Pyridopyrimidines. X. Synthesis of 3-substituted 2-thioxo-5,7-dimethylpyrido[2,3-d]pyrimidin-4(3H)-ones and their S-alkylation under phase transfer conditions
Cg. Dave et Kj. Patel, Pyridopyrimidines. X. Synthesis of 3-substituted 2-thioxo-5,7-dimethylpyrido[2,3-d]pyrimidin-4(3H)-ones and their S-alkylation under phase transfer conditions, J HETERO CH, 38(2), 2001, pp. 457-461
2-Thioxo-5,7-dimethylpyrido[2,3-d] pyrimidin-4(3H)-ones 3 were synthesized
by the cyclocondensation of 2-amino-3-carbethoxy-4,6-dimethylpyridine 1 wit
h methyl-N-aryldithiocarbamates 2 and compared with the condensation betwee
n 1 and aryl isothiocyanates 4. When a comparative study of N vs S alkylati
on of ambident 2-thioxo-5,7-dimethylpyrido[2,3-d]pyrimidin-4(3H)-ones 3 was
carried out under liquid-liquid and solid-liquid phase transfer conditions
using various alkylating agents 5, the S-alkylated products 6 were obtaine
d exclusively and selectively.