General Approach for Regioselective Synthesis of Fused Phosphono Substituted-Heterocycles. Reactions of Bismethylene-1,3-dithietane with H -Nucleophiles

A number of [2,1- b ] fused phosphono substituted-thioxopyranes, -oxadiazines, and -thiazines were obtained from the reactions of the corresponding f -carbonyl methylenes and f -carbonylmonohydrazones with phosphenato-substituted 1,3dithietane 1 .     

PHOTOCHEMISTRY OF PESTICIDES, 13.1 SOME PHOTOREACTIONS OF O,O-DIETHYL-O-(4-METHYL-2-OXO-2H-1-BENZOPYRAN-7-YL)-PHOSPHOROTHIOATE (POTASAN®)

Abstract

UV-irradiation (δ > 313nm) of O,O-diethyl-O-(4-methyl-2-oxo-2H-1-benzopyran-7-yl)-phosphoro-thioate (Potasan®) la in chloroform and/or methanol with and without singlet oxygen results in the formation of the 2-oxo-2H-1-benzopyran-phosphate 2 the 3,3′-bipotasan dehydrodimer 3, and 7-ethoxy-4-methyl-2-oxo-2H-1-benzopyran 4: the mechanisms of formation, especially for 4 are discussed.     

An improved variational iteration method for solving coupled KdV and Boussinesq-like B(m, n) equations

In this article, we implement a new analytical technique; He’s variational iteration method for solving the coupled KdV and Boussinesq-like equations. In this method, first general Lagrange multipliers are introduced to construct correction functional for the problems. The multipliers in the functional can be identified optimally via the variational theory. Next the components of obtained iteration formulae defined by partial sum of other sequence, specially constructed according to Adomian’s decomposition method (ADM). Also according to ADM we used a partial sum of Adomian polynomials instead of nonlinear terms in iteration formulae. The initial approximations can be freely chosen with possible unknown constants, which can be determined by imposing the initial conditions. The results reveal that the proposed method is very effective and can be applied for other nonlinear problems.     

Chapman-Enskog-maximum entropy method on time-dependent neutron transport equation

The time-dependent neutron transport equation in semi and infinite medium with linear anisotropic and Rayleigh scattering is proposed. The problem is solved by means of the flux-limited, Chapman-Enskog-maximum entropy for obtaining the solution of the time-dependent neutron transport. The solution gives the neutron distribution density function which is used to compute numerically the radiant energy density E(x,t), net flux F(x,t) and reflectivity R_f. The behaviour of the approximate flux-limited maximum entropy neutron density function are compared with those found by other theories. Numerical calculations for the radiant energy, net flux and reflectivity of the proposed medium are calculated at different time and space.     

Solvent and linker influences on AQ(*-)/dA(*+) charge-transfer state energetics and dynamics in anthraquinonyl-linker-deoxyadenosine conjugates

The goal of this work is to produce high yields of long-lived AQ(*-)/dA(*+) charge transfer (CT) excited states (or photoproducts). This goal fits within a larger context of trying generally to produce high yields of long-lived CT excited states within DNA nucleoside conjugates that can be incorporated into DNA duplexes. Depending upon the energetics of the anthraquinonyl (AQ) (3)(pi,pi) state as well as the reduction potentials of the subunits in particular anthraquinonyl-adenine conjugates, CT quenching of the AQ (3)(pi,pi*) state may or may not occur in polar organic solvents. In MeOH, bis(3',5'-O-acetyl)-N(6)-(anthraquinone-2-carbonyl)-2'-deoxyadenosine (AQCOdA) behaves as intended and forms a (3)(AQ(*-)/dA(*+)) CT state with a lifetime of 3 ns. However, in nonpolar THF the AQ(*-)/dA(*+) CT states of AQCOdA are too high in energy to be formed, and in DMSO a (1)(AQ(*-)/dA(*+)) CT state is formed but lives only 6 ps. Although the lowest energy excited state for AQCOdA in MeOH is a (3)(AQ(*-)/dA(*+)) CT state, for N(6)-(anthraquinone-2-methylenyl)-2'-deoxyadenosine (AQMedA) in the same solvent it is a (3)(pi,pi*) state. Changing the linking carbonyl in AQCOdA to methylene in AQMedA makes the anthraquinonyl subunit harder to reduce by 166 mV. This raises the energy of the (3)(AQ(*-)/dA(*+)) CT state above that of the (3)(pi,pi*) in AQMedA. The conclusion is that anthraquinonyl-dA conjugates will not have lowest energy AQ(*-)/dA(*+) CT states in polar organic solvents unless the anthraquinonyl subunit is also substituted with an electron-withdrawing group that raises the AQ-subunit's reduction potential above that of AQ. A key finding in this work is that the lifetime of the (3)(AQ(*-)/dA(*+)) CT excited state (ca. 3 ns) is ca. 500-times longer than that of the corresponding (1)(AQ(*-)/dA(*+)) CT excited state (ca. 6 ps).'     

