A FACILE ENTRY TO PYRIMIDINE-DERIVATIVES - SYNTHESIS OF 5-(1,3-DITHIOLAN DITHIAN-2-YLIDENE) AND PYRANO[2,3-D]PYRIMIDINES/

Synthesis of various pyrimidine derivatives starting from 1, 3-diaryl- 2-thiobarbituric acids 1 has been described. Treatment of 1 with carbo n disulfide in the presence of triethylamine followed by reaction with appropriate alkyldihalides gives the corresponding ketene dithioaceta l derivatives 2-4. On the other hand the reaction of 1 with acetyl chl oride results in the formation of 5-acetyl derivatives 6 which on cond ensation with malononitrile in the presence of ammonium acetate provid e the bicyclic imines 7. These imines on hydrolysis with HBr/AcOH yiel d the pyrano[2, 3-d]pyrimidines 8.