Ni(II)chelates of 4,9-dimethyl-5,8-dizadodeca-4,8-diene-2,11-dione-3,10-diphenyl hydrazone and related molecules

Syntheses and structural characterization of Ni(II) chelates of a new series of symmetric and unsymmetric tetradentate linear ligands are described. Preparative routes involve either the direct reaction between a metal complex and arene diazonium diazonium salts or a simple metal incorporation into the independently synthesized ligands. Recent X-ray structure determination of 4,9-dimethyl-5,8-diazadodeca-4,8-diene-2,11-dione-3,10-di(4′-methyl phenyl) hydrazonatonickel(II) complex reveals the geometry around the Ni(II) to be very close to square planar. The expected distortion because of the disposition of bulky aromatic groups on the neighbouring nitrogens is minimized by their projection in the opposite directions from the plane. PMP, IR and electronic spectral data for the complexes are quite in agreement with this structure.

Bromination of Intermolecular Chelate Linkage Isomers of 3-Oximino-4,9-Dimethyl (or 4,7,9-Trimethyl)-5,8-Diazadodeca-4,8-Diene-2,11-Dionato Nickel(II)

The reaction of the title complexes (FIG. 1) with N-bromosuccinimide or bromine in chloroform yields isomeric bromo complexes on substitution of the γ-CH carbon proton by bromine. The brominated products have been characterised by ir, pmr, electronic absorption spectra, conductivity and magnetic susceptibility measurements. The linkage isomerisation of the brominated products in chloroform has been shown to depend on the diamine residue.

Structure of pregna-4,16-diene-7[alpha],14[alpha]-diol-3,20-dione

7a,14a-Dihydroxypregna-4,16-diene-3,20- dione, C21H2804, M r = 344.45, orthorhombic, P212121, a = 7.136 (1), b = 12.342 (1), c = 20.049 (3)/k, V= 1765.7 (3)/k 3, Z = 4, Dx = 1.295 g cm -3, A(Cu Kte) = 1.5418/k, /z = 6.7 cm- a, F(000) = 744, T = 293 K, R = 0.048 for 1345 observations. The A ring may be described as in a l a,2flhalf- chair conformation or a l a-sofa conformation. The B and C rings adopt normal chair conformations and the D ring has a 14a-envelope conforma tion. The molecules are held together by a hydrogen bond [0(3)...0(7)= 2.767 A].

An Enantiospecific Approach to Irregular Ligusticum grayi Sesquiterpenes: Synthesis of cis-Preisothapsa-2,8(12)-diene

Enantiospecific syntheses of 1-epi- (or cis-)-preisothapsa-2,8(12)-diene and 1-epi- and 1,8-diepipreisothapsa-2-en-12-ols, starting from the readily available monoterpene (R)-carvone, have been accomplished.

Synthesis, reactivity and structural characterisation of bicyclic tetraphosphapentazanes

The diphenoxy bicyclic tetraphosphapentazane derivatives (EtN)(5)P-4(OPh)(2) 2 and its monoxide (EtN)(5)P-4(O)(OPh)(2) 3 have been prepared. Both 2 and 3 exist as a mixture of two isomers. One isomer of (EtN)(5)P-4(O)(OPh)(2) 3a has been isolated and its reaction with tetrachloro-1,2-benzoquinone yielded (EtN)(5)P-4(O)(OPh)(2)(O2C6Cl4) 5 in which the junction phosphorus atom becomes five-co-ordinated. Treatment of 2 or 3a with [Mo(CO)(4)(nbd)] (nbd = norbornadiene, bicyclo[2.2.1]hepta-2,5-diene), on the other hand, yielded the chelate complex [Mo(CO)(4){(EtN)(5)P-4(O)(n)(OPh)(2)}] (n = 0 or 1; 6 or 7) in which the peripheral phosphorus atoms are bonded to the metal. The structures of 3a and 5-7 have been confirmed by single-crystal X-ray diffraction studies. The two P3N3 rings in 3a and 5 adopt twist/twist and irregular/twist conformations respectively; the phenoxy substituents occupy the 'pseudo axial' positions. However, an ideal chair conformation is observed for the P3N3 rings in 6 and 7 with the phenoxy substituents taking up the 'pseudo equatorial' positions. The NMR spectroscopic data for the compounds are discussed.

Mode of Coordination and Chemical Reactivity of Alpha-Imine Hydrasone Ligands

Interaction of nickel(I1) and copper(I1) complexes of 4,9-dimethy1-5,8-diazadodeca-4,8diene-2,1 ldione, Ni(baen) and 4,6,9-trimethyl-5, 8diazadodeca-4,8-diene-2,ll-dione, Ni(bapn), with arene diazonium chlorides in buffered solutions of methanol yielded metal derivatives of glyoxaliminearylhydrazones. This typical electrophilic addition at the 3-carbon of the complex occurs owing to the pseudo aromatic behaviour of the chelate ring. A mechanism which predicts the attack of the diazonium cation through the coordination shell of the metal is well documented from the available experimental evidences. The chemical reactivity of a few complexes with a single residual non-substituted y-carbon is reasonably manifested by their reaction with phenyl isocyanate.

