摘要:
Condensation of o-cyanomethylbenzoic acids with esters of 2-aminothiophene-3-carboxylic and 3-amino-thiophene-2-carboxylic acids to give isomeric 2-(4-oxo-3,4-dihydrothieno[2,3-d]pyrimidin-2-ylmethyl)-benzoic acids and their ethyl and phenacyl esters. Methylation of esters occurs at N-3. The spectroscopic characteristics of the positional isomers are compared at the level of carboxylic acids, their esters, and methylated products.