bluuebunny/crossref_metadata_2025 huggingface dataset:
Elimination of Molecular Hydrogen and Methane from Collision-Activated Alkoxide Negative Ions in the gas Phase. An ab initio and Isotope Effect Study
Authors: Hayes RN , Sheldon JC , Bowie JH , Lewis DE
Published: September 2010

Ab initio calculations indicate that the collisional induced losses of molecular hydrogen from the ethoxide negative ion and methane from the t- butoxide negative ion to be stepwise processes in which the key intermediates are [H-… MeCHO ] and [Me-…Me2CO] respectively. Deuterium kinetic isotope effects observed for these and other alkoxide negative ions are in accord with the operation of a stepwise reaction.
Chlorosulfination of Aromatic Methyl Ethers with Thionyl Chloride
Authors: Bell KH
Published: September 2010

Aromatic sulfinyl chlorides have been prepared in high yield by direct chlorosulfination of some aromatic ethers (1,3-dimethoxybenzene, 2- methyl- and 4-chloro-1,3-dimethoxybenzene, 1,2,3-trimethoxybenzene, 1- and 2-methoxynaphthalene, 1,5-, 1,7-, 2,6- and 2,7- dimethoxynaphthalene ) with thionyl chloride alone at or below room temperature. Under the same conditions, 1,4-dimethoxynaphthalene and 1,3-dimethoxy-5-methylbenzene yield chlorinated starting materials and sulfides. 1,3,5-Trimethoxybenzene yields chlorinated starting material, sulfide, and a chlorinated disulfide. Some other ethers (e.g. anisole, 1,2- and 1,4-dimethoxybenzene, 5-chloro-1,3-dimethoxybenzene) are unreactive under these conditions.
Pentakis(methoxycarbonyl)cyclopentadiene Chemistry. IX. Some Derivatives Containing Copper(I): X-Ray Structures of [Cu{C5(CO2Me)5}(Eph3)2] (E=P and As) and [{Cu(AsPh3)3}2(µ-O2CMe)][C5(CO2Me)5]
Authors: Bruce MI , Humphrey PA , Patrick JM , Skelton BW , White AH , Williams ML
Published: September 2010

Reactions between Cu{C5(CO2Me)5}2 and excess PPh3, or between PPh3 and a methanolic solution of Cu2O in HC5(CO2Me)5('Cu{C5(CO2Me)5}'), have given Cu{C5(CO2Me)5}(PPh3)2; the P(C6H4Me-p)3 complex was also obtained, while addition of Ph2P(CH2)2PPh2 (dppe) to 'Cu{C5(CO2Me)5}' gave the salt [Cu(dppe)2] [C5(CO2Me)5]. Cu{C5(CO2Me)5}(AsPh3)2
was obtained similarly from AsPh3 and 'Cu{C5(CO2Me)5}' or from [CuI(CNMe)(AsPh3)]2 and Tl{C5(CO2Me)5}. The X-ray structures of Cu{C5(CO2Me)5}(EPh3)2 (E = P, As) show the complexes to have copper approximately tetrahedrally coordinated by the two EPh3 ligands and two carbonyl oxygens from adjacent CO2Me groups on the C5 ligand. The X-ray structure of [{Cu(AsPh3)3}2(μ-O2CR)] [C5(CO2Me)5] is also reported: an acetate or formate ligand bridges two Cu(AsPh3)3 units in the cation; the anion is a disordered C5(CO2Me)5- anion. Cu{C5(CO2Me)5}(PPh3)2 is monoclinic, space group P21/c, with a 9.151(5), b 19.28(1), c 27.78(2) Ǻ, β 95.21(5)°, Z 4; 2710 independent observed data were refined to R 0.072, R′0.084. Cu{C5(CO2Me)5}(AsPh3)2 is isomorphous, with a 9.105(4), b 19.198(11), c 27.85(2) Ǻ, β 92.86(4)°, Z 4; 4684 independent observed data were refined to R 0.045, R′ 0.035. [{Cu(AsPh3)3}2(μ-O2CMe)] [C5(CO2Me)5] is monoclinic, space group P2/n, with a 23.214(9), b 13.141(4), c 18.326(6)
Ǻ, β 94.95(3)°, Z 2; 1896 independent observed data were refined to R 0.072, R′ 0.081.
Photochemical Isomerization of (E,Z)-1,5-Bis(9-anthryl)penta-1,4-dien-3-one and its Intramolecular Diels-Alder Adduct
Authors: Becker H , Skelton BW , White AH
Published: September 2010

Photoexcitation of (E,Z)-1,5-bis(9-anthryl)penta-1,4-dien-3-one (2)
leads to 4-(9-anthryl)-4,5-dihydro-5,9b[1′,2′]-benzeno-9bH- benz [e]indene-3(3aH)-one (3) which is formed by an intramolecular Diels -Alder addition. Upon irradiation, (3) undergoes a skeletal rearrangement to give a product (4), rationalized in terms of a stepwise reaction involving diradical intermediates. The molecular structure of (4) has been established by X-ray diffraction, and the stereochemistry of (3) deduced from the results of X-ray diffraction studies of its reduction products (5) and (6).
The Atomic Exciton Model for the Excited States of p-Electron Systems
Authors: Schipper PE
Published: September 2010

A new model is presented to describe the π-π* excitations of π-electron systems in terms of intra-atomic excitations. The atomic exciton model combines features of conventional exciton and valence bond theory, reducing to the former in the non-exchanging limit, and the latter in the ground-state limit with covalent structures. The model is ideally suited to the approximate or exact incorporation of exchange, and highlights the opposition of excitation and electron interchange in determining the energetics of the excitation manifold, eliciting thereby the essential difference between ground and excited states. Applications to some simple π-systems are considered, providing new insight into their excited states.
Osmium(III) Halide Complexes with para-and meta-Substituted Benzeneseleninato Ligands
Authors: Graziosi G , Preti C , Tosi G , Zannini P
Published: September 2010

New complexes of osmium(III) with para - and meta-substituted benzeneseleninic acids of the type XC6H4SeO2H (X = H, p- Cl , m- Cl , p-Br, m-Br, p-Me) are reported. The compounds, of the type Os(XC6H4SeO2)3, Os(XC6H4SeO2)2Y, Os(XC6H4SeO2)Y2 and Os2(XC6H4SeO2)3Y3 (Y = Cl , Br), have been studied through spectroscopic techniques ( i.r ., far- i.r .and electronic spectra), magnetic susceptibility measurements, thermogravimetric studies and conductivity measurements. The wavelengths of the principal electronic absorption peaks have been accounted for quantitatively in terms of the crystal-field theory; the nephelauxetic parameter is indicative of an appreciable metal- ligand covalency. It is worth noting that among the present complexes the highest q values are related to the Os(XC6H4SeO2)3 derivatives in which OsO6 chromophores are present; the Dq values decrease on passing to the 1 : 2, 1 : 1.5 and 1 : 1 metal/ ligand molar ratio complexes according to the presence of chlorine- and bromine-containing chromophores . The i.r . data point to a seleninato -O,O′ coordination for all the complexes; in particular, the presence of three SeO bands with the irreducible representation A2 + 2E in the i.r . spectra of the tris derivatives suggests an octahedral configuration with D3 symmetry. All the halo complexes are polymeric octahedral with bridging halide atoms. The magnetic moment values lie in the expected range for the trisbenzeneseleninato derivatives, and they decrease on passing to the halo complexes.
Concerning the Problem of the Isokinetic Relationship. IV. The Evaluation of the Isosubstituent Hammett Parameter by Means of Isokinetic and Isoequilibrium Temperatures
Authors: Linert W
Published: September 2010

