Synthesis of novel beta-aryl-beta-(methylthio)acroleins via Vilsmeier-Haack protocol as potential 1,3-dielectrophilic three-carbon building blocks

A new general route for the synthesis of novel beta-aryl-beta-(methylthio)acroleins, a class of stable potential 1,3-dielectrophilic synthons, has been reported. The overall protocol involves treatment of either beta-chloroacroleins or their precursor iminium salts (generated in situ from the corresponding active methylene ketones under Vilsmeier-Haack reaction conditions) with S,S-dimethyldithiocarbonates (DDC)/aqueous KOH in either a one-pot or two-step process. The dimethyldithiocarbonate (DDC)/30% aqueous KOH has been shown to be an excellent source of methylthiolate anion. (C) 2014 Elsevier Ltd. All rights reserved.

Acid-catalysed cyclisations: structures of novel products isolated in the reaction of 2-[3-(2,6-dimethoxyphenyl)but-2-enyl]-2-methylcyclopentane-1,3-dione with MeOH-HCl

Reaction of the title compound (1a) with anhydrous MeOH-HCl gave 2-endo-(2,6-dimethoxyphenyl)-2-exo-methyl-5-methylbicyclo[3.2.1]octane-6,8-dione (3a), 1,5,14-timethoxy-5,8-seco-6,7-dinorestra-1,3,5(10),9(11)-tetraen-17-one (4), 1,5-dimethoxy-5,8-seco-6,7-dinorestra-1,3,5(10),8,14-pentaen-17-one (5), and 3,4,5,6-tetrahydro-2,7-dimethoxy-3,6-dimethyl-3,2,6-(13-oxopropan[1]yI[3]ylidene)-2H-1-benzoxocin (6). Structures assigned to compounds (3a), (4), and (6) are based on spectral data. The exo-tricyclic acetal structure (6) was further confirmed by the analysis of the 1H n.m.r. spectra of the isomeric alcohols (11) and (12), obtained by sodium borohydride reduction of (6).

N-{1-[(3-Bromopropyl)aminocarbonyl]ethyl}-2-(2-nitrobenzenesulfonamido)propionamide

In the title compound, C15H21BrN4O6S, all three NH groups are involved in intermolecular N-H center dot center dot center dot O interactions which, together with two intermolecular C-H center dot center dot center dot O contacts, lead to a continuous antiparallel beta-sheet structure. There are no pi-pi interactions between molecules, and two C-H center dot center dot center dot pi interactions primarily govern the linkage between sheets.

1,3-Dipolar cycloaddition reaction of ?,?-unsaturated esters and lactones with diazomethane

1,3-Dipolar cycloaddition of diazomethane to the alpha,beta-unsaturated esters and lactones such as 2-4, 6-8, 10 and 13 occurs in a stereoselective manner affording conjugated Delta(2)-pyrazolines. E and Z isomers of D-mannitol lead to identical product which was cyclised to investigate the absolute stereochemistry of the product. The regiospecificities of all the reactions are consistent with FMO coefficients obtained through AM1 calculations.

Reduction of oxygen impurity at GaN/beta-Si(3)N(4)/Si interface via SiO(2) to Ga(2)O conversion by exposing of Si surface under Ga flux

The removal of native oxide from Si (1 1 1) surfaces was investigated by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectra (SIMS) depth profiles. Two different oxide removal methods, performed under ultrahigh-vacuum (UHV) conditions, were carried out and compared. The first cleaning method is thermal desorption of oxide at 900 degrees C. The second method is the deposition of metallic gallium followed by redesorption. A significant decrease in oxygen was achieved by thermal desorption at 900 degrees C under UHV conditions. By applying a subsequent Ga deposition/redesorption, a further reduction in oxygen could be achieved. We examine the merits of an alternative oxide desorption method via conversion of the stable SiO(2) surface oxide into a volatile Ca(2)O oxide by a supply of Ga metals. Furthermore, ultra thin films of pure silicon nitride buffer layer were grown on a Si (1 1 1) surface by exposing the surface to radio-frequency (RF) nitrogen plasma followed by GaN growth. The SIMS depth profile shows that the oxygen impurity can be reduced at GaN/beta-Si(3)N(4)/Si interfaces by applying a subsequent Ga deposition/redesorption. (C) 2011 Elsevier B.V. All rights reserved.

Non-existence of tight neighborly triangulated manifolds with beta(1)=2

All triangulated d-manifolds satisfy the inequality ((f0-d-1)(2)) >= ((d+2)(2))beta(1) for d >= 3. A triangulated d-manifold is called tight neighborly if it attains equality in this bound. For each d >= 3, a (2d + 3)-vertex tight neighborly triangulation of the Sd-1-bundle over S-1 with beta(1) = 1 was constructed by Kuhnel in 1986. In this paper, it is shown that there does not exist a tight neighborly triangulated manifold with beta(1) = 2. In other words, there is no tight neighborly triangulation of (Sd-1 x S-1)(#2) or (Sd-1 (sic) S-1)(#2) for d >= 3. A short proof of the uniqueness of K hnel's complexes for d >= 4 under the assumption beta(1) not equal 0 is also presented.