Synthesis and reactions of 2‐chloro‐2‐(hydroximino)‐1‐(4‐methyl‐2‐phenylthiazol‐5‐yl)ethanone

3‐Nitrosoimidazo[1,2‐a]pyridine, 3‐nitrosoimidazo[1,2‐a]pyrimidine, 3‐nitrosoquinoxaline, 2‐nitroso‐4H‐benzo[b]thiazine, 2‐nitroso‐4H‐benzo[b]oxazine, isoxazoles, isoxazolo[3,4‐d]pyridazines and pyrrolo[3,4‐d]isoxazole‐4,6‐dione were synthesized from 2‐chloro‐2‐(hydroximino)‐1‐(4‐methyl‐2‐phenylthiazol‐5‐yl)ethanone and different reagents. Structures of the newly synthesized compounds were confirmed by elemental analysis and spectral data.     

Mercury(II) cyanide coordination polymer with dinuclear gold(I) amidinate. Structure of the 2-D [Au2(2,6-Me2-formamidinate)2].2Hg(CN)2.2THF complex

The dinuclear gold(I) amidinate complex [Au(2)(Me(2)-form)(2)], 1, (Me(2)-form = 2,6-Me(2)-formamidinate) reacts with Hg(CN)(2) to form a 2D structure, 1.2Hg(CN)(2).2THF. Each gold center interacts with two Hg(CN)(2) molecules. The Au...Au distance increases from 2.7 Angstroms in the starting dinuclear complex to 2.9 Angstroms in the adduct. The gold centers are connected to four nitrogen atoms with Au-N distances in the range 2.13-2.51 Angstroms. The cyanide stretch is shifted from 2192 cm(-1) in the Hg(CN)(2) to 2147 cm(-1) in the adduct.     

Reactions with Hydrazidoyl Halides XII Synthesis of Pyrazolo[5,1-c]-1,2,4-triazine,Selenadiazolo[3,2-a]quinazolones,Selenadiazoline, Thiadiazoline and Thiazole Derivatives

Several new pyrazolo[5,I-c]triazine, selenadiazoline, thiadiazoline, selenadiazolo[3,2-a]quitiazolone, and arylazothiazole derivatives were synthesised by the reaction of hydrazonoyl halides with different reagents. The structure of new heterocycles were assigned on the basis of their elemental analysis, spectral data, and alternate synthesis whenever possible.     

Preparation and characterization of mononuclear nickel(II) and copper(II) complexes of a hexaazamacrobicyclic ligand

Summary The structure of the hexaazamacrobicycle, sarcophagine, (diAMMEsar)·2H₂O, formed by extracting Co ion from the [Co(diAMMEsar H₂)]Cl₅·-H₂O cage with 8-hydroxyquinoline, has been determined by elemental analysis, and i.r., u.v.-vis., ¹H-n.m.r. and mass spectroscopies. Two octahedral complexes, [M(diAMM-EsarH₂)]Cl₄·2H₂O (M = Ni^II or Cu^II), have been prepared and characterized. The e.s.r. spectrum of the Cu^II complex in the solid state indicates spin-exchange interaction between the Cu^II ions. However, in CD₃OD-D₂O (10%) at 77K, the spectrum is characteristic of a compound having axial symmetry (d _x ²−y ²).     

New heterocyclic syntheses from hydrazidoyl halides. Convenient syntheses of fused pyrimidines,pyridazines, and quinazolines

Aminocyanopyrazole derivatives and pyrazolo[2,3-a]quinazolones were obtained in good yields from hydrazidoyl halides and malononitrile. Pyrazolo[3,4-d]pyridazine and pyridazo[4′,5′: 1,2]pyrazolo[1,5-a]quinazoline derivatives were synthesized in quantitative yields by reaction of hydrazine hydrate with 2 and 16 , respectively. A novel ring system, a 3-substituted tetrahydro derivative of 7-oxo-6H,8H-pyridazo[3′,4′,5′-c'd']-pyrazolo[3,4-d]pyrimidine was prepared by reaction of 6 with dimethyl carbonate. Pyrazolo[3,4-d]pyrimidine-4,6-dithiones were obtained in good yields by reaction of 2 with carbon disulfide. The structures of the products were assigned and confirmed on the basis of their elemental analyses, spectral data, and alternate synthesis wherever possible. The structures of the parent fused heterocyclic systems discussed in this work are summarized in Scheme 1 .