The interrelation between the isosubstituent and the isokinetic relationship is developed and tested for several Hammett reaction series. Two methods of approach to relate the temperature dependence of Arrhenius and Hammett plots are given, one utilizing the isoequilibrium temperature of the ionization of benzoic acids and the other the isokinetic temperature of the respective Hammett reaction series. The efficiency of the approaches for the evaluation of the coordinates of the common point of intersection in the Hammett plot, i.e. the characteristics of the isosubstituent relationship, are compared with each other and with experimental results. With the former approach, by using the activation parameters of only one (commonly the unsubstituted ) member of the series, the temperature dependence of a Hammett line can be predicted provided that the isokinetic temperature of the Hammett series does not approach the experimental temperature range. Otherwise the latter approach must be used which, however, needs the temperature dependence of at least two (or better more) members of the reaction series.
The Deoxygenation of Some Carbohydrate Diols Via the Derived Cyclic Thiocarbonate
Authors: Patroni JJ , Stick RV , Engelhardt LM , White AH
Published: September 2010

The treatment of methyl 2,6-di-O-methyl-3,4-O-thiocarbonyl-β-D-galactoside with methyl iodide gives mainly the 3-deoxy-3-iodo-D-guloside ,
whereas the α- anomer of the above and methyl 2-O-methyl-3,4- O- thiocarbonyl-β-L-arabinoside give mainly the 4-deoxy-4-iodo-D- glycosides. An explanation is given for these and some previously reported results. As well, two of the above cyclic thiocarbonates (β-D-galacto and β-L- arabino), together with two cyclic thiocarbonates derived from methyl α-D- mannopyranoside, when treated with tributyltin hydride, gave mixtures (nearly 1:1) of products resulting from deoxygenation . Single-crystal X-ray diffraction structure determination of the β-D- galacto and the β-L- arabino cyclic thiocarbonates showed both pyranose rings to be in the 4C1 conformation.
Experiments Directed Towards the Synthesis of Anthracyclinones .11. A New Diels-Alder Entry to (±)-4-Demethoxydaunomycinone
Authors: Boddy IK , Cambie RC , Marsh NF , Rutledge PS , Woodgate PD
Published: September 2010

The cycloaddition of 2-acetoxybuta-1,3-diene to the external double bond of quinizarinquinone proceeds in high yield in benzene at 55°. The resulting adduct has been converted into a key intermediate for 4- demethoxydaunomycinone synthesis.
S-33 and O-17 N.M.R-Studies of Thiomolybdates and Thiotungstates
Authors: Belton PS , Cox IJ , Harris RK , Oconnor MJ
Published: September 2010

Sulfur-33 and oxygen-17 n.m.r . studies are shown to have considerable potential in following the equilibration of the thiometallate anions [MSnO4-n]2- (M = W, Mo; n = 0-4) in aqueous solution. Chemical shift and linewidth data are presented for these ions. Variations in both the oxygen-17 and sulfur-33 shifts can be correlated with the lowest-energy electronic transition. Moreover, changes in the oxygen-17 and sulfur-33 chemical shift data can be correlated with the molybdenum-95 and tungsten-183 chemical shift values, which have been previously reported. The implications for the nature of the bonding in these anions are discussed.
A Novel Anionic Rearrangement of a Cyclohexadienone. A Serendipitous Synthesis of Methyl (E)-3-Isopropyl-6-Oxohept-4-Enoate
Authors: Carman RM , Vandonge n
Published: September 2010

The cyclohexadienone (2b) with methanolic potassium hydroxide provides the two isomeric cyclopentenecarboxylic acid derivatives (5) and (6) together with the acyclic ester (4a).
Rearrangements in the Furan Series. III. Reactions of 2,4-Diarylaminocyclopent-2-Enones With Nucleophiles
Authors: Darcy BR , Lewis KG , Mulquiney CE
Published: September 2010

Alcoholysis of the 4-arylamino group of a number of 2,4-diarylaminocyclopent-2-enones occurs readily to form the 4-alkoxy derivatives. Under suitable conditions a number of other nucleophiles yielded a variety of 4-substituted 2-arylaminocyclopent-2-enones. As by-products of these reactions several compounds having a novel tetracyclic structure were isolated.
Synthesis of 6-(3,4-Dimethoxyphenyl)-4-oxo-3,4-dihydrobenzo[C][2,7]naphthyridin-6-ium Chloride (Perloline Chloride)
Authors: Ridley AB , Taylor WC
Published: September 2010

Perloline was synthesized as its chloride, 6-(3,4-dimethoxypheny1)-4-oxo-3,4-dihydrobenzo-[c][2,7]naphthyridin-6-ium chloride (lb), by utilizing the photochemical rearrangement of the N-oxide (6) of 5-(3,4-dimethoxyphenyl) benzo [c][2,7]naphthyridin-4(3 H)-one (2) to 6-(3,4-dimethoxyphenyl ) benzo [c][2,7]naphthyridine-4,5(3 H,6 H)- dione (7) ( dehydroperloline), which was then selectively reduced with sodium bis( methoxyethoxy ) aluminium hydride. The naphthyridinone (2) was prepared conveniently by reaction of 2-(3,4-dimethoxypheny1)-4-methylquinoline-3-carbonitrile (4) with dimethylformamide dimethyl acetal, and cyclization of the enamine product (5) with polyphosphoric acid.
Structure and Conformations of GABA-Transaminase Inhibitors. III. Synthesis and Crystal Structure of a Novel Tetracyclic Benzoxazaborinone
Authors: Andrews PR , Gulbis JM , Iskander MN , Mackay MF
Published: September 2010

