bluuebunny/crossref_metadata_2025 huggingface dataset:
Production and Characterization of Beams of Polystyrene Ions
Authors: Craig AG , Derrick PJ
Published: September 2010

The formation of gaseous polystyrene molecular ions [M]+ by means of the technique of field desorption is proposed to involve creation of a charged sample/gas interface and subsequent field evaporation of ions. The molecular ions so formed fragment spontaneously in the gas phase, provided the emitter temperature is sufficiently high. The polystyrene chains rupture near their ends rather than in their centres, which is proposed to be a consequence of efficient charge delocalization. Following collisional activation, the polystyrene chains break up to give low-mass fragment ions. The low-mass fragment ions are proposed to be the result of successive depolymerization steps, following initial direct bond cleavage within the polymer chain.
New Insights Into the Electronic-Structures of Solid-State Dioxygen Adducts of N,N′-Ethylenebis(Salicylaldiminato)Cobalt(II), Co(Salen), and of Active Precursors
Authors: Murray KS , Vandenbergen A , Kennedy BJ , West BO
Published: September 2010

Oxygen-active forms of [Co( salen )], derived from solvated forms such as [Co( salen )].C6H6, [Co( salen )]CHCl3 and Co( salen )(C5H5N), have long been known to bind dioxygen reversibly in the solid state. It has generally been accepted that the product of oxygenation is the diamagnetic peroxo -bridged species [Co( salen )]2O2. However, the present detailed study of temperature-dependent magnetic susceptibilities and of electron spin resonance spectra clearly shows that this is an oversimplification. The data show that the oxygenated species also contain the paramagnetic superoxo -like species [O2Co( salen )] as well as dimeric 'inactive' [Co( salen )]2 centres . Prolonged oxygenation produces also a second monomeric Co(salen) component although the e.s.r . spectra of both CoIIspecies are diminished in intensity relative to the [O2Co( salen )] signal. The magnetic properties of the oxygen-active Co( salen ) samples are compatible with ferromagnetically coupled pairs of Co( salen ) molecules, with further weak antiferromagnetic coupling between such sets of pairs. These magnetostructural features appear to be related to the solid-state oxygen reactivity. The solvated precursors also show weak magnetic interactions but different in detail to those in the desolvated materials.
Divalent Metal-Complexes of 2-Fluorophenoxyacetic Acid - the Crystal-Structures of 2-Fluorophenoxyacetic Acid, Tetraaquabis(2-Fluorophenoxyacetato)Zinc(II) Dihydrate and Aquabis(2-Fluorophenoxyacetato)Bis(Pyridine)Copper(II)
Authors: Kennard CHL , Oreilly EJ , Schiller S , Smith G , White AH
Published: September 2010

The crystal structures of
2-fluorophenoxyacetic acid ( oflpaH ) and the metal
complexes aquabis (2-fluorophenoxyacetato) bis (pyridine)copper(II) (1) and tetraaquabis (2-fluorophenoxyacetato)zinc(II)
dihydrate (2) have been determined by X-ray
diffraction and refined to residuals R 0.036, 0.041, 0.025 for 641, 863 and
1505 observed reflections respectively. The acid crystallizes in a monoclinic
cell, space group P21/c with a 6.207(2), b 19.363(8), c 6.999(2)
Ǻ, β 114.81(2)� and Z 4. The molecules form planar, centrosymmetric , hydrogen-bonded cyclic dimers
[O...O, 2.618(4)Ǻ]. Complex (1) is orthorhombic, space group P2cb with two
molecules in a cell of dimensions a 5.621 (2), b 17.218(7), c 13.288(6)Ǻ
while (2) is monoclinic, space group P21/c, a 6.597(2), b 5.279(2),
c 30.079(10) Ǻ, β 94.65(3)�; with Z 2. Complex (1) has
square-pyramidal geometry with the basal plane containing two trans related
carboxyl oxygens [Cu-O, 1.944(4)Ǻ] and two trans
related pyridine nitrogens [Cu-N, 2.030(5)Ǻ]. A
water molecule occupies the apex of the square pyramid [Cu-OW,
2.199(8)Ǻ]. Complex (2) has octahedral geometry with the MO6
octahedron containing two trans related carboxyl oxygens
[Zn-O, 2.122(2)Ǻ] and four water oxygens [Zn-OW,
2.069(2), 2.085(2)Ǻ]. Preliminary X-ray data also confirm that the
magnesium(II) and manganese(II) complexes of 2-fluorophenoxyacetic acid are isomorphous with (2) but different from the cobalt(II)
derivative.
An ab initio Investigation of the Equilibrium Structures of Hydrazine and of the Transition Structures Connecting Them
Authors: Riggs NV , Radom L
Published: September 2010

An ab initio investigation of the various equilibrium and transition structures of hydrazine has been carried out with full geometry optimization and use of the 3-21G, 3-21G(N*), and 6-31G* basis sets. Best estimates of relative energies (as quoted below) were obtained by evaluation of total electronic energies at the MP3/6-31G**//6-31G* level. By vibrational analysis, it was confirmed that the gauche form is an equilibrium species and that the syn form, which lies 39.8 kJ mol-1 above the gauche form, is a transition structure connecting enantiomeric gauche forms by internal rotation. The anti form, characterized by vibrational analysis as an equilibrium species on the STO-3G, 3-21G, and 6-31G* potential-energy surfaces, lies in a shallow minimum 7.7 kJ mol-1 above the gauche form. A transition structure connecting gauche and anti forms by internal rotation lies, however, only 0.4 kJ mol-1 higher on the electronic-energy surface and, after zero-point vibrational -energy corrections, 0.3 kJ mol-1 below the anti form which is, therefore, the true transition structure. The transition structure for inversion at one nitrogen atom of the gauche form is shown to be a CS structure lying 26.2 kJ mol-1 above the gauche form itself. Various other structures, including those of D2h and D2d symmetry, are discussed briefly and shown by vibrational analysis to be neither equilibrium species nor true transition structures on the 3-21G potential-energy surface. Finally, the complete potential function for internal rotation has been evaluated at levels up to MP3/6-31G**//HF/6- 31G*, and the coefficients of the corresponding four-term Fourier cosine series are presented and briefly discussed.
Lewis-Base Adducts of Group 11 Metal(I) Compounds. XXV. Synthesis and Structural Properties of Tris(Triphenylphosphine)Copper(I) Perchlorate and Nitrate
Authors: Dyason JC , Engelhardt LM , Healy PC , Klich HL , White AH
Published: September 2010

