Mannich Base Derivatives of 1,2-Benzisothiazolin-3-one: Syntheses, Crystal Structures and Bioactivities

Twelve Mannich base derivatives of 1,2-benzisothiazolin-3-one were synthesized by the reaction of 1,2-benzisothiazol-3（2H）-one （BIT） with different amines and formaldehyde. All the compounds were characterized by elemental analysis, IR spectroscopy, MS and 1H NMR. The crystal structure for 2,2＇-methylenebis（benzo[d]isothiazol-3（2H）-one） （3） has been determined by X-ray single-crystal structure analysis. Compound 3 （C15HIoN202S2） crystallizes in the monoclinic system, space group C2/c with a = 25.052（8）, b = 4.510（1）, c = 11.948（4） A, β = 100.992（4）°, V= 1325.2（7） A3, Mr = 314.37, Dc = 1.576 Mg.m-3, p = 0.25 mm-1, F（000） = 648, Z = 4, R = 0.034 and wR = 0.087. The preliminary biological test indicated that the compounds （2b, 2c） showed growth inhibitory activity against the gram-positive and gram-negative bacteria.

1,5-Dimethy-4-[(3-nitro-benzylidene)-amino]-2-pheyl-1,2-dihydro-pyrazol-3-one

The title compound C18H16N4O3 （Mr = 336.35） has been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. The Schiff base compound is a derivative of 4-aminoantipyrine. As expected, the molecular structure adopts a trans configuration about the central C=N double bond. It crystallizes in orthorhombic, space group P2dc with a = 7.632（1）, b = 7.816（1）, c = 28.082（5） A,β = 96.18（1）°, V= 1665.48（51） A^3, Z= 4, Dc = 1.341 g/cm^3, F（000） = 704,μ = 0.094 mm^-1, the final R = 0.0448 and wR = 0.1058. Of the total 3748 collections, 3105 were unique. In the molecule there exist two different planes of pyrazoline and C（11）-C（16） phenyl ring, which are approximately coplanar （r.m.s. de deviation from the combined mean plane is 0.03 A） with the dihedral angle between them of 9.8%.

Synthesis and Crystal Structure of Trans-4-[(5-(2,4-Dichlorophenoxy)-3-methyl-1-phenyl-1H-pyrazol-4-yl)methyleneamino]-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one

The title compound trans-4-[（5-（2,4-dichlorophenoxy）-3-methyl- 1-phenyl-1H-pyrazol-4-yl）methyleneamino]- 1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one 3 （C28H23Cl2N5O2, Mr = 532.41） has been synthesized and its crystal structure was determined by single-crystal X-ray diffraction analysis. It crystallizes in triclinic, space group P1- with a = 8.9438（4）, b = 11.6065（5）, c = 14.2215（6）A, α = 112.566（1）, β = 92.324（2）, γ = 102.91（1）°, V= 1315.65（10） A^3, Z = 2, Dc = 1.344 g/cm^3,μ（MoKa） = 0.282 mm^-1, λ = 0.71073 A, F（000） = 552, the final R = 0.0587 and wR = 0.1578 for 5071 observed reflections （I 〉 2σ（I））. X-ray analysis reveals that the product is a thermodynamically stable trans isomer. Intra- and intermolecular C（ 12）-H（12）…O（1） and C（28）-H（28）...O（1）# 1 hydrogen bonds were observed in the title compound.

Mass Spectrometry of 2a,4-Disubstituted 5-Benzoyl-2a,3,4,5-tetrahydro-2-phenoxy-azeto[1,2-a][1,5]benzodiazepin-1(2H)-ones Under Electron Impact Ionization Conditions

The mass spectrometric fragmentation of 2a,4-disubstituted 5-benzoyl-2a,3,4,5-tetrahydro-2-phenoxy-azeto{[1,2-a]}[1,5]benzodiazepin-1(2H)-ones has been investigated by means of mass-analyzed ion kinetic energy spectrometry under electron impact ionization conditions. All compounds tend to lose different moieties, such as phenoxy, phenoxy and H, and phenoxyketene. Both [M +-PhO] and [M +-PhOH] ions could further lose CO, and the [M +-PhOCHCO] ions could lose propene or styrene, PhCON, PhCOHN, and other fragments.

