bluuebunny/crossref_metadata_2025 huggingface dataset:
1,4-Dinitroimidazole and Derivatives. Structure and Thermal Rearrangement
Authors: Grimmett MR , Hua ST , Chang KC , Foley SA , Simpson J
Published: September 2010

Nitration of 4-nitroimidazole in acetic anhydride/glacial acetic acid gives 1,4-dinitroimidazole. The crystal and molecular structure of this compound have been determined by direct methods. Crystals are orthorhombic; P212121, a 5.853(3), b 9.591(8), c 10.392(5) � , V 583.4(7) � 3 , Dm 1 .76 g cm-1, Dc, 1 .80 g cm-1 (Z = 4); λ 0.71069 � ; T 173 K. The structure was refined to R = 0.048 for 926 reflections [I > 2 σ(1)]. Both 2-methyl-4-nitro- and 5-methyl-4-nitro-imidazoles N-nitrate under the same conditions. When heated in solution at 100-140�C 1,4-dinitro- and 2-methyl-1,4-dinitro-imidazoles rearrange to give C-nitro isomers and some denitration products, but 5(4)-methyl-1,4(5)-dinitroimidazole failed to give identifiable products.
Glycomaurin and Glycomaurrol, New Carbazole Alkaloids From Glycosmis mauritiana (Rutaceae) Bark
Authors: Kumar V , Reisch J , Wickramasinghe A
Published: September 2010

The stem bark of Glycosmis mauritiana contained the acridone alkaloids noracronycine and des-N- methylacronycine, and two new carbazole alkaloids, 3,3,10-trimethyl-3,7-dihydropyrano[2,3-c] carbazole (glycomaurin) and 6-methyl-4-(3′-methylbut-2′-enyl)carbazol-3-ol (glycomaurrol), whose structures were confirmed by synthesis and by cyclization to dihydroglycomaurin respectively. Glycomaurin has a ring system which has not been previously found in nature.
Lewis-Base Adducts of Group 11 Metal(I) Compounds. LVII. Crystal-Structure of Bis(2,6-diacetyl-pyridine)silver(I) Perchlorate
Authors: Silong SB , Engelhardt LM , White AH
Published: September 2010

The synthesis and room temperature structural characterization of the title compound [AgL2]+(C104)-, L= 2,6-diacetylpyridine, are reported. Crystals are orthorhombic, Pcan, a 19.629(7), b 14.603(4) and c 14.469(4) � , Z = 8; R was 0.050 for 1987 'observed' reflections. The structure contains two independent [AgL2]+ species, the central nitrogen atoms of the quasi-tridentate ligands being opposed in the coordination spheres of the silver atoms. Both have crystallographically imposed 2 symmetry; in one, this is normal to the N-Ag-N line [actual bond angle, 175.6(2); Ag-N, 2.316(6), Ag-O, 2.589(7) and 2.522(7) � ], relating the two ligands. In the other, it is coincident; for one ligand Ag-N and Ag-O are 2.285(8) and 2.500(8) � , while for the other the two values are 2.271(8) and 2.543(7) �. The silver-nitrogen distances are appreciably longer than the value of 2.166(4) � found for the [Ag( py )2]+ cation.
Lewis-Base Adducts of Main Group Metal(I) Compounds. XI. Di-μ-iodo-bis(N,N,N′,N″,N″-pentamethyldiethylenetriamine-N,N′,N″-sodium)
Authors: Raston CL , Whitaker CR , White AH
Published: September 2010

The synthesis and structural characterization of the 1:1 adduct of sodium(I) iodide and N,N,N′,N″,N″- pentamethyldiethylenetriamine (pmdeta), a novel coordination complex of sodium(I), is recorded. Single-crystal X-ray structure determination shows the compound to be a �,�′- diiodo-bridged dimer, with the tridentate base making up the five-coordinate environment of sodium: [( pmdeta )NaI2Na( pmdeta )]. Crystals are triclinic, P1, a 10.113(2),b 9.470(2), c 8.793(4) � , α 114.48(2), β 92.09(2), γ 96-65(1)°, Z= 1 dimer ; R was 0.037 for 1837 'observed' reflections.
Two New Bromotyrosine-Derived Metabolites From an Australian Marine Sponge, Aplysina sp
Authors: Xynas R , Capon RJ
Published: September 2010

