A facile synthesis of novel biologically active 4-hydroxy-N'-(benzylidene)-2H-benzo[e][1,2]thiazine-3-carbohydrazide 1,1-dioxides.

A novel series of potentially biologically active 4-hydroxy-N'-(benzylidene)-2H-benzo[e][1,2]thiazine-3-carbohydrazide 1,1-dioxides were synthesized starting from ultrasonic mediated N-alkylation of sodium saccharin with methyl chloroacetate. Ring expansion of methyl(1,1-dioxido-3-oxo-1,2-benzisothiazol-2(3H)-yl)acetate followed by its hydrazinolysis afforded 4-hydroxy-2H-1,2-benzothiazine-3-carbohydrazide 1,1-dioxide which was reacted in a straight forward manner with various benzaldehydes in an ultrasonic bath to get the title compounds. All of the synthesized compounds were subjected to preliminary evaluation for their antibacterial and DPPH radical scavenging activities.

Ethyl 5-amino-1-(4-chloro-2-nitro-phen-yl)-1H-pyrazole-4-carboxyl-ate.

In the mol-ecule of the title compound, C(12)H(11)ClN(4)O(4), the pyrazole ring is coplanar with the amino and ethoxy-carbonyl groups within 0.026 (2) and 0.105 (2) Å, respectively. The C(6) ring of the 4-chloro-2-nitro-phenyl group is twisted by 53.58 (4)° relative to the plane of the pyrazole ring. The planar structure of the pyrazole ring is stabilized by an intra-molecular N-H⋯O hydrogen bond between its substituents. Neighbouring mol-ecules are linked through inter-molecular N-H⋯N and N-H⋯O hydrogen bonds, giving rise to one-dimensional tapes along the b axis. Mol-ecules in the chain are linked to those of an adjacent chain through weak C-H⋯O inter-actions, forming a three-dimensional network.

N-(4-Chloro-2-nitro-phen-yl)methane-sulfonamide.

The title compound, C(7)H(7)ClN(2)O(4)S, is of inter-est as a precursor to biologically active substituted quinolines. Its structure resembles those of the previously reported N-phenyl-methane sulfonamide and its 4-nitro, 4-fluoro and 4-bromo derivatives, with slightly different geometric parameters. An intra-molecular N-H⋯O hydrogen bond gives rise to a six-membered ring. Inter-molecular C-H⋯O contacts stabilize the crystal packing.

Methyl 4-eth-oxy-2-methyl-2H-1,2-benzothia-zine-3-carboxyl-ate 1,1-dioxide.

In the crystal structure of the title compound, C(13)H(15)NO(5)S, the mol-ecules exhibit weak S=O⋯H-C and C=O⋯H-C inter-molecular inter-actions and arrange themselves into centrosymmetric dimers by means of π-π inter-actions (ring centroids are separated by 3.619 Å, while the closest C⋯C contacts are 3.514 Å). 1,2-Benzothia-zines of this kind have a range of biological activities and are used as medicines in the treatment of inflammation and rheumatoid arthritis.

Synthesis of potential biologically active 1,2-benzothiazin-3-yl-quinazolin-4(3H)-ones.

A series of potential biologically active 2-(4-hydroxy-1,1-dioxido-2H-1,2-benzothiazin-3-yl)quinazolin-4(3H)-ones was synthesized in a straight forward manner by condensation of respective 4-hydroxy-1,2-benzothiazine-1,1-dioxides with anthranilamide followed by simple and high throughput cyclization of N-[2-(aminocarbonyl)phenyl]-4-hydroxy-1,2-benzothiazine-3-carboxamide-1,1-dioxides. All the synthesized compounds were subjected to preliminary evaluation for their biological activity against Gram positive and Gram negative bacteria. Some of the assayed compounds showed marked activity against Bacillus subtilis.