Chemoselective Synthesis of 2-Aryloxazines and 2-Aryltetrahydropyrimidines Using Nano-SiO_2 as a Reusable Solid Acid Catalyst under Thermal Conditions and Microwave Irradiation

摘要

Nano-SiO_2 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.