Reduction of the substituted Schiff base (1) with sodium borohydride gave a product which was found by X-ray crystallographic analysis to be a mixture of two unexpected tetracyclic benzoxazaborinones (3a,b). X-ray analysis showed that, in the dipolar molecules, the pyridine nitrogen is protonated and the boron carries the negative charge. The crystals have site disorder, the exocyclic attachment at the boron being 73% methoxy (3a) and 27% hydroxy (3b). The stability, conformational rigidity and potential biology activity of these cyclic boron chelates all combine to give them particular interest as targets for further chemical and biological studies.
Selective O-Demethylation of 5,8-Dihydroxy-2,3-Dimethoxy-6-Methylnaphtho-1,4-Quinone: The Crystal Structures of 5,8-Dihydroxy-2,3-Dimethoxy-6-Methylnaphtho-1,4-Quinone and 2,5,8-Triacetoxy-3-Methoxy-6-Methylnaphtho-1,4-Quinone
Authors: Cannon JR , Matsuki Y , Patrick VA , White AH
Published: September 2010

It has been confirmed that treatment of 5,8-dihydroxy-2,3-dimethoxy-6-methylnaphtho-1,4- quinone (1) with dilute aqueous sodium hydroxide leads to selective O- demethylation. The hydrolysis product has been identified as 2,5,8-trihydroxy-3-methoxy-6-methylnaphtho1,4- quinone (3) from the crystal structure of the corresponding triacetate (4). The crystal structures of 5,8-dihydroxy-2,3-dimethoxy-6-methylnaphtho-1,4-quinone (1) and 2,5,8-triacetoxy-3-methoxy-6-methylnaphtho-1,4-quinone (4) were determined by X-ray diffraction; diffractometer data at 295 K were refined by least squares techniques to residuals of 0.074 (583 'observed' reflections) for (1) and 0.049 (2005) for (4). Crystals of (1) are monoclinic, P2l/c, a 3.873(4), b 20.21(1), c 15.OO(2) �, β 96.05(6)�, Z 4. Crystals of (4) are also monoclinic, P2l/c, a 10.532(5), b 14.596(6), c 12.097(6) �, β 109.74(4)�, Z 4.
The Chemistry of Laurenene. VI. An Investigation of the Widely Differing Reactivity of a Pair of Epimeric Keto Esters
Authors: Hanton LR , Lorimer SD , Weavers RT
Published: September 2010

X-ray crystallography and two-dimensional n.m.r. techniques have been used to establish the conformations of the epimeric keto esters (1) and (3), derived from cleavage of ring A of lauren-1-ene (2). This information has been used to rationalize the disparate reactivity of the keto functions of (1) and (3) in acid-catalysed carbocation rearrangements and with lithium aluminium hydride. The structures of two new rearranged ethers derived from (1) are also discussed.
Phenolic Analogs of Amino Carboxylic-Acid Ligands for Tc-99m. 1. Synthesis and Characterization of N,N'-Ethylenebis[2-(-O-Hydroxyphenyl)Glycines] (Ehpg)
Authors: Wilson JG
Published: September 2010

Nine N,N'- ethylenebis [2-(o- hydroxyphenyl ) glycines ] ( ehpg ) have been prepared and characterized by conversion into their dimethyl ester dihydrochlorides. Their i.r ., 1H n.m.r. and f.a.b. mass spectral data are presented and discussed.
Crystal and Molecular Structure of Triaqua-tri-μ-chloro-hexachloro-triangulo-trirhenium(III)-Bis[4,6-dimetylpyrimidine-2(1H)-thione hydrochloride]-Dihydrate
Authors: Battaglia LP , Corradi AB , Battistuzzi R , Manfredini T
Published: September 2010

Reaction between rhenium(III) chloride and 4,6-dimethylpyrimidine-2(1H)- thione hydrochloride in concentrated HCl solution results in the formation of [Re3C19(H2O)3].2(C6H7N2S.HCl).-2H2O. The compound crystallizes in the orthorhombic space group Pnma with cell dimensions a 16.797(4), b 21.917(4), c 9.514(1) � and Z 4. The structure was solved by the heavy-atom method and refined by least-squares calculations to a final R value of 0.0517 (R' 0.0602). The structure consists of discrete [Re3Cl9(H2O)3] units, protonated organic molecules, chloride ions, and water molecules. In the cluster three rhenium atoms are linked to form a triangle, with chlorine atoms bridging each pair of rheniums which present short Re-Re bonds [2.440(1), 2.433(1) and 2.444(1) �]. Three water molecules in the equatorial plane and six chlorine atoms perpendicular to it (three above and three below) make the coordination around each rhenium distorted pentagonal bipyramidal.
Oxygenation of 1-t-Butylcyclohexa-1,3-diene and Cholesta-2,4-diene in the Presence of Trityl Tetrafluoroborate
Authors: Arain MF , Haynes RK , Vonwiller SC , Hambley TW
Published: September 2010

Whereas the oxygenation of 1-t-butylcyclohexa-1,3-diene (4) in the presence of catalytic amounts of trityl tetrafluoroborate in dichloromethane at -78° under irradiation from a tungsten lamp gives two dimeric epidioxides as major products, cholesta-2,4-diene (5) gives under the same conditions a monomeric endoperoxide. The structures of the dimeric epidioxides have been established by a combination of chemical degradation, high-field 1H n.m.r. and an X-ray crystallographic study on the diketone (12) derived from one of the epidioxides. A mechanism involving the generation of intermediate monomer and dimer cation radicals is used to account for the formation of the dimeric epidioxides. The dimer cation radicals are expected to be more reactive than the monomer cation radicals towards oxygen. The dimerization is assumed to take place when the diene (4) and its monomer cation radical are aligned so that one reactant lies above the other whereby π-orbital overlap between the rings is maximized; oxygen is constrained to attack the one exposed face of the allylic radical system in the dimer cation radical. This accounts for the unique stereochemistry of the epidioxide products. Crystal data for diketone (12): a 29.975(4), b 5.767(1), c 11.758(2)Ǻ, β 111.67(2)°; C2/c; Z4.
Pyrolysis of Aryl Azides. VIII. Hammett Correlations of Rates of Pyrolysis of Substituted 2-Azidobenzophenones
Authors: Dyall LK , Karpa GJ
Published: September 2010

Eight 2-azidobenzophenones with 4- or 5-substituents have been pyrolysed in decalin solution to yield 3-phenyl-2,1-benzisoxazoles. Rate values at 100° are correlated with the Hammett substituent constants, with respect to both the azido (A) and benzoyl (B) reaction centres , and yield the equation log k = -4.38 + 2.08σ-/A -1.52σB. There is a similar equation for rates measured at 120°. Although nitro and benzoyl differ considerably in their neighbouring group abilities in azide pyrolyses, it is concluded that they exert their effects through the same mechanism. The results are consistent with both published variants of an electrocyclic mechanism (Dyall; Smith, Budde and Chou).
Synthetic and Characterization Studies of the Complexes [Ru(NH3)3(2-Pyridyl; X = N, COH, CH, P), and the X-Ray Crystal Structure of [Ru(NH3)3(Py3COH)]Br2.H2O
Authors: Moritz PS , Diamantis AA , Keene FR , Snow MR , Tiekink ERT
Published: September 2010