Synthesis of Azo Coupled Crown Ethers Containing Transition Metal and other Chromophoric Environments and Their Ion Complexation Properties

The crown ethers, 2,3-benzo-1,4,7,10,13-pentaoxa-cyclopentadeca-2-ene and 2,3, ll,12-dibenzo-l,4,7,10,13,16-hexaoxscyclooctadeca-2,11-diene are incorporated into H,N'-ethylenebis(acetylacetoneimino) nickel(II) and copper(II), phenol, and β-naphthol by diazo coupling reactions. The selective nature of the coupling reaction has-been demonstrated by the isolation of both asymmetric mono- and symmetric bis(glyoxalarylcrownhydrazoneimino) metal(II) complexes. An interesting binuclear complex containing two intramolecularly rearranged (glyoxal-hydrazonearylimino) metal(II) groups joined by 18-crown-6 result8 when bis(arenediazonium)-18-crown-6 is coupled with the metal(I1) Schiff bases. The substituted ethers form cationic salts with NaClO4, KCNS, NH4CNS, 14g(CNS)2 and Ca(CNS)2. All the synthesised ethers exhibit ion selectivity sequence as K+ > Na+ and Ca2+ > Mg2+.

Heterocyclic steroidsâVII *1: Rearrangement of 1-diethylamino-5-(m-methoxyphenoxy)-pent-2-yne

Thermal rearrangement of diethylamino 5-(m-methoxyphenoxy)-pent-2-yne (3) gives 1-(m-methexyphenoxy)-pent-3,4-diene (14) in about 8% yield. Hydration of the latter yields 1-(m-methoxyphenoxy)-pentan-4-one (6), which has been synthesised by an unambiguous route. A mechanism of formation of the allene (14) from the amine (3) has been suggested.

Synthesis of Azo Coupled Crown Ethers Containing Transition Metal and other Chromophoric Environments and Their Ion Complexation Properties

The crown ethers, 2,3-benzo-1,4,7,10,13-pentaoxa-cyclopentadeca-2-ene and 2,3, ll,12-dibenzo-l,4,7,10,13,16-hexaoxscyclooctadeca-2,11-diene are incorporated into H,N'-ethylenebis(acetylacetoneimino) nickel(II) and copper(II), phenol, and β-naphthol by diazo coupling reactions. The selective nature of the coupling reaction has-been demonstrated by the isolation of both asymmetric mono- and symmetric bis(glyoxalarylcrownhydrazoneimino) metal(II) complexes. An interesting binuclear complex containing two intramolecularly rearranged (glyoxal-hydrazonearylimino) metal(II) groups joined by 18-crown-6 result8 when bis(arenediazonium)-18-crown-6 is coupled with the metal(I1) Schiff bases. The substituted ethers form cationic salts with NaClO4, KCNS, NH4CNS, 14g(CNS)2 and Ca(CNS)2. All the synthesised ethers exhibit ion selectivity sequence as K+ > Na+ and Ca2+ > Mg2+.

Heterocyclic Steroids .7. Rearrangement Of 1-Diethylamino-5-(Met-Methoxyphenoxy)-Pent-2-Yne

Thermal rearrangement of diethylamino5-(m methoxyphenoxy)-pent-2-yne (3) gives 1-(m-methexyphenoxy)-pent-3,4-diene (14) in about 8% yield. Hydration of the latter yields 1-(m-methoxyphenoxy)-pentan-4-one (6), which has been synthesised by an unambiguous route. A mechanism of formation of the allene (14) from the amine (3) has been suggested.

Studies on ß-arylhydrazone-imine nickel(II) complexes—Examples of metal template syntheses

ß-arylhydrazone-imine ligand complexes of nickel(II), namely, 4,10-dimethyl-5,9-diazatrideca-4,9-diene-2,12-dione-3,11-diphenylhydrazonato nickel(II), Ni(acacpn)(N2Ph-R)2 and 1,11-diphenyl-3,9-dimethyl-4,8-diazaun-deca-3,8-diene,1,11-dione-2,10-diphenyl hydrazonato nickel(II), Ni (beacpn) (N2Ph-R)2, [R = H, o-CH3p-CH3] have been prepared by metal template reactions and characterized. Both the azomethine nitrogens and α-nitrogens of bis-hydrazone form the coordination sites of the square-planar geometry around the nickel(II) ion. Loss of CO from the molecule and subsequently an interesting methyl group migration to the nucleus of the chelate ring have been observed in the mass spectrum. Structures are proposed based on the spectral and magnetic properties.

A biomimetic total synthesis of allomicrophyllone: protective Diels-Alder reaction as a stratagem

A biomimetic total synthesis of bioactive tetracyclic natural product allomicrophyllone has been achieved in which a protective Diels-Alder reaction employing a disposable sacrificial 1,3-diene directs the regioselectivity of the subsequent Dials-Alder reaction. (C) 2010 Elsevier Ltd. All rights reserved.