On the conformations of isomeric trimethyl -methylcyclohexane-1,2,3-tricarboxylates

A study has been made of the stereochemistry of three of the four possible configurational isomers of trimethyl 1-methylcyclohexane-1,2,3-tricarboxylate. Two of the isomers undergo highly stereoselective methylation at the 3-position; the third cannot be methylated under similar conditions. Conformations have been suggested for these three isomers on the basis of n.m.r. results. It is thought that axial ester groups at the 1-position in the first two solvate the axial protons at the 3-position and facilitate their removal by trityl anion, while in the third, which has an axial methyl at the 1-position, the effect is not possible and the anion is not formed. The role of A(1.3) strain in causing the high stereoselectivity and position-specificity in the two cases where alkylation does take place and the reasons for slow inversion at the anion centre at position 3 in one of them are discussed.

Azulenes and related substances—XII *1, , *2: A new azulene synthesis—guaiazulene and Se-Guaiazulene

The new method of azulene synthesis, described in the preceding communication, has been extended to the synthesis of guaiazulene and Se-guaiazulene.

4-(5-Phenyl-1,2,4-triazolo[3,4-a]isoquinolin--yl)benzonitrile

In the title molecule, C23H14N4, the triazoloisoquinoline ring system is nearly planar, with an r.m.s. deviation of 0.038 (2) angstrom and a maximum deviation of -0.030 (2) angstrom from the mean plane of the triazole ring C atom which is bonded to the benzene ring. The benzene and phenyl rings are twisted by 57.65 (8) and 53.60 (9)degrees, respectively, with respect to the mean plane of the triazoloisoquinoline ring system. In the crystal structure, molecules are linked by weak aromatic pi-pi interactions [centroid-centroid distance = 3.8074 (12) angstrom]. In addition, the crystal structure exhibits a nonclassical intermolecular C-H center dot center dot center dot N hydrogen bond.

3-(4-Chlorophenyl)-5-phenyl-1,2,4-triazolo[3,4-a]isoquinoline

In the title molecule, C22H14ClN3, the triazoloisoquinoline ring system is approximately planar, with an r.m.s. deviation of 0.033 (2) angstrom and a maximum departure from the mean plane of 0.062 (1) angstrom for the triazole ring C atom, bonded to the benzene ring. The benzene and phenyl rings are twisted by 57.02 (6) and 62.16 (6)degrees, respectively, to the mean plane of the triazoloisoquinoline ring system. The molecule is stabilized by a weak intramolecular pi-pi interaction [centroid-centroid distance = 3.7089 (10) angstrom] between the benzene and phenyl rings. In the crystal structure, weak intermolecular C-H center dot center dot center dot N hydrogen bonds and C-H center dot center dot center dot pi interactions link the molecules.

(2E)-3-(4-Bromophenyl)-1-(2-methyl-4phenyl-3-quinolyl)prop-2-en-1-one

The conformation about the ethene bond [1.316 (3) angstrom] in the title compound, C25H18BrNO, is E. The quinoline ring forms dihedral angles of 67.21 (10) and 71.68 (10)degrees with the benzene and bromo-substituted benzene rings, respectively. High-lighting the non-planar arrangement of aromatic rings, the dihedral angle formed between the benzene rings is 58.57 (12)degrees.

1-[(2-Chloro-3-quinolyl)methyl]indoline-2,3-dione

In the title compound, C18H11ClN2O2, the isatin and 2-chloro-3-methylquinoline units are both almost planar, with r.m.s.deviations of 0.0075 and 0.0086 angstrom, respectively, and the dihedral angle between the mean planes of the two units is 83.13 (7)degrees. In the crystal, a weak intermolecular C-H center dot center dot center dot O interaction links the molecules into chains along the c axis.

Reactions of tetrahalogeno-1,2-benzoquinones. Part III. Reaction of tetrachloro-1,2-benzoquinone with tetralones and naphthols: Pathway to the condensates

With a view to understanding the mechanism of the formation of 6-methoxy-2,2-(tetrachloro--phenylenedioxy)-naphthalen-1 (2H)-one (IIIa) in the reaction of 6-methoxy-1-tetralone (Ia) with tetrachloro-1,2-benzoquinone (II), the reaction of (II) with various tetralones and naphthols has been studied. Reaction with either α-tetralone or α-naphthol gives 2,2-(tetrachloro-o-phenylenedioxy)naphthalen-1 (2H)-one (IIIb), whereas reaction with either β-tetralone or β-naphthol gives a mixture of (IIIb) and ,1-(tetrachloro-o-phenylenedioxy)-naphthalen-2 (1H)-one (IX), with the former predominating. Further, reactions of (II) with 7-methoxy-3,4-dihydrophenanthren- 1 (2H)-one and m-methoxyphenol gave respectively 7-methoxy- ,2-(tetrachloro-o- phenylenedioxy)phenanthren-1 (2H)-one (VII) and 3-methoxy-6,6-(tetrachloro-o- phenylenedioxy)cyclohexa-2,4-dien-1-one (VIII). Structures of all these compounds have been proved on the basis of i.r. and n.m.r. data. The pathway to the formation of the condensates (III) is discussed.