Reaction of molar ratios of the ligands tri(2-pyridyl)amine (Py3N), or tri(2-pyridyl)-methanol (Py3COH) with [ Ru (NH3)3(OH2)3]2+ in aqueous solution produces the respective [ Ru (NH3)3(tripod)]2+ complexes. The analogous reaction with tri(2-pyridyl)methane (Py3CH) yields [ Ru (NH3)2(OH2)(Py3CH)]2+, while the reaction with the tri(2-pyridyl ) phosphine ligand produces several (unidentified) species. The N- and CH-bridged ligands appear coordinated in a tripodal manner through the
three pyridine-N atoms of the ligand , whereas tri(2- pyridyl )-methanol is coordinated in an N,N′,O mode through two pyridine-N atoms and the hydroxy group of the bridge. The X-ray crystal structure of [ Ru (NH3)3(Py3COH)]Br2.H2O confirms this assignment: the complex of formula C16H24Br2N6O2Ru is monoclinic, space group P21/c, with cell dimensions a 13.916(6), b 10.300(2), c 15.910(7)Ǻ, β 111.90(3)°, and Z 4. Full-matrix least-squares refinement on 2062 reflections with 1 ≥ 2.5σ(I) converged to final R 0.030 and Rw 0.035. The coordinated OH group in the complex has a pKa of 6.5(�0.1) at 25°C (aqueous 0.1 mol dm-3 KNO3).
Preparation of Thieno[3,2-e][1,2]oxazepine, Thieno and [1]Benzothieno-[3,2-g][1,4]oxazonine, and 5H-Thieno and 1H-[1]Benzothieno-[3,2-h][1,5]oxazecine Derivatives by Ring Expansion Methods. X-Ray Crystal Structure of 1-Phenyl-1,3,4,5,6,7-hexahydro[1]benzothieno-[3,2-g][1,4]oxazonine-5-carbonitrile
Authors: Bremner JB , Browne EJ , Engelhardt LM , Greenwood CS , White AH
Published: September 2010

10-Phenyl-4,5,6,7,8,10-hexahydrothieno[3,2-g][1,4]oxazonine-6-carbonitrile (6a) and 11-phenyl-4,6,7,8,9,11-hexahydro-5H-thieno[3,2-h][1,5]oxazecine-6-carbonitrile (7a) were prepared in moderate yields by cyanogen bromide-induced ring expansion of tetrahydrothieno [2,3- c] pyridinylalkanol precursors (4a) and (5a), respectively. 1-Phenyl-1,3,4,5,6,7-hexahydro[1]- benzothieno [3,2-g][1,4]oxazonine-5-carbonitrile (6b) and 1-phenyl-3,4,5,6,7,8-hexahydro-1H- [1] benzothieno [3,2-h][1,5]oxazecine-6-carbonitrie (7b) were similarly prepared from the [1] benzothieno [2,3-c] pyridinylalkanol precursors (4b) and (5b). The medium-ring cyanamides (6b) and (7b) were converted by standard methods into their N-methyl analogues (8b) and (9b). 6-Methyl-8-phenyl-4,5,6,8-tetrahydrothieno[3,2-e][1,2] oxazepine (13) was prepared by thermal Meisenheimer rearrangement of the corresponding tertiary amine N-oxide (12). The compounds (6a, b), (7a, b) and (13) are each the first reported examples of new heterocyclic systems. The crystal and molecular structure of (6b) has been determined by X-ray crystallographic methods.
The Chemistry of Phthalidecarboxylic Acid. IV. Michael Additions to Conjugated Ketones
Authors: Heisler T , Janowski WK , Prager RH , Thompson MJ
Published: September 2010

Michael additions of methyl 3-oxo-1,3-dihydroisobenzofuran-1-carboxylate to conjugated ketones are reported. The use of amine catalysts gives only the kinetic product; the use of cinchonine and cinchonidine gives a single diastereoisomer with 67% enantiomeric excess and of opposite chirality respectively. The use of lithium diisopropylamide gives 4-oxotetrahydronaphthalenes which react with aqueous base to give the thermodynamic diastereoisomer of the Michael adduct.
Potential Inhibitors of Phosphoenolpyruvate Carboxylase. II. Phosphonic Acid Substrate Analogs Derived From Reaction of Trialkyl Phosphites With Halomethacrylates
Authors: Mcfadden HG , Harris RLN , Jenkins CLD
Published: September 2010

Analogues of phosphoenolpyruvate (PEP), the substrate of PEP carboxylase , were synthesized as potential inhibitors of the enzyme. Esterified analogue precursors were obtained by nucleophilic substitution of various halomethacrylate derivatives with trialkyl phosphites. Substitution of the halomethacrylates can occur either α to the leaving halogen or in the γ position with subsequent allylic shift of the double bond. The course of the reaction was influenced both by reaction conditions and the nature of the substituents on the reactants. The phosphonomethacrylates obtained were hydrolysed to PEP analogues that were found to be moderate to good inhibitors of PEP carboxylase. Phosphonomethacrylic acid derivatives bearing two halogen substituents in the γ position were found to be the most potent inhibitors of this enzyme.
Chelation and Hydrolysis of Orthophosphate Coordinated to Cobalt(III). Reactions of [Co(en)2(O2PO2)] Under Alkaline Conditions
Authors: Buckingham DA , Clark CR , Stewart I
Published: September 2010

Ring opening and closing under alkaline conditions of the four-membered orthophosphate chelate [Co(en)2(O2PO2)] has been followed by both visible absorption and 31P n.m.r. spectroscopy. The former reaction follows the rate law khyd = k2+kl[OH-] with k2 = 2.2 × 10-5 s-1 and k1 = (1.63 � 0.04)×10-2 mol-1 dm3 s-1, and ring closure the rate law kch = k-2 + k-1 with k-2 = 6×10-4 s-1 for cis -[Co(en)2(OH)(OPO3H)1 and k-1 = 7.5×10-5 s-1 for cis-[Co(en)2(OH)(OPO3)]-, all at 25°C and I = 1.0 mol dm-3 (NaNO3).trans- Monodentate species adopt higher concentrations than cis-monodentate species at equilibrium under all alkaline conditions.
Crystal and Molecular Structures of Two Isomorphous Solvates of the Macrolide Antibiotic Borrelidin: Absolute Configuration Determination by Incorporation of a Chiral Solvent in the Crystal Lattice
Authors: Anderson BF , Herlt AJ , Rickards RW , Robertson GB
Published: September 2010