The compounds (PPh3)3CuOClO3 and (PPh3)3CuONO2(as its mono-ethanol solvate) have been characterized by single-crystal structure analysis. Crystals of the perchlorate are trigonal , P3, a 18.748(8), c 11.731(6)Ǻ, Z 3, and are isomorphous with the chloride and tetrafluoroborate structures. R was 0.062 for No = 1452 independent 'observed' reflections. Cu-P distances are 2.314(5), 2.313(7) and 2.317(8)Ǻ for each of the three molecules in the unit cell. P-Cu-P angles are 114.5(3), 114.4(3) and 115.6(3)°; Cu-O are 2.32(3), 2.23(3) and 2.23(3)Ǻ. Crystals of the nitrate are monoclinic, P21/n, a 14.875(5), b 23.349(7), c 14.141(7) Ǻ, β 91.73(3)°, Z 4. R was 0.045 for No = 4066. Cu-P distances are 2.312(2), 2.337(2) and 2.339(2)Ǻ; P- Cu-P angles are 114.15(7), 121.37(6) and 113.42(6)°. The nitrate group is monodentate with Cu-O, 2.174(4)Ǻ and Cu-O-N, 124.8(4)°.
Ammonia in the Ion-Source. III. Clustering With N-Oxides, Sulfoxides and Sulfones
Authors: Gillis RG
Published: September 2010

Under positive ion chemical ionization conditions, with ammonia as reagent gas at relatively low pressure, N-oxides, sulfoxides and sulfones form clusters with a proton and one or more ammonia molecules; these clusters can be represented as [M+H]+, [M+NH4]+, [M+N2H7]+, [2M+H]+ and [2M+NH4]+. The unimolecular decomposition of the clusters can be followed by the accompanying metastable peaks.
The Surface Oxidation of Cobaltite
Authors: Buckley AN
Published: September 2010

The oxidation of cobaltite, CoAsS, has been investigated by X-ray photoelectron spectroscopy. Products of the initial oxidation in air were deduced from surfaces abraded under liquid nitrogen rather than fracture surfaces, as fracture of the mineral sample studied took place preferentially along interfaces at which oxidized material was already present. Cobalt and arsenic oxides are formed in air under ambient conditions; however, sulfur is not involved in the initial oxidation. In air-saturated dilute acid, an oxidized layer is retained at the surface of cobaltite ore particles. Under similar aqueous conditions, pyrite, from which cobaltite often has to be separated, remains free of hydrophilic species.
An Alternative Route to 2-Bromo-Estradiols and 2-Iodo-Estradiols From Estradiol
Authors: Pert DJ , Ridley DD
Published: September 2010

Through careful choice of reaction conditions, alkylation of estradiol with chloromethyl methyl ether may yield either the 3,17β-bis(methoxymethy1) ether or the 3-methoxymethyl ether derivative. Treatment of either of these protected estradiols with s- butyllithium, then with trimethylsilyl chloride affords, regioselectively, the 2-trimethylsilyl derivatives which can conveniently be converted into 2-bromo-or 2-iodo-estradiol.
Synthesis and Autoxidation of 2,3,4-Trimethylnaphthalen-1-ol and Related Naphthalen-1-ols
Authors: Greenland H , Pinhey JT , Sternhell S
Published: September 2010

The oxidation of 2-methylnaphthalene, 1,2-dimethylnaphthalene, 2,3-dimethylnaphthalene, and 1,2,3-trimethylnaphthalene by lead tetraacetate in dichloroacetic acid and chloroform gave fair to low yields of the dichloroacetyl derivatives of 2-methylnaphthalen-1-ol, 3,4-dimethylnaphthalen-1-ol, 2,3-dimethylnaphthalen-1-ol, and 2,3,4-trimethylnaphthalen-1-ol respectively. In the case of 1,3-dimethylnaphthalene, dichloroacetoxylation was not observed, and the only isolated product was the binaphthyl (10). 2,3,4-Trimethylnaphthalen-1-ol, obtained on hydrolysis of the dichloroacetyl derivative, was very sensitive to oxygen even in the solid state, and when shaken in chloroform in an oxygen atmosphere gave 4-hydroperoxy-2,3,4-trimethylnaphthalen-l-(4H)-one (14). A study of the autoxidation of the naphthalen-1-ols (7), (19) and (20) led to the conclusion that the oxygen-sensitivity of (11) resulted from a 4,5 peri interaction.
Two Epimeric Dibromo Nitriles From the Australian Sponge Aplysina laevis
Authors: Capon RJ , Macleod JK
Published: September 2010

Two dibromo nitriles, (1′R,5′S,6′S)-2-(3′,5′-dibromo-1′,6′-dihydroxy-4′-oxocyclohex-2′- enyl) acetonitrile (5) and the (l′R,5′R,6′S) epimer (6), possessing antimicrobial activity, have been isolated from the sponge Aplysina laevis (Carter). Cometabolites (+)-aeroplysinin-1 (1) and the dibromo ketone (2) were also identified. Structures (5) and (6) were assigned on the basis of spectroscopic evidence and synthesis from (1).
Oxidation of Alkyl 1,6-Dihydroorsellinates. A New Method for the Synthesis of Methyl Orsellinate and Homologs
Authors: Dyke HJ , Elix JA , Marcuccio SM , Whitton AA
Published: September 2010

An efficient new procedure has been developed for the oxidation of the title compounds, utilizing one mole of bromine in the presence of acetic anhydride.
The ZnSO4.3Zn(OH)2-H2O system. I. Phase formation
Authors: Bear IJ , Grey IE , Newnham IE , Rogers LJ
Published: September 2010

The bzs-watersystem, where bzs is an abbreviation for ZnSO4.3Zn(OH)2, has been investigated by chemical, X-ray and thermal analyses. The bzs.5H2O was precipitated from solution. Four discrete lower hydrates, namely, the tetra-, tri-, mono- and hemi-hydrates, and an anhydrate were derived from the pentahydrate . The tetra- and tri-hydrates could be prepared by dehydration of the pentahydrate, either thermally or over desiccants; the monohydrate could only be prepared by dehydration of the higher hydrates over desiccants; the hemihydrate and anhydrate could only be prepared by thermal dehydration. Thermal dehydration of the pentahydrate to compositions between the tri- and hemihydrates resulted in the formation of intergrowth structures. Evidence is provided that the layer structure of the pentahydrate persists throughout the series until dehydroxylation of the anhydrate commences. X-ray powder data for the discrete phases have been indexed.
Anomalous E.S.R. Spectra of Nickel Phthalocyanine: A Single-Crystal Study
Authors: Boas JF
Published: September 2010

