A traceless polymer-supported synthesis of 4-benzoylquinazolines was developed using the following commercially available building blocks: Fmoc-α-amino acids, 2-nitrobenzensulfonyl chlorides and α-bromoacetophenones. The acyclic intermediates underwent base-catalyzed rearrangement involving C–C and N–N bond formation followed by ring expansion and yielded resin-bound dihydroquinazoline-2-carboxylic
When a mixture of 4-chloroquinazoline (7), an aromatic aldehyde 6, sodium hydride, and a catalytic amount of 1, 3-dimethylbenzimidazolium iodide (1) in tetrahydrofuran (THF) was refluxed with stirring for an appropriate time, the chlorine atom of 7 was replaced with the aroyl group, and the 4-aroylquinazolines 10 were obtained in excellent yields. Similar treatments of 4-chloro-2-methylquinazoline (8) and 4-chloro-2-phenylquinazoline (9) led to the 4-aroyl-2-methylquinazolines 11 and the 4-aroyl-2-phenylquinazolines 12, respectively.Use of N, N-dimethylformamide (DMF) instead of THF as the reaction solvent in the above reaction reduced the reaction time and increased the yields of the ketones 10 and 12 as compared with those in THF.
Synthesis of indoles and quinazolines <i>via</i> additive-controlled selective C–H activation/annulation of <i>N</i>-arylamidines and sulfoxonium ylides