Synthesis of thiadiazoles,triazoles and oxadiazoles from sulfonyl acetic acids via a common route

A new class of five membered heterocycles, thiadiazoles, triazoles and oxadiazoles were prepared from sulfonyl acetic acids via acid hydrazides.     

Densities,Ultrasonic Speeds,Viscosities and Refractive Indices of Binary Mixtures of Benzene with Benzyl Alcohol,Benzonitrile, Benzoyl Chloride and Chlorobenzene at 303.15 K

Densities,ρ, ultrasonic speeds, u, viscosities,η, and refractive indices, n, of pure benzene, benzyl alcohol (BA), benzonitrile (BN), benzoyl chloride (BC), chlorobenzene (CB) and their thirty six binary mixtures, with benzene as common component, were measured at 303.15 K over the entire mole fraction range. From these experimental data the values of deviations in ultrasonic speed, △u, isentropic compressibility, △k_s,excess acoustic impedance, Z^E, deviation in viscosity, Dh, and excess Gibbs free energy of activation of viscous flow, G^*E, and partial molar isentropic compressibility, Kφ,2⁰ of BA, BN, BC and CB in benzene were computed. The variation of these derived functions with composition of the mixtures suggested the increased cohesion (molecular order) in the solution and that interaction (A-B)＞(A-A) or (B-B).Moreover, theoretical prediction of ultrasonic speed, viscosity and refractive index of all the four binary mixtures was made on the basis of empirical and semi-empirical relations by using the experimental values of the pure components. Comparison of theoretical results with the experimental values was made in order to assess the suitability of these relations in reproducing the experimental values of u, η and n. Also, molecular radii of pure liquids and the average molecular radii of binary mixtures were evaluated using the corresponding refractive indices of pure liquids and binary mixtures. The average molecular radii of binary mixtures were found to be additive with respect to mole fraction of the pure component.     

Synthesis,structural and biochemical aspects of titanocene and zirconocene chelates of acetylferrocenyl thiosemicarbazones

The reactions of bis(cyclopentadienyl)titanium(IV)/zirconium(IV) dichloride with a new class of organometallic thiosemicarbazones (LH), derived by condensing acetylferrocene with substituted thiosemicarbazides, have been studied and two types of bimetallic products, viz. [Cp₂M(L)Cl] (M = Ti or Zr) and [CpZr(L)₃], have been isolated. On the basis of various physicochemical and spectral studies, five- and seven-coordinate structures have been assigned to these derivatives, respectively. Attempts have been made to establish a correlation between biological activity and the structures of the products.     

Reaction of sulphate radical anion (SO<Superscript>.</Superscript><Subscript>4</Subscript><Superscript>-</Superscript>) with hydroxy-and methyl-substituted pyrimidines: a pulse radiolysis study

Reactions of sulphate radical anion (SO·₄ ^-) with 4,6-dihydroxy-2-methyl pyrimidine (DHMP), 2,4-dimethyl-6-hydroxy pyrimidine (DMHP), 6-methyl uracil (MU) and 5,6-dimethyl uracil (DMU) have been studied by pulse radiolysis at pH 3 and at pH 10. The transient intermediate spectra were compared with those from the reaction of hydroxyl radical (·OH). It is proposed that SO·₄ ^- produces radical cations of these pyrimidines in the initial stage. These radical cations are short-lived except in the case of DMHP where a relatively longer lived radical cation is proposed to be formed. When there is a hydrogen atom attached to the N(1) or N(3) position, a deprotonation from these sites is highly favored. When there is no hydrogen attached to these sites, deprotonation from a substituted methyl group is favored. At acidic pH, deprotonation from nitrogen is observed for DHMP, MU and DMU. At basic pH, the radical cation reacts with OH^- leading to the formation of OH adducts.     

A novel three-component reaction for the diastereoselective synthesis of 2H-pyrimido[2,1-a]isoquinolines via 1,4-dipolar cycloaddition

[reaction: see text] The 1,4-dipole derived from isoquinoline and DMAD has been shown to react readily with N-tosylimines resulting in the diastereoselective synthesis of 2H-pyrimido[2,1-a]isoquinoline derivatives.     

Iron(III) complexes of a tetradentate tripodal ligand N,N′,N″-tris (2-benzimidazolyl-methyl)amine

Summary Fe^III complexes of a tetradentate ligand with pendant benzimidazolyl groups have been synthesized and characterized. Room temperature Mössbauer spectra depict a quadruple split doublet in the case of NO _inf3 ^p– as co-ligand, while a nearly symmetrical one line spectrum is obtained for complexes with Cl^–as co-ligand. The isomer shift values are towards the lower end of the range found for other high spin Fe^III complexes. ¹H-n.m.r. spectra of the complexes reveal relatively broad linewidths with large isotropic shifts. Paramagnetically shifted resonances are observed in the range of –10.0–+70.0 p.p.m.Author to whom all correspondence should be directed.     

Stereospecific route to 5,11-methanomorphanthridine alkaloids via intramolecular 1,3-dipolar cycloaddition of nonstabilized azomethine ylide: formal total synthesis of (+/-)-pancracine

The core structure of the complex pentacyclic 5,11-methanomorphanthridine alkaloids is constructed stereospecifically in one step employing an intramolecular [3 + 2]-cycloaddition of nonstabilized azomethine ylide as the key step. The strategy is demonstrated by accomplishing the formal total synthesis of (+/-)-pancracine. [reaction: see text]     

Nonradiative energy transfer from Tb3+ → Er3+ in calibo glass

Energy transfer studies have been made in a terbium-erbium coactivated calibo-glass system at room temperature and at liquid-air temperature. A study of the emission and decay of ⁵D₄ level of Tb³⁺ has been made by varying the acceptor (Er³⁺) concentration. Probabilities and efficiencies of energy transfer as well as donor-acceptor distances have been calculated. At low acceptor concentration the decay of the donor (Tb³⁺) emission has been found to be diffusion limited. At high acceptor concentration the mechanism governing the transfer is found to be dipole-dipole.     

Electron impact induced fragmentation of some 1,2,4-triazole derivatives

The mass spectra of eight 1,2,4-triazole derivaties have been recorded and found tao reveal extensive hydrogen and skeletal migrations. The structures of the fragments have been confirmed by deuterium labelling and exact mass measurement. The compounds revealed striking differences in their spectra depending on the nature of the substituents.