The e.s.r . spectra of single crystals of nickel(II) phthalocyanine show that there are two different magnetic centres, each with axial symmetry (centre 1, gll 2.0083, gl 2.0018; centre 2, gII 1.986, g1 2.006). In both cases, gllis along the molecular symmetry axis and gl is in the molecular plane. It is proposed that centre 1 arises from a π-radical cation of the type [NiIIPc]x+O2x- analogous to that observed in NiPcI (Schramm et al-1). Centre 2 may arise from a NiIII species.
Spin Crossover in Iron(II) Complexes of 1-Methyl-2-(Pyridin-2-Yl)imidazole and 1-Methyl-2-(Pyridin-2-Yl)benzimidazole
Authors: Sugiyarto KH , Goodwin HA
Published: September 2010

Tris (ligand)iron(II) complexes of 1-methyl-2-(pyridin-2-y1) imidazole and 1-methyl-2-(pyridin-2- y1) benzimidazole are diamagnetic and intensely coloured in solution. Magnetic and electronic and Mossbauer spectral data for the complexes in the solid state show an anomalous temperature-dependence, slight for the imidazole system but strong for the benzimidazole system, which indicates population at elevated temperatures of quintet electronic states. The spin crossover in these systems is displayed to higher temperatures compared to that in the complexes of the unsubstituted ligands. Data from the electronic spectra of the nickel(II) complexes provide a basis for comparison of the behaviour of both the substituted and unsubstituted ligands. These spectra reveal a strong contribution from the 3A2g → lAg spin-forbidden transition which is expected for ligands which exert a field strength close to the iron(II) crossover value.
Photoelectron Spectroscopic Studies of Some Substituted Borotrans
Authors: Peel JB , Rothwell RG , Wang DX
Published: September 2010

The HeI photoelectron spectra of a series of borotrans have been measured. Ab initio molecular orbital calculations using minimum basis sets were performed on the six molecules in this study, by using geometries based on the known structure of the parent borotran, a tricyclic system containing a relatively short B←N dative bond. Temperatures up to 312� were required for the gas-phase measurements and considerable thermal decomposition was observed in two cases. The lowest-energy photoelectron bands are assigned to combinations of oxygen orbitals of the BO3 unit, but the B←N bonding electrons cannot be accurately located in the spectra.
Studies in the Cycloproparene Series: The Generation and Trapping of 1H-Cyclopropa[l]phenanthrene
Authors: Dent BR , Halton B
Published: September 2010

1H- Cyclopropa [l] phenanthrene (4a) has been generated and trapped with furan as cycloadducts (16) and (17). The route to (4a) involves highly regioselective formation of la- methylselenodihydrocyclopropa [I] phenanthrene (60) (80%) by addition of methaneselenolate to 1aH-cyclopropa [I] phenanthrene (7a). Methylation of (60) to give the tetrafluoroborate salt (6p)and subsequent base treatment affords (4a) via the methylselenonium methylide (6q). The non-aromatic laH-cyclopropaphenanthrene (7a) is easily obtained by removal of the elements of chlorotrimethylsilane from chlorides (6m,n). These latter compounds result from half-reduction of the dichlorocarbene adduct (61) of 9-trimethylsilylphenanthrene (51).
Isolation of a Novel Lichen Xanthone From the Genus Diploschistes s. lat
Authors: Elix JA , Gaul KL , Lumbsch HT
Published: September 2010

1,8-Dihydroxy-3,6-dimethoxy-9H-xanthen-9-one ( 1 ) has been isolated from a lichen for the first time and its structure verified by unambiguous synthesis.
Imbricatonol, a Naphthol Naphthoquinone Dimer Isolated From Stypandra imbricata and Dianella revoluta
Authors: Byrne LT , Colegate SM , Dorling PR , Huxtable CR
Published: September 2010

A novel naphthol-naphthoquinone dimer (5), presumably biosynthetically derived from the oxidative coupling of dianellidin (2) with stypandrone (4) or by the incomplete oxidation of stypandrol (I), has been isolated from the plants Stypandra imbricata and Dianella remluta. The structure was elucidated by spectroscopic techniques and confirmed by its chemical modification to form dianellinone (3).
A New Dihydrothiazine Ring Closure for the Preparation of 3-Methylcephalosporins From Azetidinone Disulfides at 5-10-Degrees
Authors: Davis M , Wu WY
Published: September 2010

p - Nitrobenzyl (2R,3R)-2-(benzothiazol-2'-yldithio)-α-isopropenyl-4-oxo-3-phenoxyacetylaminoazetidine-1-acetate (3a), readily prepared from penicillin V, is smoothly cyclized by ammonium acetate in a dimethyl sulfoxideltetrahydrofuran mixture at 5-10� to the ceph-3-em ester (2a) in high yield. Other esters (3b-d), but not the free acid (3e), behave in a similar way. The ceph-3-em esters can be readily de-esterified to the free acid (2e).
Lewis-Base Adducts of Group-11 Metal(I) Compounds. XXIX. Crystal Structures of Bis(Pyridine-4-carbonitrile)silver(I) Nitrate and Bis(4-benzoylpyridine)Silver(I) Nitrate Monohydrate
Authors: Gotsis S , White AH
Published: September 2010

The crystal structures of the title compounds, [Ag(C6H4N2),] (NO3),
(I), and [Ag(C12H9NO)2] (NO3).H2O, (2), have been determined by single-crystal X-ray diffraction methods at ~295 K, being refined by full-matrix least-squares methods to residuals of 0.042 and 0.044 for 1814 and 3434 independent 'observed' reflections respectively. Crystals of (1) and (2) are triclinic P1; for (1) a, 27.954(7), b 6.354(2), c 3.710(1)�, α 87.55(3), β 86.21(2), γ 89.35(2)�, Z 2; for (2), a 17.036(5), b 8.691(3), c 7.849(3) �, α � 107.74(2), β 97 53(2), γ 91 .11(2)�, Z 2. In both structures the formulation is basically a linearly coordinated complex cation/anion as shown above: in (I), Ag-N are 2.214(4), 2.203(4) � with N-Ag-N, 162.2(2)"; in (2), Ag-N are 2.146(3), 2.147(3) �, N-Ag-N, 175.3(1)�. The shortest Ag-O contact is found in (1) at 2.693(4)�. No close contacts are found between the silver atoms and cyano or ketonic ligand substituents.
Potential Inhibitors of Phosphoenolpyruvate (PEP) Carboxylase: Phosphonic Acid Substrate-Analogs Derived From Stobbe-Type Condensations of Ethyl 3-(Diethoxyphosphinoyl)propanoate
Authors: Mcfadden HG , Harris RLN , Jenkins CLD
Published: September 2010

