of diethyl azodicarboxylate（DEAD） and triphenylphosphine（TPP） at room temperature is reported.
A highly efficient synthesis of novel pyrido[2,3-d]pyrimidin-4-ols was developed via an iodine-catalyzed tandem oxidative cyclization under focused microwave irradiation. Pyrido[2,3-d]pyrimidin-4-ols were obtained from easily available 2-amino-4-aryl-6-arylnicotinamides and benzylic amines with good to excellent yields.
