Journal of Chemical Research

Recent work on the syntheses, structures and properties of complexes of polydentate and macrocyclic thio- and seleno-ether ligands with Groups 3-6 metals in positive oxidation states (≥3) is described.

Novel spiro 1,3-benzoxazine dimers are obtained when hydrazones of 2-hydroxyacetophenone are treated with triphosgene. An X-ray crystal structure, and the NMR and mass spectra of these new compounds, are reported and discussed.

Distributions of rearrangement products from a dihydrobenzhomobarrelene and the analogous benzyhomobarrelene are different. Isomeric alkenes 18 and 20 have been synthesised.

X-ray analysis of Ni(II) complexes of the self-assembling system LH₂, [pyda.H₂][pydc] (pydc.H₂ = 2,6-pyridinedicarboxylic acid and pyda = 2,6-pyridinediamine), indicated that two six-coordinated anionic [pyda.H]₂[Ni(pydc)₂].H₂O (I) and neutral [Ni(pydc.H)₂].3H₂O (II) complexes are formed at different temperature conditions in water; in agreement with the results obtained from potentiometric pH titrations in the pH range 3.5–5.5.

From the leaves of Viburnum cotinifolium, a new biflavonoid named as I-5, II-5, I-7, II-7, I-4’, II-4′-hexahydroxy [6-O-8] biflavone along with seven known flavonoids have been isolated. Their structures were elucidated from their chemical and physical data (IR, UV, ¹H NMR, ¹³C NMR and mass spectra).

Suzuki reactions have been used successfully to effect cross-coupling of 5-halopyrimidines with 4-chlorobenzeneboronic acid and 2,4-diamino-5-(4-chloro-3-halo)-6-ethylpyrimidines with 4-methoxybenzeneboronic acid. The antimalarial drug pyrimethamine has been prepared by coupling 2,4-diamino-6-ethyl-5-iodopyrimidine with 4-chlorobenzeneboronic acid.

Calculations using the MNDO-PM3 method were performed to elucidate the mechanism of stereoselective base-catalyzed reaction affording exclusively (Z)-2-alkylidene-4-oxothiazolidine push-pull derivatives from the corresponding α-mercapto esters and activated β-oxonitriles in ethanol as a solvent.

A facile synthetic route for 5-aryl[1,2,4]triazolo[1,5-c]quinazolin-2(3H)-ones and 2(3H)-thiones (3, 4) via 3,1-benzoxazin-4(3H)-ones in good yields under anhydrous conditions has been devised in an effort to develop new bronchodilators for the treatment of asthma.

A novel 2-D Ag^I neutral infinite framework of a large delocalised system diquinoxalino[2,3-a:2′,3′-c]phenazine (L), [Ag_2.5L(NO₃)_2.5]∞ (1), has been synthesised and structurally determined, in which three kinds of different coordination modes are found for the Ag^I centers.

A novel tridentate ligand C₅H₄NCONHCOC₅H₄N (HL) has been formed by Cannizzaro type reaction of pyridine-2-carboxaldehyde and NaNCO in the presence of copper metal ion and its mononuclear distorted square pyramidal complex [Cu(L)(NCO)(H₂O)], 1 has been synthesised and characterised.

The catalyst composed η⁵-C₅H₄(CPh₃)TiCl₃ with methylaluminoxane showed catalytic activity for stereo specific polymerisations of styrene and 1,3-butadiene

A combination of dimethylsilylene-bridged bis-cyclopentadienyltitanium dichloride and methylaluminoxane showed high catalytic performance toward the polymerisation of 1,3-butadine.

Novel steroids are obtained by reaction of 9,11-dehydro-dibenzylestradiol and dibenzylestradiol with phenyllithium in THF at room temperature.

2,6-Dicarboxypyridinium chlorochromate can be used as a rapid, mild and efficient reagent for oxidation of alcohols, silyl ethers and THP ethers to their carbonyl compounds.

4,7-Bis(2-thienylethynyl)-2,1,3-benzothiadiazole was prepared by Sonogashira coupling. The crystal structure showed that one thiophene ring is coplanar and the other is perpendicular to the benzothiadiazole ring.

Polystyrene-bound phenylseleninic acid was prepared conveniently and aldehydes were catalytically oxidised to carboxylic acids with hydrogen peroxide using this polymer as catalyst.

The synthesis of two novel quinone methides (4a and 4b) containing tricyclic heterocyclic systems with 7-membered central rings has been achieved in good yields under relatively mild reaction conditions.

A method was developed to quench the effect of pH on the determination of octan-1-ol / water partition coefficients (k_ow) of p-benzo- and p-naphthoquinones by using a mildly buffered aqueous phase.

In this work, the thermodynamics of some other cobalt (III) Schiff base complexes with different ligands and the solvent effect have been examined. Comparison of their properties, spectrally and thermodynamically, aimed to investigate the effects of different electronic and steric situations.

The preparation of methoxy and cyanonaphthalene derivatives is described. The preparation of 1,3-dimethoxynaphthalene, 1-bromo-3-methoxynaphthalene, 1-methoxy-3-bromonaphthalene and 1,3-dicyanonaphthalene involves the reaction of 1,3-dibromonaphthalene with the corresponding nucleophile.