Phosphonic acid analogues of 2-(dihydroxyphosphinoy1oxy)propenoic acid (PEP), the substrate of PEP carboxylase, were prepared and tested as inhibitors of the enzyme. The required triacids were obtained by mild hydrolysis of the partial esters prepared by Stobbe-like condensation of aryl and alkyl carbonyl compounds with ethyl 3-(diethoxyphosphinoyl)propanoate. Condensations with aldehydes gave predominantly (9-propenoates while reactions with ketones gave mixtures of (E)- and (Z)-isomers and also, in some cases, products with the double bond rearranged to the &position. Although compounds tested were inhibitory, none was as effective as previously reported phosphate PEP analogues. Results indicate that the presence of a methyl group cis to the carboxylic acid group enhances inhibitory activity but that trans alkyl groups decrease inhibitor effectiveness.
Selective Aminolysis of Benzoates and Acetates of α-Hydroxy Acids and Phenols With Benzylamine and Butan-1-amine
Authors: Bell KH
Published: September 2010

Benzoates and acetates of a-hydroxy acids and phenols undergo facile aminolysis on treating with benzylamine or butan-1-amine in benzene at room temperature. Under the same conditions acetates and benzoates of alcohols are unaffected.
The Wittig Reaction of 2-t-Butoxycarbonyl-1-methoxycarbonylethylidenetriphenylphosphorane: A Surrogate for the Stobbe Reaction
Authors: Rizzacasa MA , Sargent MV
Published: September 2010

The reaction of 2-t-butoxycarbonyl-l-methoxycarbonylethylidenetriphenylphosphorane (3) with a range of aromatic aldehydes has been explored. The resultant itaconic esters, obtained in high yield, are readily converted into methyl 4-acetoxynaphthalene-2-carboxylates.
Mechanisms of Nucleophilic Attack at Carbon Nitrogen Double-Bonds: The Reaction of Benzohydrazonoyl Halides With Amines
Authors: Hegarty AF , Rigopoulos P , Rowe JE
Published: September 2010

Rate data for the reaction of a series of benzohydrazonoyl halides with pyrrolidine and butan- 1-amine at 303 K are presented. Linear Hammett plots were obtained with each amine. The mechanism of the reactions and the stereochemical outcome of these displacements at the carbon-nitrogen double bond are discussed.
The Chemistry of Eremophila Spp. XXIX. The Absolute Configuration of (+)-Syringaresinol Dimethyl Ether
Authors: Bytheway IR , Ghisalberti EL , Gotsis S , Jefferies PR , Skelton BW , Sugars KE , White AH
Published: September 2010

The absolute configuration of the title compound has been established from a single-crystal room temperature X-ray structure determination of its dibromo derivative, C24H28Br2O8. Crystals of the latter are orthorhombic, space group P21212, a l6.696(5), b l5.660(3), c 4.713(1) �, Z 2; 1452 independent 'observed' reflections yielded R 0.033 following full-matrix least-squares refinement. The molecule lies on a crystallographic 2 axis. The occurrence of lignans in Eremophila species is summarized.
The Chemistry of Laurenene. VIII. Laurena-1(15),2-diene, Laurena-1,14-diene and Lauren-1(15)-ene
Authors: Perry NB , Weavers RT
Published: September 2010

The naturally occurring diterpene lauren-1-ene (1a) has been converted into its thermodynamically less stable isomer, lauren-1(15)- ene (3), via laurena-1(15),2-diene (5). Laurena-1,14-diene (7) was also synthesized. Conformational mobility in some of these laurenane systems has been revealed in their 13C n.m.r. spectra.
Oxygen Exchange and Cleavage of the Glycinate Chelate [Co(H2NCH2CH2NH2)2(H2NCH2CO2)]2+ in Strongly Alkaline Solution
Authors: Buckingham DA , Clark CR
Published: September 2010

Cleavage of the carboxylate chelate [Co(en)2(glyO)]2+ has been studied in 0.75 mol dm-3 NaOH . 18O-tracer results are interpreted as 16% C-O and 84% Co-O bond fission, the products ultimately being [Co(en)2(OH)2]+, CoII, and glyO -. The major Co-O cleavage path is interpreted as an SN1 (CB) process leading to both recapture of carboxylate oxygen (50%, kex = 4.8 × 10-6 s-1) and capture of solvent leading to [Co(en)2(OH)( glyO )]+ (50%).
The Stereochemistry of Organometallic Compounds. XXX. Hydrocyanation of Alkynol Ethers: a New Stereospecific Route to α-Alkylidene γ-Lactones
Authors: Jackson WR , Perlmutter P , Smallridge AJ
Published: September 2010

The regioselectivity of hydrocyanation of a range of protected α- and β-hydroxyalkynes has been investigated and shown to be highly susceptible to steric effects. Some of the products from hydrocyanation of protected β-hydroxyalkynes have been converted into α-alkylidene γ- lactones.
Micellar Catalysis of Organic-Reactions. XXI. A Comparison of the Catalytic Activity of Micelles of Cetyltrimethylammonium Bromide and Sulfate on Ester, Amide and Carbamate Hydrolyses
Authors: Broxton TJ , Christie JR , Mannas SM
Published: September 2010

The basic hydrolyses of phenyl acetate, N,4-dimethyl-N-(3′- nitrophenyl ) benzamide , methyl N-methyl-N-(4′-nitrophenyl) carbamate and methyl N-(3′,5′-dinitrophenyl)-N-methylcarbamate have been studied in cationic micelles of cetyltrimethylammonium bromide (ctab) and sulfate (ctas). Hydrolysis of phenyl acetate and the 4′-nitro carbamate, which involve rate-determining hydroxide attack, exhibit weak catalysis by both micelles, and the observed rates in each micelle are similar. The hydrolysis of the benzamide and the 3′,5′-dinitro carbamate, which involve rate determining C-N bond breaking, show larger catalysis, and, furthermore, micelles of ctab are more effective than micelles of ctas. The observed rates can be explained by the pseudo-phase kinetic model. For reactions involving rate-determining hydroxide attack, the calculated second-order rate constants in micelles of ctab and ctas are similar and much less than those for reaction in water. For reactions involving rate-determining C-N bond breaking the calculated second-order rate constants in micelles of ctab are greater than in micelles of ctas, and similar to those for reaction in water.
The Thermal α-Substitution of Dimedone by Vinyl Ethers
Authors: Pinhey JT , Xuan PT
Published: September 2010

Pyrolysis of a mixture of dimedone (1) and 1-methoxycyclohexene (2) led to formation of the enedione (3), which underwent both a Diels-Alder reaction with (2) to form the spiro compound (4), and reaction with oxygen to give the cyclic peroxide (5). The possibility of extending the initial reaction, which is thought to proceed by an ene mechanism, to some cyclic vinyl ethers has been examined.
The Crystal Structure of S-Methyl 1-[Dicyclohexyl(thiophosphoryl)]-dithioformate: (c-C6H11)2P(S)C(S)Sme
Authors: Hoskins BF , Tiekink ERT
Published: September 2010