Crystal structures of two isomorphous solvates of the macrolide antibiotic borrelidin [ borrelidin 3-methylbutan-1-ol (A) and borrelidin (S)-2-methylbutan-1-ol (B)] have been determined from X-ray diffractometer data recorded at 294 and 152 K respectively. Crystals are monoclinic, space group P21, with a 13.501(2), b 12.000(2), c 11.863(2) � , β 110.76(1)� [(A); T = 294 K], and a 13.565(2), b 11.646(2), c 11 .376(3) �, β 109.76(1)� [(B); T = 152 K], (Z = 2). The structures were solved by direct-methods procedures and refined by full-matrix least-squares analysis to conventional R-factors of 0.061 [(A), 2676 reflections] and 0.048 [(B), 2851 reflections]. The absolute configuration of borrelidin follows from the known chirality of the (S)-2-methylbutan-1-ol solvent in (B), and is 3S,4S,6S,8R,1OS,11R,17S,18R,22R. The unusual structural and stereochemical features of borrelidin are discussed in relation to other macrolide antibiotics.
Ethoxycarbonylation of α-Cyano-o-toluonitrile and Cyclization to Isoquinolines and Pyrimido[4,5-c]isoquinolines
Authors: Deady LW , Ganakas AM , Ong BH
Published: September 2010

α -Cyano-o-toluonitrile is a-ethoxycarbonylated with ethyl chloroformate and 4-dimethylamino- pyridine, and cyclized to ethyl 3-amino-1-bromoisoquinoline-4-carboxylate. This is further functionalized, and examples of third-ring annulation to pyrimido [4,5-c] isoquinolines are reported.
Enolic Ortho Esters. I. Preparation and Birch Reduction of Some Coumarinoid Ortho Esters
Authors: Collins DJ , Downes LM , Jhingran AG , Rutschmann SB , Sharp GJ
Published: September 2010

Phenolic ortho esters such as 4′,4′-dimethylspiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (7b) and 4′,4′-dimethyl-3,4-dihydrospiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (9c) were prepared in low yields by reaction of 2H-1-benzopyran-2-one (5) or 3,4-dihydro-2H-1-benzopyran-2-one (8a) with 2,2-dimethyloxiran in carbon tetrachloride in the presence of boron trifluoride etherate. 3,4-Dihydrospiro[2H-1-benzopyran-2,2′-[1,3] dioxoan ] (9a) and the corresponding 7-methoxy compound (9e) were obtained in high yield by reaction of (8a) or its 7-methoxy analogue (8b) with 1,2-bis(trimethylsily1oxy)ethane (10) in the presence of trimethylsilyl trifluoromethane-sulfonate . Birch reduction of phenolic ortho esters such as (9c) and (9e) afforded the enolic ortho esters 4′,4′-dimethyl-3,4,5,8-tetrahydrospiro[2H-1-benzopyran-2,2′-[1,3] dioxola n] (11a) and 7-methoxy-3,4,5,8-tetrahydrospiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (llc) in high yields. Birch reduction of 4′,4′,5′,5′-tetramethylspiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (7c) gave a 1 : 3 mixture of 4′,4′,5′,5′-tetramethyl-3,4-dihydrospiro[2H-1-benzopyran-2,2′-[l,3] dioxolan ] (9d) and the corresponding 3,4,5,8-tetrahydro compound (11b). Acid hydrolysis of the enolic ortho ester (11a) gave 67% of 2-hydroxy-2-methylpropyl 3-(2-oxocyclohex-3-enyl) propanoate (20).
New Hopane Triterpenoids From Lichens in the Family Physiaceae
Authors: Wilkins AL , Elix JA , Gaul KL , Moberg R
Published: September 2010

Three new hopane triterpenes have been isolated from lichens of the family Physciaceae. Two of the triterpenes, 22-hydroxyhopan-6-one (2) and 6 α-acetoxyhopan-22-ol (1b), have been characterized previously but their natural occurrence is reported for the first time, while a new triterpene acid [ aipolic acid (1c)], was isolated and characterized as the corresponding methyl ester. One- and two-dimensional 1H-1H and 13C-lH correlated n.m.r. studies have revealed methyl aipolate to be methyl 6#945;-acetoxy-22-hydroxyhopan-25-oate (1d).
Tropical Marine Algae. IV. Novel Metabolites From the Red Alga Laurencia implicata (Rhodophyta, Rhodophyceae, Ceramiales, Rhodomelaceae)
Authors: Coll JC , Wright AD
Published: September 2010

The marine alga Laurencia implicata afforded four new C15-lipid' type metabolites: (3Z,6Z,9Z)-12-bromo-5,13-epoxypentadeca-3,6,9-trien-1-yne (6) with an unprecedented 1-oxacyclodecane ring, (3Z,6Z,92)-13-bromo-5,12-epoxypentadeca-3,6,9-trien-1-yne (7) with a nine-membered ether ring, (3E,6S,7S,9S,10S,12S,13R)-10,12-dibromo-6,9:7,13-bisepoxy-pentadec-3-en-l-yne (8), in which a chlorine atom in the known compound chlorofucin (9) has been replaced by bromine, (1R*,4R*,6S*,7S*)-9-acetoxy-1,10,12-tribromo-4,7:6,13-bisepoxypentadeca-1,2-diene (11) and the closely related known metabolite neolaurallene (10). In addition, a brominated sesquiterpene (1'R*,3′R*)-2-(3?-bromo-1′,2′,2′-trimethylcyclopentyl-5-methylphenol (14), The 2′-hydroxy derivative of α- bromocuparene (15), was identified. Structural elucidation of all metabolites was based on high-field n.m.r. studies and comparison with known metabolites.
Enolic Ortho Esters. IV. Synthesis of the 8-α and 8-β Epimers of a 6-Oxa Steroidal Enolic Ortho Ester
Authors: Collins DJ , Jhingran AG , Rutschmann SB
Published: September 2010

Reaction of resorcinol (9) with methyl 1β-hydroxy-7aβ-methyl-5-oxo-2,3,3 a α,4,5,6,7,7a- octahydro-1H-indene-4α-carboxylate (10a) or with the corresponding 1,5-dioxo ester (15) in methanesulfonic acid gave ( �)-3,17 β-dihydroxy-6-oxaestra-l,3,5(10),8(9)-tetraen-7-one (11a) (98%), or (c)-3-hydroxy-6-oxaestra-1,3,5(10),8(9)-tetraene-7,17-dione (14) (91%), respectively. 3-O-Methylation of the phenolic keto lactone (14) followed by reaction with ethylene glycol gave (�)-17,17-ethylenedioxy-3-methoxy-6-oxaestra-1,3,5(10),8(9)- tetrae n-7-one (16). Reduction of this with lithium/ammonia afforded 77% of (�) 17,17-ethylenedioxy-3-methoxy-6-oxa-8 α-estra-1,3,5(10)-trien-7-one (71, which upon base-catalysed epimerization yielded 84% of the 8 β-epimer (19). Reaction of the 8 α-H lactone (17) or its 8 β- epimer
(19) with ethylene oxide in the presence of boron trifluoride etherate yielded the corresponding phenolic ortho esters (�)-7,7:17,17-bis( ethylenedioxy )-3-methoxy-6-oxa-8 α-estra-1,3,S(10)- triene (23), and its 8 β- epimer (25), in 36 and 42% yields, respectively. Birch reduction of (23) and (25) afforded the corresponding enolic ortho ester ( �)-7,7:17,17-bis( ethylenedioxy )-3-methoxy-6-oxa-8 α-estra-2,5(10)- diene (26), and its 8 β-epimer (6), in 82 and 64% yields, respectively. Some related chemistry is described. The enolic ortho esters (26) and (6) were relatively inert to attack by methylmagne sium iodide under normal conditions.
Facile Synthesis of β-Phenylethylamine Derivatives Related to Baclofen via Aziridine Ring Opening
Authors: Allan RD , Tran HW
Published: September 2010

