2-Acylthioacetamides in the Biginelli Reaction. -1,2,3,4-Tetrahydropyrimidine--5-carbothioamides (IV) are regioselectively obtained by Biginelli reaction of 2-acylthioacetamides with aromatic aldehydes. Oxidation of these carbothiamides by nitrous acid or other oxidants affords corresponding 5-carboxamides [cf. (V)]. -(KURMACH, M. N.; RYABITSKIY, A. B.; BRITSUN*, V. N.; Chem. Heterocycl.