The crystal structure of the title compound, (c-C6H11)2P(S)C(S)SMe , has been determined and shows that the P(S)C(S)SC chromophore is situated on a crystallographic mirror plane with the cyclohexyl groups related to each other across this plane. Significant interatomic distances are: P=S 1.951(1), P-C 1.860(4), C=S 1.632(4) and C-S 1.700(4)Ǻ. A resonance scheme involving the delocalization of π-electrons over the CS2 moiety has been invoked to account for the observed C-S bond distances in the molecule. Crystals are orthorhombic, space group Pnma with unit cell parameters a 10.196(2), b 10.612(1) and c 15.370(3)Ǻ, and Z 4. The structure was solved by direct methods and refined by a full-matrix least-squares procedure to final R 0.045, Rw 0.047 for 1191 reflections with I ≥ 3.0σ(I).
Derivatives of the Benzo[5,6]cyclohepta[1,2,3-Cd]thieno[3,2-C]pyridine System. X-Ray Crystal Structure of 8,9-Dimethoxy-1,2,3,6,11,11a-hexahydrobenzo[5,6]cyclohepta[1,2,3-Cd]thieno[3,2-C]pyridine-1-carbonitrile
Authors: Bremner JB , Browne EJ , Engelhardt LM , Hyland BA , James GS , White AH
Published: September 2010

During attempts to prepare 9,10-dimethoxy-4,7,12,12a-tetrahydro-5H- benzo [g] thieno [3,2-a] quinolizine (1), and subsequent cyanogen bromide- induced ring cleavage of this tetracyclic base, two by-products were isolated. The preparations of these two compounds are described, and their structures elucidated as 8,9-dimethoxy-1,2,3,6,11,11a-hexahydrobenzo [5,6] cyclohepta [1,2,3-cd] thieno [3,2-c]pyridine (5a), and its 1-carbonitrile derivative (5b). An N-methyl derivative (5c) has been prepared from (5a). These products (5) are the first examples of a new heterocyclic system. The crystal and molecular structure of the cyanamide (5b) has been determined by X-ray crystallographic methods.
N-Alkylations and O-Alkylations of Nitro-Substituted 1,3-Diphenylureas: Preparations of Propellant Stabilizer Derivatives
Authors: Curtis NJ
Published: September 2010

A procedure has been
developed for the N- ethylation and methylation of 1,3-diphenylureas, ArNRCONHAr′ (R = H, Me or Et), through treatment with sodium hydride and iodoalkane in dimethylformamide. The reaction was general, provided that the aniline to be alkylated was substituted with no more than one nitro group. ArRNCONR′Ar′ derivatives prepared were: R = R′ = Et (and Me); Ar =
phenyl, Ar′ = 2-nitrophenyl and 4- nitrophenyl ; Ar = 2-nitrophenyl, Ar′ = 2-nitrophenyl and 4-nitrophenyl; Ar = Ar′ = 4-nitrophenyl. Two mixed derivatives were also prepared: R = Et, R′ = Me, Ar = phenyl, Ar′ = 2-nitrophenyl and 4-nitrophenyl. O-Alkylated isourea products were obtained in the reactions of 1-(2,4- dinitrophenyl )-3-(2-nitrophenyl)urea and 1-(2,4-dinitrophenyl)-3-(4- nitrophenyl )urea. The use of potassium carbonate as the base led to apparently exclusive O- alkylation of 1,3-bis(2-nitrophenyl)urea although the reaction was not general. 1-(2,4-Dinitrophenyl)-1,3- diethyl-3-phenylurea was prepared by using silver oxide and obtained as a mixture with the isourea . Many of the compounds prepared are important nitro derivatives of the propellant stabilizers, ethyl and methyl centralite.
Synthesis of Phosphonodidepsipeptides through Esterification of [1-(Benzyloxycarbonylamino)alkyl]phosphonic Acids
Authors: Hoffmann M
Published: September 2010

The synthesis is reported of phosphonodidepsipeptides (3) through esterification of [1-( benzyloxycarbonylamino )alkyl] phosphonic acids (1) with α- hydroxy acid p-nitrobenzyl esters (2) in the presence of thionyl chloride in dimethylformamide.
Synthesis of Deuterated Derivatives of 2,2',4,4',6,6'-Hexanitrobibenzyl and 2,2',4,4',6,6'-Hexanitrostilbene
Authors: Dagley IJ
Published: September 2010

The α- deuterated and perdeuterated derivatives of the high explosives 2,2′,4,4′,6,6′-hexanitrobibenzyl (HNBB) and 2,2′,4,4′,6,6′- hexanitrostilbene (HNS) have been prepared from the corresponding derivatives of 2,4,6-trinitrotoluene (TNT). Nuclear hydrogen exchange reactions, catalysed by hydroxide ion, have been shown to compete with α-hydrogen exchange reactions for TNT in dimethylformamide-D2O and during the conversion of TNT into the derived α-chloride and HNBB by using alkaline hypochlorite. These nuclear exchange reactions have been suppressed by lower reaction temperatures or substitution of tertiary amine bases for hydroxide ion. HNBB does not undergo substantial base- catalysed deuterium exchange reactions and is converted into HNS under these conditions.
Oxidative Coupling of Lignans. IV. Monophenolic Oxidative Coupling
Authors: Burden JK , Cambie RC , Craw PA , Rutledge PS , Woodgate PD
Published: September 2010

Oxidative coupling of the monophenolic monoester (6) gives an aryltetralin (12) which is a potential intermediate for the synthesis of clinically active monophenolic lignan lactones. In contrast, oxidative couplings of the monophenols (32) and (35), derived from matairesinol (29), give mixtures of diastereoisomeric cyclooctadiene lignans while 4′-demethyldeoxypodorhizon (26) does not cyclize . These results show that the degree of aromatic substitution in monophenolic diarylbutanes plays an important role in determining the outcome of oxidative coupling. An alternative synthesis of the lactone (57) from piperonal has been investigated.
The Chemistry of Pyrimidinethiols. II. The Preparation and Reactions of Some 2-Arenecarbonylmethylthiopyrimidines
Authors: Hurst DT , Beaumont C , Jones DTE , Kingsley DA , Patridge JD , Rutherford TJ
Published: September 2010

