Dear Sir. Concerning your issue about the best solvent to synthesis quinazolinone derivative from benzoxazine with aniline with microwave. Simple, convenient, and green synthetic protocols have been developed for the one pot synthesis of 2,3-disubstituted quinazolin-4(3H)-ones and 2-styryl-3-substituted quinazolin-4(3H)-ones under catalyst and solvent free conditions. The multicomponent reaction (3-MCR) involving isatoic anhydride, an amine, and orthoester afforded the 2,3-disubstituted quinazolin-4(3H)-ones in excellent yields under classical heating at 120 °C for 5 h or under microwave irradiation at 140 °C for 20–30 min. The use of ammonium acetate instead of the amine provides the 2-substituted quinazolin-4(3H)-ones. The reactions are compatible with various substituted isatoic anhydrides, aryl/heteroaryl/alkyl/cycloalkyl amines, and orthoesters. The strategies are extended to the one pot tandem condensation involving isatoic anhydride, an amine, orthoester, and aldehyde to afford highly functionalized (E)-3-aryl/heteroaryl-2-styrylquinazolin/(2-(heteroaryl)vinyl)quinazolin-4(3H)-ones. The applications of the methodologies are demonstrated through the synthesis of various drugs which act on the central nervous system such as methaqualone, mebroqualone, mecloqualone, piriquialone, and diproqualone. Solid supported microwave synthesis of some 3-substituted-4-(2H)-quinazolinones has been carried out by the reaction of anthranilic acid, formaldehyde and primary aromatic amines. The usage of hazardous reagents and organic solvents has been avoided. The reactions were conducted in presence of acidic alumina where formaldehyde entered into cycloaddition to yield the quinazolinone derivatives. The reactions completed within 2-4 minutes with 82-94% of yields in microwave reactions while it took 5-7 hours for completion affording only 56-68% of the yields in conventional reactions. The synthesized quinazolinone derivatives showed moderate to promising antibacterial and antifungal activities. I think the following below links and the attached file may help you in your analysis:

http://pubs.rsc.org/en/content/articlelanding/2015/ra/c5ra03888j#!divAbstract

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3500554/

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Synthesis quinazolinone derivative with microwave, you can carry out the reaction with out solvent where aniline  will play the role of a solvent .

Synthesis of quinazolinone derivatives from benzoxazine with anilines under Microwave irradiation are solvent free and greener method.

Thank you for all your answer sir.

Best regard, darmawan