Two new bromotyrosine-derived secondary metabolites, aplysamine-1 (5) and aplysamine-2 (6), were isolated from an Australian marine sponge, Aplysina sp. The structures were assigned on the basis of detailed spectroscopic analysis, and the tertiary amine salt character was revealed by conversion into the corresponding free tertiary amines. Cooccurring with (5) and (6) were the known antibiotic compounds (+)-aeroplysinin (1) and (3′,5′-dibromo-4′-ethoxy-1′-hydroxy-4′-methoxycyclohexa-2′,5′-dienyl)acetamide (2).
Color and Conformation of Some Derivatives of Benzil in the Solid-State: Crystal-Structures of 2,2′-Dimethoxy- 4,4′-Dimethoxy- , 4-4′Diethoxy- and 4,4'-Dibenzyloxy-benzil
Authors: Cannon JR , Patrick VA , White AH
Published: September 2010

The crystal structures of the colourless 2,2'-dimethoxybenzil (2) and 4,4'-diethoxybenzil (6), the yellow 4,4'-dimethoxybenzi (5), and the yellow polymorph of 4,4'-dibenzyloxybenzil (7) have been determined by single-crystal X-ray studies from diffractometer data at 295 K, and refined by full matrix least-squares techniques to residuals of 0.048 (1281 'observed' reflections), 0.041 (610), 0.052 (662) and 0.043 (2140) respectively. Crystals of 2,2′-dimethoxybenzil (2) are monoclinic, P21/c, a 7.861(4), b 7.991(2), c 21.557(9)�, β90.37(4)�, Z 4. Crystals of 4,4'-dimethoxybenzil (6) are monoclinic C2/c, a 21.912(9), b 4.055(2), c 15.197(5) �,β 102 13(3)� Z 4. Crystals of 4,4′-diethoxybenzil (6) are monoclinic C21/c, a 14.544(7), b 4.781(2), c 22.128(7), β 99.06(3)�, Z 4. Crystals of the yellow modification of 4,4'-dibenzyloxybenzil (7) are monoclinic P21/c, a 19.126(4), b 6.91 1(2), c 16.673(7) � β 99.52(3)�, Z 4. It has been found that there is a correlation between the colour of the crystal and the conformation adopted by the molecule in the solid state with the colourless derivatives of benzil having the aromatic ring planes orthogonal.
Imidazo[1,2-b]pyridazines. VII. Syntheses and Central Nervous System Activities of Some 3-Alkoxy-6-benzyloxy (and methoxy-benzyloxy)-2-phenyl(substituted phenyl or pyridinyl)imidazo[1,2-b]pyridazines
Authors: Barlin GB , Davies LP , Ngu MML
Published: September 2010

A series of 15 3-alkoxy-6-benzyloxy( methoxybenzyloxy )-2-phenyl( sbstitted phenyl and pyridinyl )imidazo[l,2-b]pyridazines has been prepared and each compound tested for its ability to displace 3H-diazepam from rat brain plasma membranes. The results have been compared with data previously obtained for other derivatives of this ring system. Compounds containing 6(o- or m- methoxybenzyloxy ) groups were more effective in the displacement of 3H-diazepam than those with the 6-benzyloxy group; and the most active compound was 2-(p- fluorophenyl )-3-methoxy-6-(m- methoxybenzyloxy )imidazo[l,2 b]pyridazine with IC50 1.5 nM.
The Stereochemistry of Organometallic Compounds. XXXIV. Regioselection in the Hydroformylation of Silylalkenes
Authors: Doyle MM , Jackson WR , Perlmutter P
Published: September 2010

The regiochemistry of hydroformylation of alkenes can be controlled by the use of bulky silyl groups attached to the alkene. Use of the t-butyldiphenylsilyl group leads to almost total regiocontrol and the method has been applied to the synthesis of aldols.
Crossed Aldol Reactions of Dioxolans
Authors: Cambie RC , Rutledge PS , Watson PA , Woodgate PD
Published: September 2010

The crossed aldol reactions of some cyclohexyl and cyclohexenyl dioxolans with the silyl enol ether of cyclohexanone have, in general, been shown to result in directed opening of the acetal. However, only limited stereoselectivity results at the termini of the new carbon-carbon bond.
Tropical Marine-Algae. VI. New Monoterpenes From Several Collections of Chondrococcus hornemannii (Rhodophyta, Gigartinales, Rizophyllidaceae)
Authors: Coll JC , Wright AD
Published: September 2010