A number of 2-arenecarbonylmethylthiopyrimidin-4(1H)-ones has been synthesized. Those having H, Me or Pr as a 6-substituent undergo ready sulfur extrusion on heating in diphenyl ether to give 2- ( arenecarbonylmethylene )-2,3-dihydropyrimidin-4(1H)-ones, but those that have a 6-amino substituent or a 5-methyl substituent did not undergo this reaction under these conditions. Some other arenecarbonylmethylthiopyrimidines also did not undergo sulfur extrusion under these conditions. The methylenepyrimidinones formed from 6-methyl-(and 6-propyl-) pyrimidines show two 1H n.m.r. signals for both the pyrimidine H 5 and for the methylene H which collapse to single signals on raising the temperature to about 100°C. The methyl signal similarly appears as a double signal which collapses to one on heating. We interpret this as being due to the existence of two thermally isomerized cis and trans forms of the methylenepyrimidinones. However, for the 4-phenylbenzoyl and the 2-naphthoyl compounds this multiplicity of signals was not seen. The same effect was observed for the 3-methoxyphenyl and 2,5- dimethoxyphenyl derivatives. Cyclization of the arenecarbonylmethylthiopyrimidinones in sulfuric acid at ambient temperature yields 5H-thiazolo[3,2-a]pyrimidin-5-ones.
The Synthesis of Some Pyrimidinyl and Thiazolyl Ureas and Thioureas and Some Related Compounds
Authors: Hurst DT , Stacey AD , Nethercleft M , Rahim A , Harnden MR
Published: September 2010

Some pyrimidin-2- and pyrimidin-4-amines were treated with isocyanates and isothiocyanates to give the corresponding disubstituted ureas or thioureas . A pyrimidin-2-amine is more reactive than a pyrimidin-4- amine in these reactions. 2-Aminothiazoles and thiazolinones also react to give the disubstituted ureas or thioureas . The use of ethoxycarbonyl or benzoyl isothiocyanate or isocyanate gives products which are readily hydrolysed to the pyrimidinyl or thiazolyureas or thioureas but with concomitant hydrolysis and decarboxylation of an ethoxycarbonyl substituent . The use of chlorosulfonyl or trimethylsilyl isocyanate gives the urea derivative without isolation of the intermediate disubstituted urea. Some related compounds were also synthesized.
Substituted Ruthenium Triammine Complexes: The Crystal Structure of Triammineaqua(pentane-2,4-dionato)ruthenium(III) Dithionate Dihydrate, [Ru(NH3)3:(acac)(OH2)][S2O6].2H2O
Authors: Diamantis AA , Moritz PS , Snow MR , Tiekink ERT
Published: September 2010

The complex [ Ru (NH3)3( acac )(OH2)]2+ was obtained by the reaction of [ Ru (NH3)3(H2O)3][CF3SO3]3 with pentane-2,4-dione. The crystals are orthorhombic, space group P212121, with a 7.805(4), b 12.997(4), c 17.479(13) Ǻ, U 1773.1 Ǻ3 with Z 4. The structure was refined by a full-matrix least-squares method on 827 reflections [for which I ≥ 2.5σ(I)] to final R 0.042 and Rw 0.043. The structure analysis reveals an almost perfect octahedral coordination around the ruthenium atom with the three ammine ligands attached in a facial arrangement. Spectroscopic and electrochemical studies are consistent with the same species being present in dilute solution.
Carbonyl Halides of the Group-6 Transition Metals. XXIX. The Crystal and Molecular Structure of [Mo(CO)2dpmSe)2Cl]2[Mo6O19].4CH3NO2[dpmSe = (Ph2PCH2P(Se)Ph2]
Authors: Colton R , Hoskins BF , Panagiotidou P
Published: September 2010

Crystals of [Mo(CO)2( dpmSe )2Cl]2 [Mo6O19].4CH3NO2 are triclinic, Pī , a 12.985(3), b 13.981(3), c 17.200(3)Ǻ, α 91.55(2), β 92.00(2), γ 101.12(2)°. In the cation, [Mo(CO)2(dpmSe )2Cl]+, the molybdenum atom is seven-coordinate with a slightly distorted capped octahedral environment. A carbonyl group occupies the capping position, and both dpmSe ligands display bidentate coordination. The dimensions of the anion are very similar to those previously reported.
Dynamics of the Bis-Tris and High Spin-Low Spin Equilibria of 2-(2′-Pyridyl)imidazoleiron(II) Complexes in Dimethyl Sulfoxide Solutions
Authors: Beattie JK , Mcmahon KJ
Published: September 2010

Ultrasonic and temperature-jump relaxation kinetics have been used to observe, respectively, the spin equilibrium and tris-bis ligand dissociation equilibrium of the 2-(2′-pyridyl) imidazoleiron (II) complexes in dimethyl sulfoxide solutions. In the ultrasonic experiments a single relaxation curve describes the excess sound absorption with a relaxation time of 73�3 ns. This was identified as perturbation of the singlet-quintet spin equilibrium by comparison with previous laser temperature-jump measurements in other solvents and by the temperature dependence of the relaxation amplitude. The equilibrium constant for the singlet-quintet transition was determined by the Evans n.m.r . method to be 0.48 at 298 K. From the relaxation time and the equilibrium constant the rate constants for the spin-equilibrium transition can be calculated to be k15 of 4.5×106 s-1 and k51 of 9.4×106s-1. In the temperature-jump experiments a millisecond relaxation time was observed. The dependence of the relaxation time on the concentration of the free ligand is of the form kobs = a + b[L]. From the ratio b/a an equilibrium constant for the perturbed process can be calculated. An independent measure of this equilibrium constant was obtained from spectrophotometric measurements. The rate constants for the formation and dissociation of the tris complex are calculated to be 2.8 × 104 dm3 mol-1 s-1 and 2.1 × 102 s-1, respectively, at 298 K.
Comparative Calorimetric and 1H N.M.R. Studies of the Interaction of Ag(I) With a Series of Mixed-Donor Macrocycles Incorporating Nitrogen, Oxygen and or Sulfur Donor Atoms
Authors: Baldwin D , Lindoy LF , Graddon DP
Published: September 2010

The interaction of silver ion with a range of mixed-donor macrocyclic ligands incorporating nitrogen, oxygen and/or sulfur donors has been investigated. Complementary calorimetric and n.m.r. studies in acetonitrile (and its deuterated derivative) were used to investigate the nature of the equilibria present as the metal/ ligand ratio was varied. In all systems the formation of a 1 : 1 species was observed, with a 1:2 (metal/ ligand ) species also being formed in the presence of excess ligand in the majority of cases. Enthalpies of formation for the various complexes have been determined. Stepwise stability constants for the respective [ AgL ]+ + L ↔ [AgL2]+ equilibria have been estimated from the calorimetric titration data, and the factors promoting the formation of the 1:2 species are discussed. The studies confirm the enhanced affinity of AgI for thioether donors over ether donors.
Cyclometallation Reactions. XXI. Some Chemistry of Binuclear Manganese Complexes Derived From Azobenzene: X-Ray Crystal-Structures of {Mn (CO)4}2(μ- C6H4N=NC6H4) and {Mn (CO)4}{ Mn (CO)3[P(OPh)3]}(μ-C6H4N=NC6H4)
Authors: Bruce MI , Liddell MJ , Snow MR , Tiekink ERT
Published: September 2010

