Vk. Ahluwalia et al., A FACILE ENTRY TO PYRIMIDINE-DERIVATIVES - SYNTHESIS OF 5-(1,3-DITHIOLAN DITHIAN-2-YLIDENE) AND PYRANO[2,3-D]PYRIMIDINES/, Indian journal of chemistry. Sect. B: organic chemistry, including medical chemistry, 35(7), 1996, pp. 673-676
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.