2-Thioxo-1,2-dihydrobenzo[d][1,3]thiazin-4-one:Synthesis,Crystal Structure and Its Photoinduced Proton Transfer Reaction

2-Thioxo-1,2-dihydrobenzo[d][1,3]thiazin-4-one （TDBTO）, a new thiazin-one derivative, was synthesized and investigated. The crystal structure of TDBTO （CsHsNOS2, Mr = 193.8） was determined by single-crystal X-ray diffraction. The crystal belongs to the triclinic system, space group P1 with a = 6.946（3）, b = 7.402（3）, c = 8.954（4）A, α = 66.931（7）°,β = 89.866（7）°, γ = 72.289（7）°, V = 399.8（3） A^3, Z = 2, Mr = 195.25, Dc = 1.622 g/cm^3,μ = 0.606 mm^-1, F（000） = 200, R = 0.0361 and wR = 0.1032. There exist intermolecular hydrogen bond of N（1）-H（1A）-..O（1） and weak C（6）-H（6A）...O（1） contact in the structure as well as face-to-face π-π stacking interactions between the benzene ring and the thiazin ring of an adjacent benzothiazin unit. The photoinduced proton transfer reaction, transforming the initial thione into thiol form, was found, and the latter form was characterized by UV absorption spectra, fluo-rescence spectra and infrared spectra.

4-[(Furan-2-ylmethylene)-amino]-1,5-dimethyl-1,2-dihyl-1,2-dihydo-pyrazol-3-one

The title compound （C16H15N3O2, Mr= 281.31） has been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. The Schiff base compound is a derivative of 4-aminoantipyrine. As expected, the molecular structure adopts a trans configuration about the C=N double bond. It crystallizes in the monoclinic system, space group P2 1/c with a = 11.150（3）, b = 9.906（3）, c = 13.624（4） A, β = 106.360（4）°, V= 1443.9（7） ,A^3, Z = 4, Dc = 1.294 g/cm^3, F（000） = 592,μ（MoKa） = 0.088 mm ^-1, R = 0.0577 and wR = 0.1214. Of the 5766 total reflections, 2540 were unique. In the molecule there exist two different planes of pyrazoline and O（2）-C（10） phenyl ring, which are approximately coplanar （r.m.s. de deviation from the combined mean plane is 0026 A） with the dihedral angle between them of 6.3°.

A novel and convenient synthesis of thiazolo[3,2-a]pyrimidin-7-ones and pyrido[1,2-a]pyrimidin-2-ones using Vilsmeier reagent

A novel route for the synthesis of thiazolo[3,2-a]pyrimidin-7-ones and pyrido[1,2-a]pyrimidin-2,ones from acetylated 2- aminothiazoles and 2-aminopyridines under Vilsmeier conditions has been developed. The plausible mechanism has also been proposed.

Recent advances on controllable and selective catalytic oxidation of cyclohexene

Because of multiple potential reaction sites and variable oxidation depths,oxidation of cyclohexene can lead to a mixture of products with different oxidation states and functional groups,such as 7-oxabicyclo[4.1.0]heptane,trans/cis-cyclohexane-1,2-diol,cyclohex-2-en-1-ol,cyclohex-2-en-1-one,and even adipic acid.These products are broadly and abundantly used intermediates in the chemical industry;therefore,controllable oxidation reactions for cyclohexene that can selectively afford the targeted products are synthetically valuable for applications in both the academy and industry,thus becoming the aim of synthetic and catalytic chemists in the field.Many reports on selective oxidation of cyclohexene have recently appeared in the literature because of its significance.This short review summarizes the recent advances on this subject,and the contents are mainly classified based on the chosen oxidants.We hope that this review can provide a useful guide for controllable and selective catalytic oxidation of cyclohexene for interested readers from both the academy and industry.

Three pairs of alkaloid enantiomers from the root of Isatis indigotica

Three pairs of enantiomerically pure alkaloids with diverse structure features, named isatindigoticoic acid A and epiisatindigoticoic acid A [(—)-1 and(+)-1], phaitanthrin A and epiphaitanthrin A [(—)-2 and(+)-2], and isatindopyrromizol A and epiisatindopyrromizol A [(—)-3and(+)-3], respectively, were isolated from an aqueous extract of the roots of Isatis indigotica. Racemic and scalemic mixtures of these enantiomers were separated by HPLC on a chiral semi-preparative column.Their structures including absolute configurations were determined by extensive spectroscopic analysis in conjunction with the calculation of electronic circular dichroism(ECD) spectra. The enantiomer pairs possess parent structures of 2-oxo-1,2,3,4-tetrahydroquinoline-4-carboxylic acid, indolo[2,1-b]quinazolinone, and 3-thioxohexahydro-1H-pyrrolo[1,2-c]imidazol-1-one, respectively. Except for phaitanthrin A[(—)-2] which the configuration was previously undetermined, these compounds are new enantiomeric natural products.