Sp. Bhatti et al., SYNTHESIS OF CHROMON-6 8-YLETHANOIC ACIDS FROM 6/8-ACETYLCHROMONES/, Indian Journal of Heterocyclic Chemistry, 7(2), 1997, pp. 89-92
The reaction of cyclic secondary amines and sulphur, in presence of p-
toluenesulphonic acid with substituted 6/8-acetylchromones afforded th
e corresponding thioamides which on hydrolysis gave the title acids.