3,3'-(Phenyl-methyl-ene)bis-(1-ethyl-3,4-di-hydro-1H-2,1-benzo-thia-zine-2,2,4-trione): single-crystal X-ray diffraction study, quantum-chemical calculations and Hirshfeld surface analysis.

The title compound, C27H26N2O6S2, possesses potential anti-microbial, analgesic, and anti-inflammatory activity. This compound has three tautomeric forms, which relative energies were estimated with quantum-chemical calculations. All these tautomers (dienol form 7A, keto-enol form 7B, and diketo form 7C) were optimized by the M06-2X/cc-pVTZ method in a vacuum, using the PCM model with chloro-form and DMSO as solvent. The diketo form of the title compound proved to be the most energetically favourable as compared to the keto-enol or dienol forms. The diketo form can exist as three possible stereoisomers with the same configuration of one stereogenic center and different configurations of the stereogenic centers at two other atoms: ( R , R , R ), (S , R , S ) and ( R , R , S ). The ( R , R , S ) stereoisomer was found in the crystal phase. It was revealed that the thia-zine rings of equivalent benzo-thia-zine fragments have different conformations, (a sofa or a half-chair). The two bicyclic fragments connected through the phenyl-methyl-ene group are oriented almost orthogonal to each other, subtending a dihedral angle of 82.16(7)°.

2-Amino-4-(4-chloro-1-ethyl-2,2-dioxo-1H-benzo[c][1,2]thia-zin-3-yl)-7,7-dimethyl-5-oxo-5,6,7,8-tetra-hydro-4H-chromene-3-carbo-nitrile: single-crystal X-ray diffraction study and Hirshfeld surface analysis.

In the title compound, C22H22ClN3O4S, which has potential non-steroidal anti-inflammatory activity, the benzo-thia-zine and cyclo-hexenone rings both adopt a distorted sofa conformation while the 4H-pyrane ring adopts a very flattened sofa conformation. The two bicyclic fragments are skewed to each other, with the dihedral angle between their least-squares planes being 72.8 (1)°. In the crystal, the mol-ecules form a hydrogen-bonded chain parallel to the a axis due to N-H⋯O and N-H⋯Cl hydrogen bonds. Neighbouring chains are linked by C-H⋯N, C-H⋯O and π-π stacking inter-actions. Hirshfeld surface analysis was used to investigate the importance of the different types of inter-molecular inter-actions whose contributions are: H⋯H = 44.7%, O⋯H/H⋯O = 21.8%, N⋯H/H⋯N = 11.9%, C⋯H/H⋯C = 9.5%, Cl⋯H/H⋯Cl = 7.2%. Parts of the mol-ecule, viz. the phenyl ring and the ethyl side chain, are equally disordered over two sets of sites.

1,2-Benzoxathiin-4(3H)-one 2,2-dioxide - new enol nucleophile in three-component interaction with benzaldehydes and active methylene nitriles.

The reactivity of 1,2-benzoxathiin-4(3H)-one 2,2-dioxide was studied in multicomponent type reactions for the first time, namely, in a three-component interaction with active methylene nitriles and aromatic aldehydes in order to construct condensed 2-amino-4H-pyran derivatives. The reaction outcome strongly depended on the nature of an active methylene nitrile and an arenecarbaldehyde. Application of malononitrile resulted in novel 2-amino-4-aryl-4H-pyrano[3,2-c][1,2]benzoxathiine-3-carbonitrile 5,5-dioxides in most cases, whereas the utilization of ethyl cyanoacetate resulted in a complex mixture of products. In the last case, three different products were isolated depending on the arenecarbaldehyde used, namely ethyl 2-amino-4-aryl-4H-pyrano[3,2-c][1,2]benzoxathiine-3-carboxylate 5,5-dioxides, ethyl 2-cyano-3-arylacrylates, and salts of 3,3'-(arylmethylene)bis(4-hydroxybenzo[e][1,2]oxathiine 2,2-dioxides). Attempts to obtain separately ethyl 2-amino-4-aryl-4H-pyrano[3,2-c][1,2]benzoxathiine-3-carboxylate 5,5-dioxides enabled us to propose reaction pathways leading to these products. The salts were obtained for the first time. The preparative method for the synthesis of triethylammonium salts of 3,3'-(arylmethylene)bis(4-hydroxybenzo[e][1,2]oxathiine 2,2-dioxides) was proposed by the direct interaction of 1,2-benzoxathiin-4(3H)-one 2,2-dioxide with arenecarbaldehydes. The application of ammonium acetate as a catalyst allowed us to synthesize 7-aryl-7,14-dihydrobenzo[5,6][1,2]oxathiino[4,3-b]benzo[5,6][1,2]oxathiino[3,4-e]pyridine 6,6,8,8-tetraoxides containing a novel heterocyclic system. These facts, combined with our past investigations, allowed us to assert that the reactivity of enol nucleophiles that include the COCH2SO2X fragment has not been reported previously.