Four collections of the red algae Chondrococcus hornemannii( Lyngbye ) Schmitz afforded a range of monoterpenes. Structures of ten new metabolites were elucidated by using high- field n.m.r. spectroscopy techniques including 2.D proton-carbon correlation experiments. The new monoterpenes were: (Z)-3-bromo-8-chloro-6-chloromethyl-2-methylocta-1,6-diene (9,6-hydroxymethyl-2-methylocta-2,8-dien-6-ol (6), (Z)-6-hydroxymethyl-2-methylocta-1,6-diene- 3,8-diol (7), (2)-6-hydroxymethyl-2-methyIocta-2,6-dien-8-ol (8), (2)-8-chloro-6-chloromethyl-3- methoxyocta-1,6-diene (9), (Z)-8-chloso-6-chloromethyl-2-methylocta-l,6-dien-3-ol (10), (2E,62) 8-chloro-6-chloromethyl-1-methoxy-2-methylocta-2,6-diene (11), (2E,6Z)-8-chloro-6-chloromethyl- 2-methylocta-2,6-dien-1-ol (12), (Z)-6-chloromethyl-3,8-dimethoxy-2-methylocta-1,6-diene (13) and its positional isomer (Z)-6-chloromethyl-1,8-dimethoxy-2-methyoca-26-diene (14). Although it is possible that some of the metabolites listed may be artefacts of extraction, circumstantial evidence is offered which suggests that most isolates were present in the plant prior to extraction.
The Synthesis and Reactivity of Cyclic Thiocarbonates Derived From Some Carbohydrate 1,2-Diols
Authors: Patroni JJ , Stick RV , Tilbrook DMG , Skelton BW , White AH
Published: September 2010

The attempted synthesis of several carbohydrate 1,2-diols is reported, together with the transformation of two of these diols into cyclic thiocarbonates, namely 4,6-O-benzylidene-3-O-methyl-1,2-O-thiocarbonyl-a-D-glucose and 3,4-O-isopropylidene-1,2-O-thiocarbonyl-β-D-arabinose. The treatment of these thiocarbonates, and a furanose 1,2-thiocarbonate previously prepared by Mukaiyama, with methyl halides and with tributyltin hydride is discussed. A single-crystal X-ray diffraction study of 3,4-O-isopropylidene-1,2-O-thiocarbonyl-β-D-arabinose is recorded.
A Study of the Terpenoids of the Sponge Euryspongia Sp
Authors: Vanaltena IA , Miller DA
Published: September 2010

The metabolites of the sponge Euryspongia sp. ( Dysideidae ) were investigated. The sponge was shown to contain the previously unknown sesquiterpene epoxides (15) and (16), and three known compounds, dehydrodendrolasin (1), thiofurodysinin acetate (13) and thiofurodysin acetate (14). Based on the spectral data of (1) and the synthetic compounds (1′E)- and (1′Z)-3-(4′,8′-dimethylnon-1-enyl)furan (5) and (6), the structures of 'the cis isomer of dehydrodendrolasin' (2), tetradehydrofurospongian-1 (3) and the related C21 furanoterpene (4) should be reevaluated.
Rate Enhancement of Nickel(II)-pada Complex-Formation in Mixed Sodium Perfluorooctanoate/Octanesulfonate Micellar Solutions
Authors: Reinsborough VC , Stulz TDM , Xiang XY
Published: September 2010

Kinetic studies of the Niaq2+ ion complexation with the bidentate ligand pyridine-2-azo-p-dimethylaniline ( pada ) were conducted by the stopped-flow technique in the presence of mixed micelles of sodium perfluorooctanoate
( spfo ) and sodium octanesulfonate ( sos ). Binding constants for Niaq2+ and pada partitioning between bulk solution and micelles were determined through solubility measurements and the murexide techniques respectively. The molar reaction volume for the surfactant was obtained through the fitting of the kinetic data and partitioning constants to the Robinson equation. It was found that spfo micelles promoted the complexation reaction 400-fold just beyond the critical micelle concentration but this maximum value decreased with sos , NaCl or further spfo addition. The unexpected effectiveness of spfo in rate enhancement is due to its compact micellar reaction volume of 0.16 dm3 mol-1. The kinetic results are consistent with spfo and sos forming separate micelles of pure or almost pure composition.
The Synthesis and Chlorination of Some Pyrimidin-4-ols Having 5-Nitrogen Functionality
Authors: Harnden MR , Hurst DT
Published: September 2010

