Crystal Structure of 3-(4-nitro-) phenylsulfonyloxyisothiazole NO_2C_6H_4SO_3C_3H_2NS

C9H6N2O5S2 is monoclinic, space group P21/n, for 1278 observed reflections . The result indicates clearly the sul-fonylation takes place at oxygen. According to the data of bond lengths, the isothiazole ring displays aromaticity in some way.

Synthesis,Characterization and Antibacterial Activity of 3-(2-(Heterocyclo-2-ylthio)-ethoxy)benzo[d]isothiazoles

Seven novel 3-（2-（heterocyclo-2-ylthio）ethoxy）benzo[d]isothiazoles（3a^3g） have been synthesized and characterized by ESI-MS and 1H and 13 C NMR spectra. The crystal structures of 3a and 3g have been determined. Compound 3a（C（11）H（11）N5O1S2） belongs to the monoclinic system and 3g（C（12）H（11）N3OS3） to the triclinic system. The title compounds show excellent in vitro antibacterial activities, with the minimum inhibitory concentrations varying from 4 to 32 ug/m L.

Design, synthesis, and in vitro activity of methylisoxazole/isothiazole amides as BACE1 inhibitors

Based on the structure of compound B51（IC_（50） = 37.4 μM）, which was discovered as hit in a previous virtual screen, a series of methylisoxazole/isothiazole amide derivatives were designed and synthesized as BACE1 inhibitors. The methoxyphenylpyrimidone fragment of B51 was transformed into a methoxyphenylmethylisoxazole/isothiazole moiety to reduce the molecular weight while retaining the ability to fit into the S1＇ and S2＇ subpocket of BACE1 as predicted by docking studies. The effects of BACE1 inhibition and the structure-activity relationships were analyzed. Among all 20 designed compounds, 5t exhibited almost 10-fold improved potency（IC_（50） = 5.33 μM） compared to B51 in the BACE1 inhibition assay. Additionally, it has exhibited ＂rapid binding, slow dissociation＂ kinetics in SPR analysis, suggesting a longer inhibitory effect than B51. All acquired methylisoxazole/isothiazole derivatives were small in size and safe to normal cells, which allow them represent a novel scaffold for BACE1 inhibitor design.

Synthesis, Crystal Structure and Biological Activity of 2-(3,4-Dichloroisothiazol-5-yl)-4-(trifluoromethyl)-4,5-dihydrothiazol-4-yl-3-methylbenzoate

The title compound diethyl 2-（3,4-dichloroisothiazol-5-yl）-4-（trifluoromethyl）-4,5- dihydrothiazol-4-yl-3-methylbenzoate （C15H9C12F3N202S2, Mr = 441.26） was prepared from methyl 3,4-dichloroisothiazole-5-carboxylate as the starting material by four steps of reaction. Its structure was characterized by IR, 1H-NMR, 13C-NMR, EA and single-crystal X-ray diffraction. The crystal of the title compound belongs to the monoclinic system, space group P2dc with a = 8.8437（18）, b = 16.128（3）, c = 12.305（3） A, β = 91.68（3）°, V= 1754.4（6） A3, Z = 4, Dc = 1.671 g/cm3,μ（MoKa） = 0,71073 mm^-1, F（000） = 888, R = 0.0384 and wR = 0.0778. Weak π-π interactions occur between the isothiazole rings and phenyl rings of adjacent molecules to form a one-dimensional chain and stabilize the crystal structure. Bioassay indicates that the title compound has good activity against the fungi and TMV tested.

Theoretical Study of Kinetics and Thermodynamics of Hetero Diels-Alder Reaction of Thiazole and Isothiazol with Thiophene-2,5-dione

DFT methods have been used to study the hetero Diels-Alder reaction of thiazole and isothiazole with thiophen-2,5-dione.The thermodynamic and kinetic parameters were calculated.The relative stabilities of the transition structures corresponding to the endo/exo stereoisomers have been rationalized on the basis of the secondary molecular orbital interactions.NBO analysis was carried out to calculate the synchronicity index.It was shown that all reactions are synchronous.A HOMO-LUMO energy gap shows both reactions are normal electron demand.