The reaction between azobenzene and Mn (CH2Ph)(CO)5, carried out in refluxing n-octane, afforded the binuclear complex {Mn (CO)4}2(μ- C6H4N=NC6H4) (2) as the first isolable product; subsequent reaction with azobenzene gave Mn (C6H4N= NPh )(CO)4. With P( OPh )3, the binuclear complex undergoes CO substitution but not hydrogen transfer, to give {Mn (CO)4}{ Mn (CO)3[P(OPh)3]}(μ-C6H4N=NC6H4)(3). The X-ray crystal structures of the title complexes have been determined. Compound (2) crystallizes in the monoclinic space group P21/c with unit cell
dimensions a 10.161(2), b 23.586(4), c 13.091(4)Ǻ, β 97.10(2)° with Z = 6; crystals of (3) are triclinic, space group Pī , a 12.886(3), b 13.920(3), c 10.428(7)Ǻ, α 97.11(4),β 102.60(4), γ 81.78(2)°. The structures were refined by a full-matrix least-squares procedure to final R 0.041 and Rw 0.048 for 3459 reflections with I ≥ 2.5σ(I) for (2), and R 0.095 and Rw 0.106 for 3406 reflections for (3).
Potential Antimalarials. VII. Di-Mannich Bases of 4-[(7'-Trifluoromethylquinolin-4'-yl)-Aminophenol and 4-(7'-Bromo-1',5'-naphthyridin-4'-yl)]-aminophenol via 4-Nitrophenols
Authors: Barlin GB , Ireland SJ
Published: September 2010

A series of di-Mannich bases have been prepared from 4-nitrophenol and paraformaldehyde with dimethylamine, diethylamine, dipropylamine, N- (2′-hydroxyethyl)methylamine, piperidine , 3- and 4-methylpiperidine, 3,5-dimethylpiperidine or pyrrolidine. These nitro compounds were reduced catalytically to the corresponding 4-aminophenols, which reacted with 4-chloro- 7-trifluoromethylquinoline and 7-bromo-4-chloro- 1,5-naphthyridine to give the required di-Mannich bases of 4-(7′- trifluoromethylquinolin-4′-yl)- and 4-(7′-bromo-1′,5′-naphthyridin-4′-yl)-aminophenol.
Axially Asymmetric Metal Alkyls. VII. Crystallographic Characterization of λ-(R,R) and δ-(S,S)-[ZrL(η-C5H5)2], L = [2-CH(SiMe3)C6H4]22-
Authors: Raston CL , Skelton BW , Twiss P , White AH
Published: September 2010

The single-crystal X-ray structural
characterization of λ-(R,R)-and δ- (S,S)-[ ZrL (η-C5H5)2], L = [2-CH(SiMe3)C6H4]22-, is recorded for comparison with the λ-(R,S)-/δ-(S,R)-isomer, previously reported.
Cementation of Lead From Lead Sulfate Slurries. I. Kinetics With Zinc Precipitant
Authors: Bear IJ , Flann RCA , Woods R , Gardner JR
Published: September 2010

The cementation of metallic lead from two samples of lead sulfate powders with zinc precipitant has been studied in stirred aqueous slurries. The reaction proceeded by dissolution of the lead sulfate and precipitation of the lead from solution. The kinetics were characterized by two alternative reaction profiles; in profile No. 1, the extent of reaction rose steeply during the first 15-60 min to a gently sloping incline or plateau, while in profile No. 2 the initial rise was less sharp but the reaction continued to completion at a steady rate. Profile No. 1 was observed under all conditions studied with the lead sulfate sample that had the faster dissolution rate. The other sample gave rise to profile No. 2 when the initial partial pulp density (IPPD) of lead sulfate was 100 g/l. or higher, and to mixed No. 1 and No. 2 kinetics at lower values. The rate of reaction increased with decrease in the IPPD of lead sulfate when the kinetics followed profile No. 1, whereas the reverse condition was evident when profile No. 2 was operative.
Synthesis and Properties of Achiral Coronands Incorporating the Sulfide and Sulfoxide Functionality
Authors: Raguse B , Ridley DD
Published: September 2010

A number of polyether coronands incorporating sulfide and sulfoxide functionality and five or six ether oxygen atoms were prepared, their formation of complexes with alkali metal and ammonium salts were studied and the results were compared with analogous phosphorus- containing coronands reported previously. It is evident that ring size played a more important role than the ability of a group to complex in systems with five ether oxygen atoms in which the sulfide-containing coronands actually formed stronger complexes than the corresponding sulfoxide coronands . When the number of ether oxygen atoms in the ring was six, however, it appeared that complexation occurred with the ether oxygen atoms and little contribution came from the sulfur centres.
Baeyer-Villiger Oxidation of 10-Methyl-9-Anthraldehyde: Formation and Photochemical Dimerization of 9-Formyloxy-10-methylanthracene
Authors: Becker HD , Skelton BW , Turner AB , White AH
Published: September 2010

Oxidation of 10-methyl-9-anthraldehyde with hydrogen peroxide in acetic acid in the presence of sulfuric acid gives 9-formyloxy-10-methylanthracene which dimerizes in solution upon exposure to light. The head-to-tail structure of the 4π+4π photodimer was established by a single-crystal X-ray diffraction study. In the crystalline state, the molecular structure is centrosymmetric, and the length of the photochemically formed bonds 1.646(4)Ǻ. Crystals are monoclinic, P21/c, a 7.980(5), b 16.143(7), c 9.571(3)Ǻ, β 114.38(3)°, Z=2 dimers; R was 0.041 for 1362 'observed' diffractometer reflections.
Lewis-Base Adducts of Group 11 Metal(I) Compounds. XLIII. Synthesis and Structural Systematics of 1 : 1 Copper(I) Halide/Nitrogen Base Adducts as [(N-base)1(CuX)1]∞ 'Split-Stair' Polymers (X = Cl, Br, I; N-Base = Acridine, Quinaldine and 2,6-Dimethyl- and 2,4,6-Trimethyl-Pyridine)
Authors: Healy PC , Kildea JD , Skelton BW , White AH
Published: September 2010

