Gomes, Ligia R.Low, John NicolsonCagide, FernandoBorges, Fernanda2019-10-242019-10-2420152056-9890http://hdl.handle.net/10284/8168he title compounds, 6-(2-hy­droxy­benz­yl)-5H-thia­zolo[3,2-a]pyrimidin-5-one, C13H8N2O3S, (1), and 6-(2-hy­droxy­benz­yl)-3-methyl-5H-thia­zolo[3,2-a]pyrimidin-5-one, C14H10N2O3S, (2), were synthesized when a chromone-3-carb­oxy­lic acid, activated with (benzotriazol-1-yl­oxy)tripyrrolidinyl­phospho­nium hexa­fluorido­phosphate (PyBOP), was reacted with a primary heteromamine. Instead of the expected amidation, the unusual title thia­zolo­pyrimidine-5-one derivatives were obtained serendipitously and a mechanism of formation is proposed. Both compounds present an intra­molecular O-H...O hydrogen bond, which generates an S(6) ring. The dihedral angles between the heterocyclic moiety and the 2-hydroxybenzoyl ring are 55.22 (5) and 46.83 (6)° for (1) and (2), respectively. In the crystals, the mol­ecules are linked by weak C-H...O hydrogen bonds and [pi]-[pi] stacking inter­actions.engCrystal structureThia­zoleConformationSupra­molecular structureHydrogen bondingjournal article10.1107/S2056989015011044