Cu(II) complexes of 1-benzyl-2-phenyl-benzimidazole

Copper(II) complexes of 1-benzyl-2-phenylbenzimidazole (BPBI) of the general formula Cu(BPBI)2X2, nH2O [X= Cl-, Br-, NO3 or OAc- (n = O) and X = NO3- or 1 2SO42-(n = 2H2O)] have been prepared. The complexes are found to be nonelectrolytes in nitrobenzene. Conductivity in nonaqueous media, magnetic susceptibilities and i.r. and electronic spectra of the complexes are reported. A tetragonally distorted octahedral structure has been suggested for these complexes.

Indoleacetaldoxime hydro-lyase (4.2.1.29). III. Further studies on the nature and mode of action of the enzyme

Further purification of indoleacetaldoxime (IAOX) hydro-lyase from Gibberella fujikuroi by DEAE-cellulose chromatography is described. The purified enzyme was activated by dehydroascorbic acid (DHA), ascorbic acid (AA), and pyridoxal phosphate (PALP) and was inhibited by thiol compounds and thiol reagents including phenylthiocyanate. Ferrous ions but not ferric ions activated the purified enzyme. The enzyme was activated by dihydrofolic acid but inhibited by tetrahydrofolic acid. Phenylacetaldoxime, a competitive inhibitor, afforded partial protection of the enzyme from the action of N-ethylmaleimide suggesting the involvement of a thiol function at the active site or substrate-binding site. The inhibition of the enzyme by 2,3-dimercaptopropanol was reversed by DHA, PALP, or frozen storage. KCN inhibition of the enzyme was reversed by PALP. NaBH4 reduction of the purified enzyme in the presence of PALP gave an active enzyme which was further activated by PALP or DHA but not by ferrous ions. These results suggested a "structural" role for PALP in the activity of IAOX hydro-lyase. Dilute solutions of the purified enzyme, obtained during DEAE-cellulose chromatography and concentrated using sucrose, showed enhanced activity upon frozen storage and thawing. The increase in activity of the enzyme during certain culture conditions, the activation and inhibition of the enzyme by several unrelated compounds, and the effect of freezing indicate that IAOX hydro-lyase is probably a metabolically regulated enzyme with a structure composed of subunits.

Transition metal complexes of 3-aryl-2-substituted 1,2-dihydroquinazolin-4(3H)-one derivatives: New class of analgesic and anti-inflammatory agents

Five-coordinate, neutral transition metal complexes of newly designed pyridine-2-ethyl-(3-carboxyhdeneamino)-3-(2-phenyl)-1,2-dihydroquinazoli n-4(3H)-one (L) were synthesized and characterized The structure of ligand is confirmed by single crystal X-ray diffraction studies The compounds were evaluated for the anti-inflammatory activity by carrageenan-induced rat paw edema model while their analgesic activity was determined by acetic acid-induced writhing test in mice wherein the transition metal complexes were found to be more active than the free ligand (C) 2010 Elsevier Masson SAS All rights reserved.

Synthesis of the lactone of 2-carboxy-4-hydroxy-7-methoxy-1, 2, 3, 4-tetrahydrophenanthrone

Starting from 6-methoxynaphthaldehyde-2, 2-carboxy-7-methoxy-1, 2, 3, 4-tetrahydrophenanthrone-4 was prepared. Sodium borohydride reduction of the keto-acid followed by chromic acid oxidation yielded the lactone of 2-carboxy-4-hydroxy-7-methoxy-1, 2, 3, 4-tetrahydrophenanthrone. Alkylation of the lactone of 2-carboxy-4-hydroxy-6-methoxytetralone was not promising.

Synthesis of 1,3-dimethyl-1,3-dicarboxycyclohexane-2-acetic acid. An isomer of the degradation product of abietic acid

A synthesis of 1,3-dimethyl-1,3-dicarboxycyclohexane-2-acetic acid has been described, and proved to be an isomer of the C12-acid-an oxidative degradation product of abietic acid.

Isomerisations of substituted β-keto-esters - Part II. Isomerisation of ethyl 1-ethoxycarbonyl 2oxocyclopentyl acetate into 2, 3-diethoxycarbonylcyclohexanone

A mechanism for the isomerisation of ethyl 1-ethoxycarbonyl-2-oxocyclopentylacetate (I) into a cyclohexane β-keto-ester as proceeding through an intermediate bicyclic /gb-diketone (VII) has been considered as an alternative mechanism to one earlier suggested.1 The determination of the structure of the isomerised β-keto-ester as 2, 3-diethoxycarbonylcyclohexanone (V) has provided support for the earlier mechanism.