The complete array of single strand ('split-stair') polymers for the 1 : 1 system CuX/monodentate nitrogen base, L, all X= Cl, Br, I, has now been synthesized and structurally characterized by
using the highly hindered pyridine bases, L= acridine and quinaldine . Similar polymers, [ LCuX ] ∞, are also obtained with L = 2,6-dimethylpyridine for X = Cl, Br (but not I which is a dimer , [LCuI2CuL]), and for L = 2,4,6- trimethylpyridine, X = Br, I (but not Cl, which is ionic [CuL2]+[CuCl2]-). A general feature of all polymeric structures, although diverse in space group and not isomorphous in respect of polymer disposition, is the presence of a short crystallographic axis (about 4 � ) as the unit translational repeat distance.
Lewis-Base Adducts of Group 11 Metal(I) Compounds. XLVI. Synthesis and Conformational Systematics of Some Novel Polymeric Adducts of Pyridine-4-carbonitrile With Copper(I) Halides
Authors: Graham AJ , Healy PC , Kildea JD , White AH
Published: September 2010

The isolation and structural characterization of 1 : 1 adducts of copper(1) chloride (1) and bromide (2) with pyridine-4-carbonitrile (L) is described; crystals of the two complexes are isomorphous (monoclinic, P21/c, a ≈ 3.9, b ≈ 14.7, c ≈ 13.0 � , β ≈ 96°, Z 4; R0.047, 0.063 for No 630, 707 'observed' reflections respectively). Unlike the 1 : 1 adducts with the parent pyridine and benzonitrile ligands which are 'stair' polymers, these complexes comprise 'split-stair' strands woven into a two-dimensional sheet by crosslinking ambidentate ligands. Cu-N ( nitrile ) (1.942(9), 1.96(1) � ) are appreciably shorter than Cu-N (pyridine) (2.066(8), 2.04(1) � ), as in the parent base complexes. The two Cu-X are similar in each case: 2.336(6), 2.366(3) � (CI); 2.460(3), 2.486(3) � (Br). The iodide adduct (3) isolated is of novel stoichiometry (Cul : L, 4 : 5) (monoclinic, P21/c; a 10.140(5), b 12.214(6), c 15.157(8) � , β 99.99(4)° Z 2; R 0.048, No 2416). It is a linear polymer, comprising tetranuclear Cu414L4 'step' units, crosslinked across inversion centres by disordered ambidentate ligands.
Lewis-Base Adducts of Lead(II) Compounds. III. Synthesis and Structural Characterization of Mononuclear (Nitrato-O,O′)bis(1,10-phenanthroline)-(thiocyanato-N)lead(II)
Authors: Engelhardt LM , Patrick JM , White AH
Published: September 2010

The isolation and single-crystal X-ray structure determination of the title compound, [(phen)2Pb(NCS)(O2NO)] is described; crystals are triclinic, P1, a 15.554(7), b 9-670(4), c 8.429(3) α 72.53(3), β 81.90(3), γ 72.88(3)� Z = 2, yielding R 0.052 for 3405 independent 'observed' reflections. The lead atom is seven-coordinate [Pb-N 2.49(1)-2.60(1) (phen), 2.89(1) (NCS); Pb-O 2.75(1), 2.89(1) �] with a large vacancy in the coordination sphere, possibly indicative of a stereochemically active lone pair.
Intramolecular Quadridentate Synthesis: X-Ray Crystallographic Analysis of [(NH2CH2CH2NH2)Co(NH2(CH2)2N = C(NH2)CH2S(CH2)2NH2)](CF3SO3)3.H2O
Authors: Roecker L , Lydon JD , Willis AC , Sargeson AM , Deutsch E
Published: September 2010

Meridional forms of N3S quadridentate complexes of the type [(en)Co(NH2(CH2)2 N=C(R′)CH2S(CH2)2NH2)]3+ with R′ = CH3 and NH2) are readily prepared from [(en)2Co(S(R)CH2CH2 NH2)]3+ (with R = CH2COCH3 and CH2CN, respectively; en = ethane-1,2-diamine) in basic solution. The X-ray crystallographic analysis of the complex with R1= NH2 was determined as the monohydrate of its triflate salt and shown to have a β-type configuration of the quadridentate. Crystals are monoclinic, space group C2/c with a 23.337(1), b 11.973(1), c 20.015(1) � , β 95.12(1)�, and Z 8. 3183 data with 1 ≥ 3 σ (1) were refined to conventional R factors of 0.056 and 0.072.
Chemistry of the Podocarpaceae. LXXIV. The Conversion of Podocarpic Acid Into γ-Bicyclohomofarnesals
Authors: Cambie RC , Clark GR , Goeth ME , Rickard CEF , Rutledge PS , Ryan GR , Woodgate PD
Published: September 2010

Podocarpic acid (15) has been converted into the ambergris odorant γ-bicyclohomofarnesal (1) and two analogues (2) and (3). The stereochemistry of the intermediate keto ester (24) has been confirmed by a single-crystal X-ray determination.
Novel Bromo Metabolites From a Dictyoceratid Sponge of the Cacospongia Genus
Authors: Garson MJ , Manker DC , Maxwell KE , Skelton BW , White AH
Published: September 2010

Two novel brominated metabolites, tribromocacoxanthene (3) and tetrabromocacoxanthene (4),have been isolated from a marine sponge of the Cacospongia genus (family Thorectidae ) along with 12-epideoxoscalarin (2). The structures of compounds (3), systematic name (2S,4aS,9aS)-2,7-dibromo-4a-bromomethyl-1,1-dimethyl-2,3,4,4a,9,9a-hexahydro-1H-xanthene, and (4), systematic name (2S,4aS,9aS)-2,5,7-tribromo-4a-bromomethyl-l,1-dimethyl-2,3,4,4a,9,9a-hexahydro-1H-xanthene , were deduced from analysis of 1H and 13C n.m.r. data and that of (3) was confirmed by X-ray crystallographic structure analysis which provided the absolute configuration. The two new compounds are the first tricyclic examples of a carbon skeleton previously isolated only from algae. The chemotaxonomic implication of the isolation of these new compounds is discussed.
Potential GABAB Receptor Antagonists. II. Synthesis of 1-[2-Amino-1-(4-chlorophenyl)ethyl]-3-oxo-1,3-dihydroisobenzofuran-1-carboxylic Acid
Authors: Janowski WK , Prager RH
Published: September 2010

Michael addition of methyl 3-oxo-1,3-dihydroisobenzofuran-1-carboxylate to nitrostyrenes is catalysed by amine bases. In non-polar solvents, the use of both enantiomers of ψ-ephedrine as base (0.1 equiv.) leads to both enantiomers , respectively, of a single diastereoisomer. When the reaction mixture is heated, the reaction is neither diastereoselective nor enantioselective. The products have been converted into the potential GABAB analogue 1-[2-amino-1-(4-chlorophenyl )ethyl]-3-oxo-1,3-dihydroisobenzofuran-1-carboxylic acid.