SYNTHESIS OF NEW PYRIDO[2,3-d]PYRIMIDIN-5-ONES AND PYRIDO[2,3-d]PYRIMIDIN-7-ONES FUNCTIONALIZED AT POSITION 4 FROM 5-ACETYL-6-AMINO-4-METHYLSULFANYL-2-PHENYLPYRIMIDINE

Abstract

Methods were developed for the synthesis of new pyrido[2,3-d]pyrimidin-5-ones and pyrido[2,3-d]pyrimidin-7-ones from 5-acetyl-N-acyl-6-amino-4-methylsulfanyl-2-phenylpyrimidines. Heating the latter with MeONa at reflux in BuOH led to selective formation of pyrido[2,3-d]pyrimidin-5-ones or pyrido[2,3-d]pyrimidin-7-ones (containing an intact SMe group or resulting in its substitution with OBu group), depending on the nature of the acyl group. The possible substitution of SMe and OBu groups in pyridopyrimidinones was explored by using BnNH2. It was demonstrated that prior oxidation of SMe group with m-chloroperbenzoic acid allowed for simpler introduction of the NHBn moiety.