Nucleophilic ring opening of the protonated salt of 2-(4-chlorophenyl ) aziridine with substituted thiols provides a very simple route to β- phenylethylamine derivatives which are analogues of the GABAB receptor agonist baclofen and its antagonists phaclofen and saclofen.
Alkaloids of Templetonia retusa. Chemistry, Structure and Absolute Configuration of (-)-Templetine
Authors: Cannon JR , Williams JR , Arbain D , Brossi A , Blount JF , Raston CL , Skelton BW , White AH
Published: September 2010

(-)-Cytisine, (+)-lupanine, (-)-anagyrine, (�)-piptanthine and (-)-templetine have been isolated from Templetonia retusa (Vent.) R.Br. The absolute crystal structures of the trihydrochloride dihydrate and the isomorphous trihydrobromide dihydrate of (-)- templetine have both been determined by single-crystal X-ray diffraction; diffractometer data at 295 K were refined by least-squares techniques to residuals of 0.045 and 0.031, respectively, for 2351 and 1948 'observed' reflections. Crystals of the trihydrochloride are orthorhombic P212121, a 8.830(4), b 14.201(6), c 19.122(12)Ǻ, Z 4. Crystals of the trihydrobromide are isomorphous, a 9.081(3), b 14.578(2), c 19.197(11)Ǻ, Z 4. The absolute structure (1) of (-)- templetine has led to the absolute structure of its dehydrogenation product (-)- dehydropiptanthine perchlorate (7) which, in turn, has allowed the absolute structures of (-)- ormosanine (6), (+)- piptanthine (4) and (-)- panamine (9) to be defined. (-)- Templetine (1) reacts with formaldehyde to form homotempletine (12) and with carbon disulfide to yield the thiourea (13). Treatment of either (12) or (13) with W-1 Raney nickel followed by perchloric acid has yielded the diperchlorate (15). The X-ray crystal structure of the diperchlorate (15) has also been determined: diffractometer data at 295 K were refined by least-squares techniques to a residual of 0.056 (1312 'observed' reflections). Crystals of the diperchlorate (15) are orthorhombic, P212121, a 18.636(5), b 12.569(6), c 10.403(4)Ǻ, Z 4.
Potential Antimalarials. XIV. Mono-Mannich Bases of 4-[7'-Bromo (and trifluoromethyl)-1',5'-naphthyridin-4'-yl-amino]-5,6,7,8-tetrahydronaphthalen-1-ols
Authors: Barlin GB , Jiravinyu C , Yan JH
Published: September 2010

The mono- Mannich bases 2-diethylaminomethyl-, 2-t-butylaminomethyl-, 2-(pyrrolidin-1-ylmethyl)-, 2-(piperidin-1-ylmethyl)-, 2-(3-and 4-methylpiperidin-1-ylmethyl)-, 2-(4-benzylpip- eridin-1-ylmethyl)- and 2-(4-benzylpiperazin-1-ylmethyl)-4-[7-bromo (and 7-trifluoromethyl)- 1,5-naphthyridin-4-ylamino]-5,6,7,8-tetrahydronaphthalen-1-ols have been prepared from 4- acetamido-5,6,7,8-tetrahydronaphthalen-1-ols by Mannich reactions followed by hydrolysis to the 4-amino compounds and condensation with the relevant 4-chloro heterocycle. The antimalarial activities of these compounds against the chloroquine -sensitive isolate (FCQ-27) of Plasmodium falciparum in vitro are reported; 4-(7-bromo-1,5-naphthyridin-4-yl)amino-2-(t- butylaminomethyl )-5,6,7,8-tetrahydronaphthalen-1-ol was about twice as active as chloroquine . In in vivo tests against Plasmodium vinckei vinckei in mice this compound exhibited significant activity. The 7-bromo compounds were more active than their 7-trifluoromethyl analogues.
Application of a Chemical Thermodynamic Model to the Gibbs Free Energy of Aqueous Electrolyte Solutions. New Equations for the Activity and Osmotic Coefficients
Authors: Leyendekkers JV
Published: September 2010

The chemical thermodynamic (CT) model, based on the extended Tait equation, has been applied to the Gibbs free energy of aqueous solutions of sodium chloride and potassium chloride at 25°C. Equations for the activity and osmotic coefficients were derived. These are made up of the Debye-Huckel limiting slope term, a van der Waals co-volume effect term covering short-range repulsion, a term covering the water compression by the solute and a short-range attractive term. The distance of closest approach derived from the model is the same as that expected for the van der Waals effect. The individual components of the partial molal free energy, that is, the effects of solute concentration on the water and solute respectively, have been calculated.
The Preparation and Crystal Structure of Ammonium Bis[citrato(3-)]cuprate(II)
Authors: Bott RC , Sagatys DS , Lynch DE , Smith G , Kennard CHL , Mak TCW
Published: September 2010

The copper(II) complex with citric acid (NH4)4 [Cu(C6H5O7)2] has been prepared, and its structure determined by X-ray diffraction, giving a residual R 0.035 for 1208 observed reflections. Crystals are monoclinic, space group P21/c with Z 2 in a cell of dimensions a 8.755(3), b 13.185(4), c 9.364(2)Ǻ, β 113.73(2)°. The complex is a centrosymmetric six-coordinate monomer which is isomorphous with ammonium zinc(II) citrate. However, the Cu-O(hydroxyl) bonds [2.341(3)Ǻ] show Jahn-Teller distortion relative to the Cu-O(carboxyl) bonds [1.969(3) and 1.977(3)Ǻ].
Structure of an Ultraviolet Absorber: 2-(3'-t-Butyl-2'-hydroxy-5'-methylphenyl)-benzotriazole
Authors: Greenwood RJ , Mackay MF , Wilshire JFK
Published: September 2010

