Crystal structures of two 6-(2-hy-droxy-benzo-yl)-5H-thia-zolo[3,2-a]pyrimidin-5-ones

Ligia R Gomes; John Nicolson Low; Fernando Cagide; Fernanda Borges

doi:10.1107/S2056989015011044

Crystal structures of two 6-(2-hy-droxy-benzo-yl)-5H-thia-zolo[3,2-a]pyrimidin-5-ones

Acta Crystallogr E Crystallogr Commun. 2015 Jun 13;71(Pt 7):766-71. doi: 10.1107/S2056989015011044. eCollection 2015 Jul 1.

Authors

Ligia R Gomes¹, John Nicolson Low², Fernando Cagide³, Fernanda Borges³

Affiliations

¹ FP-ENAS-Faculdade de Ciências de Saúde, Escola Superior de Saúde da UFP, Universidade Fernando Pessoa, Rua Carlos da Maia, 296, P-4200-150 Porto, Portugal ; REQUIMTE/Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, 4169-007 Porto, Portugal.
² Department of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen AB24 3UE, Scotland.
³ CIQUP/Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, 4169-007 Porto, Portugal.

Abstract

The title compounds, 6-(2-hy-droxy-benz-yl)-5H-thia-zolo[3,2-a]pyrimidin-5-one, C13H8N2O3S, (1), and 6-(2-hy-droxy-benz-yl)-3-methyl-5H-thia-zolo[3,2-a]pyrimidin-5-one, C14H10N2O3S, (2), were synthesized when a chromone-3-carb-oxy-lic acid, activated with (benzotriazol-1-yl-oxy)tripyrrolidinyl-phospho-nium hexa-fluorido-phosphate (PyBOP), was reacted with a primary heteromamine. Instead of the expected amidation, the unusual title thia-zolo-pyrimidine-5-one derivatives were obtained serendipitously and a mechanism of formation is proposed. Both compounds present an intra-molecular 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 mol-ecules are linked by weak C-H⋯O hydrogen bonds and π-π stacking inter-actions.

Keywords: conformation; crystal structure; hydrogen bonding; supramolecular structure; thiazole; π–π stacking interactions.