DMSO arbitrated Oxidative Annulation Followed by Homologated N-Alkylation: Microwave-Assisted Efficient and Greener Approach to Access 3-(3-Oxo-3-arylpropyl) Quinazolinones

A convenient, time efficient, tandem approach for the synthesis of medicinally privileged 3-(3-oxo-3-arylpropyl) quinazolinones is developed from ubiquitously available acetophenones and anthranilamide via microwave irradiation. This transition-metal-free reaction is initiated by the oxidative annulation of anthranilamide and in situ generation of α,β-unsaturated carbonyl compounds from aryl ketones in the presence of K2S2O8 and dimethyl sulfoxide. The latter acts as a source of two carbons [methine (=CH–) and methylene (–CH2–)] apart from being the solvent. The reaction is carried out under microwave irradiation which has the advantage of homogenous heat distribution, reducing the reaction time drastically compared to the conventional heating reaction.