Syntheses of a number of pyrimidin-4-ols having 5-nitrogen functionality are described. Phosphorus oxychloride/diethylaniline chlorination of 6-amino-2-methylthio-5-nitropyrimidin-4-ol gave the corresponding 6-chloro derivative. However, 2-amino-6-methylthio-5-nitropyrimidin-4-ol failed to yield a 4-chloro derivative under the same conditions. Similar chlorination of 2,5-diaminopyrimidine-4,6-diol gave a poor yield of the 4,6-dichloro product but under these conditions 2-amino-5-benzoylaminopyrimidine-4,6-diol* gave 7-chloro-2-phenyloxazolo[5,4-d]pyrimidin-5-amine. 5-Acetylamino-2-methylthiopyrimidine-4,6-diol yielded 7-chloro-2- methyl-5-methylthiooxazolo[5,4-d] pyrimidine as the major product together with some 5-acetylamino-4,6-dichloro-2-methylthiopyrimidine under the same chlorination conditions.
Prediction of the Rate Coefficient for the F+SOF3 Recombination Reaction
Authors: Pitt IG , Gilbert RG , Ryan KR
Published: September 2010

The pressure dependence of the rate coefficient for the recombination reaction SOF3+F → SOF4 has been calculated by utilizing an RRKM canonical variational approach with a hindered-rotor Gorin potential surface. With no adjustable parameters, the high-pressure recombination rate coefficient is predicted to be c. 1×10-10cm3s-1. It was further established that this rate coefficient is close to its high-pressure limit above c. 100 Pa. These results support the conclusions of an experimental study in which this rate coefficient was measured relative to that of the association reaction between SOF3 and O.
A New Synthesis of Pyrazino[2,3-c]isoquinolines
Authors: Bates MRM , Deady LW , Mackay MF
Published: September 2010

A convenient synthesis of 1-(p-chlorophenoxy )isoquinoline-3,4-diame is described. Condensation with ethyl pyruvate gave entry to the tricyclic title system, and some further nucleophilic displacement reactions of substituent groups are described. The direction of ring closure in the tricycle formation was proved by determining the crystal structure of one of the derivatives; rhombohedral crystals of (3b) belong to the space group R3 with a 21.822(5)Ǻ, α 116.81(2)° and Z 12. Full-matrix refinement using 3093 reflections converged at R 0.085.
Oxidative Cyclization of Diamides by Phenyliodoso Acetate
Authors: Beckwith ALJ , Dyall LK
Published: September 2010

Carboxamides containing a suitably situated nucleophilic group ( carboxamide , N-substituted carboxamide, or hydroxymethyl ) undergo oxidation by phenyliodoso acetate to afford heterocyclic products through internal attack on the initially formed isocyanate. N- Substituted carboxamido groups are the least effective of these internal traps. Phenyliodoso acetate is much superior to lead(IV) acetate for oxidative cyclization of maleamide and various substituted propanediamides, but is not suitable for butanediamide.
The Pyrolysis of Butatrienone Precursors: 3,4-Diazatricyclo[5.2.1.02,6]deca-3,8-diene-endo-cis-2,6-dicarboxylic anhydride and Its 5,5-Diphenyl Derivative
Authors: Anderson MR , Brown RFC , Browne NR , Eastwood FW , Fallon GD , Gan DPC , Pullin ADE , Staffa AC
Published: September 2010

Flash vacuum pyrolysis of the title anhydride (4) gave a poor yield of butatrienone , detected by argon matrix isolation infrared spectroscopy. Similar pyrolysis of the 5,5-diphenyl derivative (8) failed to give diphenylbutatrienone ; the red product (16) is considered to have been formed by dimerization of an intermediate 2H-indenylidenemethanone (15). The crystal structure of (16) has been determined.
Organoamido- and Aryloxo-Lanthanoids. I. The Preparation and Characterization of Some Lanthanoid(II) Organoamides, and the X-Ray Crystal Structure of cis-Bis(Carbazol-9-Yl)Tetrakis(tetrahydrofuran)europium(II)
Authors: Deacon GB , Forsyth CM , Gatehouse BM
Published: September 2010

Reaction of carbazole ( Hcbz ) or 2-phenylindole ( Hpin ) with bis ( pentafluorophenyl )-ytterbium or -europium in tetrahydrofuran ( thf ) gives the complexes M( cbz )2( thf )4 (M = Yb or Eu ) or Yb (pin)2( thf )4. From treatment of lanthanoid metals with bis ( pentafluorophenyl )mercury and 2-phenylindole, 2,3,4,5-tetraphenylpyrrole ( Htpp ) or carbazole , the complexes M(pin)2( thf )4 (M = Yb , Eu or Sm ), M( tpp )2( thf )3 (M = Yb or Sm ) and Yb ( cbz )2( thf )4 have been isolated. