Facile and Rapid Synthesis of ۳,۴-Dihydropyrimidin-۲-(۱H)-ones and Thione Derivatives Through the Biginelli Protocol Using N-Methylimidazolium Acetate

Some protic ionic liquids (PILs) were synthesized by the direct neutralization reaction of N-methylimidazole and ۴-N,N-dimethylaminopyridine as nitrogen-containing heterocyclic organic bases with acetic acid and trifluoroacetic acid. The relative acidity of the prepared ionic liquids was evaluated by Hammet's acidity function using UV-Vis spectroscopy. The catalytic effects of the obtained ionic liquids were investigated in the synthesis of ۳,۴-dihydropyrimidin-۲-(۱H)-ones and thione derivatives through Biginelli reaction. AmongN-methylimidazolium acetate [MImH][OAc], N-methylimidazolium trifluoroacetate [MImH][CF۳CO۲], ۴-N,N-dimethylaminopyridinium acetate [DMAPH][OAc] and ۴-N,N-dimethylaminopyridinium trifluoroacetate [DMAPH][CF۳CO۲], [MImH][OAc] provided the best results. Using ۵ mol% of [MImH][OAc] as a catalyst, ۳,۴-dihydropyrimidin-۲-(۱H)-ones and thione derivatives were obtained in high to excellent yields at ۱۰۰ ºC during ۱۵-۵۰ min.

کلیدواژه ها:

Biginelli reaction ، ۳ ، ۴-Dihydropyrimidin-۲-(۱H)-one ، N-Methylimidazolium acetate ، Protic ionic liquid