The 5′-methyl derivative (1) of 2-(2′-hydroxyphenyl) benzotriazole is an effective ultraviolet absorber, the planar molecule having a strong intramolecular (OH…N) hydrogen bond which is considered responsible for its high photostability. X-Ray analysis of the title compound (2) has shown that the introduction of a bulky t-butyl substituent ortho to the phenolic hydroxyl group results in a stronger intramolecular interaction; the OH…N spacing of 2.568(4) � is shorter than that [2.616(2) � previously reported for compound (1).
Molecular Cocrystals of Carboxylic Acids. IX. Carboxylic Acid Interactions With Organic Heterocyclic Bases. The Crystal Structures of the Adducts of (2,4-Dichlorophenoxy)acetic Acid With 3-Hydroxypyridine, 2,4,6-Trinitrobenzoic Acid With 2-Aminopyrimidine, and 4-Nitrobenzoic Acid With 3-Amino-1,2,4-triazole
Authors: Byriel KA , Kennard CHL , Lynch DE , Smith G , Thompson JG
Published: September 2010

The cocrystal adducts of a number of carboxylic acids with organic heterocyclic bases have been prepared, and their structures and intermolecular interactions interpreted through X-ray diffraction and infrared spectroscopic techniques. The crystal structures of three of these compounds, the 1 : 1 adducts [{(2,4-dich1orophenoxy)acetic acid)(3-hydroxypyridine)] (1), [(2,4,6-trinitrobenzoie acid)(2-aminopyrimidine)] (2), and [(4-nitrobenzoic acid)(3-amino- 1,2,4-trimole)] (3), have been determined by single-crystal X-ray diffraction and refined to residuals R 0.026, 0.033 and 0.040 for 1814, 1531 and 727 observed reflections, respectively.
δ-Terpineol
Authors: Bull SD , Carman RM
Published: September 2010

An improved and simple synthesis of crystalline δ-terpineol from, β-pinene is reported.
Solvent Effect on the Hammett Reaction Constant of Substituted Benzoic Acids
Authors: Bartnicka H , Bojanowska I , Kalinowski MK
Published: September 2010

Potentiometric titration has been used to measure dissociation constants of 13 monosubstituted benzoic acids in nitromethane, benzonitrile , acetonitrile , propylene carbonate, acetone, N,N-dimethylformamide, dimethyl sulfoxide, methanol and formamide. The reaction constants of the Hammett equation were found to depend on the solvent acidity and basicity expressed by the α and β parameters of Kamlet and Taft. The p values determined earlier in water and ethanol also obey this rule.
Studies Directed Towards Total Syntheses of the Tropoloisoquinoline Alkaloids Grandirubrine and Imerubrine. I. Preparation of Two 4,5,6-Trimethoxycyclopent[ij]isoquinolin-7-ones and Their Response to Robinson Annulation Conditions
Authors: Banwell MG , Bonadio A , Turner KA , Ireland NK , Mackay MF
Published: September 2010

In connection with efforts to develop total syntheses of the tropoloisoquinoline alkaloids grandirubrine (1) and imerubrine (2), preparations of tricyclic ketone (8) and the related ethoxycarbonyl system (47) are described. Of the various approaches to (8) which were investigated, that proceeding from the known 8-bromo-5,6,7-trimethoxyisoquinoline (27) proved most efficient. Thus, conversion of (27), over three steps, into the Reissert anion (37), followed by alkylation of the latter with methyl iodide or ethyl bromoacetate, afforded (38) and (46), respectively. Treatment of compound (38) with sodium ethoxide resulted in regeneration of the isoquinoline nucleus and provided the C1-substituted compound (40). Upon reaction with lithium diisopropylamide, isoquinoline (40) underwent Dieckmann-type cyclization to give compound (8). A similar reaction sequence involving diester (46) afforded enamine (47), the X-ray crystal structure of which is reported. Efforts to effect Robinson annulation of (8) or (47) with methyl vinyl ketone (or a synthetic equivalent), and thereby produce the tetracyclic compound (10), have been unsuccessful.
Triorganophosphinegold(I) Carbonimidothioates
Authors: Hall VJ , Siasios G , Tiekink ERT
Published: September 2010

The title compounds, R3PAuSC(= NPh )OR′, R = Et, Ph or Cy and R′ = Me, Et, Pr, Pri or Cy, have been prepared and characterized by spectroscopic methods ( i.r., 1H and 13C n.m.r. and f.a.b . m.s .) and, in the case of the R = Ph and R′ = Me compound, by single-crystal X-ray diffraction methods. The spectroscopic data are consistent with the R3PAu moiety being coordinated by the sulfur atom of the thiolate ligand. This has been confirmed by an X-ray study on Ph3PAuSC(= NPh )OMe which shows the gold atom to be linearly coordinated by the phosphorus and sulfur atoms; Au-P(1) 2.258(1), Au-S(1) 2.301(1) Ǻ and P-Au-S 177.7(1)°. Crystals of Ph3PAuSC(= NPh ) OMe are triclinic, space group pī, with unit cell dimensions: a 10.825(1), b 12.553(2), c 8.914(2) Ǻ, α 97.86(2), β 93.79(1), γ 88.60(1)°, V 1197.1 Ǻ3, Z 2. The structure was refined by a full-matrix least-squares procedure to R 0.028 for 4409 reflections with I ≥ 2.5σ(I).
Synthesis of Pyrazoles and Pyrazolo[1,5-a]pyrimidines From 3-Arylsulfonylaminoacrylates
Authors: Mcfadden HG , Huppatz JL , Halladay PK
Published: September 2010

3-Arylsulfonylaminopyrazole-4-carboxamides and -carboxylates were synthesized from 3-arylsulfonylamino-3-methylthiocyanoacrylate derivatives as potential herbicidal inhibitors of the enzyme acetohydroxyacetic acid synthase (AHAS). Some of these compounds were reacted further with acetylacetone, giving 3-arylsulfonylaminopyrazolo[1,5-a]pyrimidine-3-carboxamides by a novel route. During the synthesis of the 3-arylsulfonylaminopyrazole-4-carboxylates, the arylsulfonylamino group was observed to function as a leaving group. This phenomenon is of potential synthetic utility and was found to be sensitive to solvent and steric factors and was also observed with a methylsulfonylamino group. None of the compounds tested was biologically active.
Structural Characterization of Encapsulation Reactions Based on the Tris(ethane-1,2-diamine)cobalt(III) Ion
Authors: Clark IJ , Geue RJ , Engelhardt LM , Harrowfield JM , Sargeson AM , White AH
Published: September 2010