3-(1,3-Dioxolan-2-yl)-2-hydrazino-7-methylquinoline

In the title molecule, C13H15N3O2, the dihedral angle between the mean plane of the 1,3-dioxolane group and the 2-hydrazino-7-methylisoquinoline unit is 85.21 (5)degrees. The conformation of the molecule is influenced by bifurcated N-H center dot center dot center dot(O, O) and N-H center dot center dot center dot N intramolecular hydrogen bonds. In the crystal structure, molecules are linked via intermolecular N-H center dot center dot center dot O hydrogen bonds, forming extended chains along [001].

1,3-Dimethyl-2,6-diphenylpiperidin-4-one

In the title moleclue, C19H21NO, the 4-piperidone ring adopts a chair conformation in which the two benzene rings and the methyl group attached to C atoms all have equatorial orientations. In the crystal structure, centrosymmetric dimers are formed through weak intermolecular C-H center dot center dot center dot O hydrogen bonds [the dihedral angle between the aromatic rings is 58.51 (5)degrees].

Highly efficient C-8 oxidation of substituted xanthines with substitution at the 1-, 3-, and 7- positions using biocatalysts

A bacterial consortium consisting of strains belongings to the genus Klebsiella and Rhodococcus quantitatively converts 1-, 3- and 7-substituted xanthines to their respective 8-oxo compounds.

Synthesis, antimicrobial and cytotoxic activities of 1,3,4-oxadiazoles, 1,3,4-thiadiazoles and 1,2,4-triazoles

A new class of 1,3,4-oxadiazoles were prepared from acid hydrazides on treatment with different carboxylic acids in the presence of phosphorus oxychloride. Interconversion of oxadiazoles to thiadiazoles and triazoles was carried out with appropriate reagents. The antimicrobial and cytotoxic activities of compounds 7a-d to 12a-d were tested. Compounds 10d and 12d showed pronounced antimicrobial activity. Further, compound 10d exhibited maximum cytotoxicity. (C) 2008 Elsevier Masson SAS. All rights reserved.

Molecular-Conformation of 1,3-Pyridylphenylureas by H-1 and C-13 NMR-study

1H and 13C NMR spectra are reported for several 1,3-pyridylphenyl ureas. Analysis of the spectra yielded the chemical shifts. The variations in the chemical shifts have been discussed in terms of the molecular conformations.

A polarized, twisted, ethylene: structure of methyl 2-(1,3-dimethyl-2-imidazolidinylidene)-3-oxobutyrate dihydrate, C10H16N2O3.2H2O

Mr = 248, monoclinic, P21/n, a = 12.028 (2), b=7.168(2), c= 15.187(5)A, fl=91.88(2) °, Z= 4, V= 1308.6,~3, Din= 1.26, Dx= 1.263 Mgm -3, 2 (Cu Ka) = 1.5418 .A, g = 0.86 mm -1, F(000) = 536, T= 293 K. Final R = 5.6% for 2120 observed reflexions. Owing to the push-pull effect, the C=C bond distance is as long as 1.464 (2)/k with the twist angle about the bond 62.6.

Push-pull ethylenes: the structures of 3-(2-imidazolidinylidene)-2,4-pentanedione (I), C8H12N2O2, and 3-(1,3-dimethyl-2-imidazolidinylidene)-2,4-pentanedione trihydrate (II), C10H16N2O2.3H2O

(I): Mr= 168, triclinic, P1, Z=2, a= 5.596 (2), b = 6.938 (3), c = 10.852 (4) A, ~t= 75.64 (3), fl= 93.44 (3), ),= 95.47 (3) °, V= 406.0A 3, Din= 1.35 (by flotation using carbon tetrachloride and n-hexane), D x= 1.374 Mg m -3, g(Mo Kct, 2 = 0.7107 A) = 1.08 cm -l, _F(000) = 180, T= 293 K. (II): Mr= 250, triclinic, P1, Z= 2, a = 7.731(2), b=8.580(2), c=11.033(3)A, a= 97-66 (2), fl= 98.86 (2), y= 101.78 (2) °, V= 697.5 A 3, D m = 1.18 (by flotation using KI solution), Dx= 1.190Mgm -3, g(MoKa, 2=0.7107A)= 1.02 cm -1, F(000) = 272, T= 293 K. Both structures were solved by direct methods and refined to R = 4.4% for 901 reflexions for (I) and 5.7% for 2001 reflexions for (II). The C=C bond distances are 1.451 (3) A in (I) and 1.468 (3)A in (II), quite significantly longer than the C=C bond in ethylene [1.336 (2).~; Bartell, Roth, Hollowell, Kuchitsu & Young (1965). J. Chem. Phys. 42, 2683-2686]. The twist angle about the C=C bond in (II) is 72.9 (5) ° but molecule (I) is essentially planar, the twist angle being only 4.9 (5) ° .