Synthesis and Reactions of some 2-Vinyl-3H-quinazolin-4-ones

A simple, high-yielding synthesis of 2-vinyl-3H-quinazolin-4-one, 2-(1-chlorovinyl)-3H-quinazolin-4-one and 2-(1-bromovinyl)-3H-quinazolin-4-one. The 2-vinylquinazolinones 11a and 14 participate readily in nucleophilic addition reactions. Treatment with both carbon and nitrogen nucleophiles results in a clean conversion into a variety of 2-substituted 3H-quinazolin-4-one derivatives. The 2-(1-halovinyl)-3H-quinazolin-4-ones 11b and 11c reacted with carbon nucleophiles to give several derivatives of 2-substituted 3H-quinazolin-4-one, such as dihydrofurancarboxylic ethyl ester 23.