On the basis of structural comparisons involving intermediates and side products of encapsulation reactions as well as several cage complexes, the efficiency of the base- catalysed reaction between formaldehyde, nitromethane and [Co(en)3]3+ (en = ethane-1,2-diamine) to give [Co((NO2)2sar)]3+ appears to be explicable in terms of the 'interlocking' of constituent parts without appreciable concomitant bond length or bond angle distortions. Thus, the structures of the podand ligand complexes Λ-[Co(NO2sen)]Cl3.2H2O [orthorhombic, space group P 212121, a 18.755(6), b 11.598(4), c 9.164(3) Ǻ; R 0.038 for No 1735 'observed' reflections] and Δ,Λ-[Co(Nt-Me,NO2sen)]Cl3.4H2O [monoclinic, P21/n, a 18.613(5), b 9.301(3), c 13.779(4) Ǻ, β 107.10(2)°; R 0.051 for No 26441 show very close configurational and conformational similarities to those of the cage complexes Δ,Λ-[Co(NO2azasar)]Cl3.3H2O [monoclinic, P 21/c, a 9.339(3), b 15.479(9), c 17.360(7)Ǻ, β 114.15(3)°; R 0.048 for No 2612], Δ,Λ-[Co((NO2)2sar)]Cl3.2H2O [triclinic, Pī , a 13.592(3), b 10.024(3), c 9.772(3)Ǻ, α 62.89(2),β 82.96(3), γ 85.15(2)°; R 0.045 for No 5646] and Δ,Λ-[Co((OH)2sar)]Cl3.3H2O [monoclinic, P21/c, a 15.97(1), b 8.758(4), c 16.760(4)Ǻ, β 98.72(4)°; R 0.052 for No 2400], as well as to published structures of [Co(en)3]3+, [Co(tame)2]3+ [tame = 1,1,1-tris- ( aminomethyl )ethane = ethylidynetris ( methanamine )] and other cage complexes. Some of these similarities may be associated with common hydrogen-bonding patterns in the solids resulting from anion ' chelation' by adjacent NH moieties in the metal ion coordination spheres. Necessary caution in relating structural and electronic properties is implied by the structure determination for Δ,Λ [Co(Cl,ClCH2absar)](NO3)3 [monoclinic, P 21/c, a 14.750(6), b 9.264(3), c 17.959(7) Ǻ, β 95.80(3)°; R 0.061 for No 1431], one of the products of molecular rearrangement following nitrosation of [Co((NH2)2sar)]3+. Despite marked electronic spectral and electrochemical differences with its parent complex, [Co(Cl,ClCH2absar)](NO3)3 contains cobalt(III) in a coordination environment which remains similar to those in more symmetrical cage complexes.
The Reaction of Tetrachlorocyclopropene With Trimethylsiloxybuta-1,3-dienes: A One-Pot Diels-Alder Route to Trichlorotropones and Trichlorotropolones
Authors: Banwell MG , Knight JH
Published: September 2010

One-pot syntheses of the trichlorinated troponoid compounds (8), (10), (12) and (18) have been achieved by reacting tetrachlorocyclopropene (5) with various trimethylsiloxybuta-1,3-dienes.
A Short, Regiocontrolled Total Synthesis of the Mold Metabolite Stipitatic Acid
Authors: Banwell MG , Dupuche JR
Published: September 2010

The commercially available cis-1,2-dihydrocatechol (3) has been converted, via the σ-homo-benzoquinone (4b), into the title compound (1).
Structural Systematics of Rare Earth Complexes. V. The Hydrated 1 : 1 Adducts of 2,2′:6′,2″-Terpyridine With the Lanthanoid(III) Chlorides
Authors: Kepert CJ , Lu WM , Skelton BW , White AH
Published: September 2010

Detailed examination of the strucures of the title salts, (tpy)LnCl3.xH2O, across the totality of the rare earth series shows a remarkable interplay of structural type and detail. The predominant phase is the previously studied monoclinic Cm array, a ≈ 7.5, b ≈ 16.6, c ≈ 9.8 Ǻ, β = 90.2°, V ≈ 2200 Ǻ3, Z = 2 formula units. For the initial members of the series (La → Nd ), x is 8; for Dy → Er and Lu, x = 7 is accommodated within the same lattice, as are intermediate degrees of hydration for Sm → Gd . A second monoclinic phase, P 21/c, a ≈ 11.6, b ≈ 13.9, c ≈ 13.8 Ǻ, β ≈ 92.3°, V ≈ 2200 Ǻ3, Z = 4 formula units, is found for Yb and Lu (x = 7); the same phase but with β acute (a ≈ 11.3, b ≈ 14.5, c ≈ 13.3 Ǻ, β ≈ 82.2°, V ≈ 2140 Ǻ3, Z = 4 formula units) is found for Tm (and Y) (x = 6). A less hydrated binuclear phase, x=1, has also been observed for Sm , a 10.179(3), b 9.928(4), c 9.748(4) Ǻα 112.61(3), β 109.85(3), γ 94.72(3)°, V 829.3 Ǻ3, Z = 1 dimer.
Volumetric Behavior of 2-Methoxyethanol+1,2-Dimethoxyethane Binary Mixtures
Authors: Corradini F , Marchetti A , Tagliazucchi M , Tassi L
Published: September 2010

Thermodynamic interactions in 2-methoxyethanol (component 1)+1,2-dimethoxyethane (component 2) binary mixtures have been studied in terms of the excess molar volume from the densities, measured at 19 temperatures between -10 and 80°C, for nine binary mixtures covering the whole miscibility field expressed by the mole fraction 0 ≤ X1 ≤ 1. Excess molar volumes are discussed in terms of induced conformational changes in each component in the presence of the other. The present findings support a hypothesis about the formation of a solvent-cosolvent complex species which has a well defined 1:1 stoichiometric composition and is thermostable under the experimental conditions.
Reactions of α-Substituted Glycine Derivatives With Stannanes in the Presence of Disulfides
Authors: Easton CJ , Peters SC
Published: September 2010

Reactions of α- bromo -, α- benzoyloxy - and α- methoxy -substituted glycine derivatives with stannanes afforded the corresponding α- centred glycinyl radical, which reacted with di -t-butyl disulfide and diphenyl disulfide by homolytic substitution to give the corresponding α-t- butylthio- and α-phenylthio -substituted glycine derivatives, respectively. The glycinyl radical reacted with dibenzyl disulfide by displacement of benzyl radical to give a mixed disulfide, which was subsequently reduced to the corresponding α- benzylthio-substituted glycine derivative. In related reactions of a cystine derivative the corresponding S-glycinylcysteine derivative was produced, indicating that, while the chemical integrity of disulfide bonds in cystine derivatives is likely to be affected in radical reactions of peptides, the reactions are suitable for exploitation in the synthesis of cross-linked amino acid derivatives.
Experiments Directed Towards the Synthesis of Anthracyclinones. XXII. Novel Cyclopropanation Reactions
Authors: Cambie RC , Dudding SM , Higgs KC , Holroyd SE , Rutledge PS , Woodgate PD
Published: September 2010

Iodine/potassium carbonate induced cyclization of hydroxyanthraquinones with ortho-allyl side chains gives iodomethyldihydrofuran anthraquinones which undergo a novel cyclopropanation reaction on treatment with methanolic potassium hydroxide, e.g. (9) gives (12) in 77% yield, and (10) gives (13) in 62% yield. The scope of the reaction is explored and a number of by-products are identified and, where possible, their formation is rationalized.