Chemoselective synthesis of 2-aryloxazines and 2-aryltetrahydropyrimidines using nano-SiO2 as a reusable solid acid catalyst under thermal conditions and microwave irradiation

Abstract

Nano-SiO2 solid acid efficiently and selectively catalyzed the cyclocondensation reaction of arylnitriles with 3-amino-1-proopanol or 1,3-diaminopropane to afford their respective 2-substituted oxazines and tetrahydropyrimidines in high yields under thermal conditions and microwave irradiation. This methodology works effectively for the selective synthesis of mono-1,3-oxazines and mono-tetrahydropyrimidnes from dinitriles. The catalyst could be recycled and reused several times without a noticeable decrease in its activity.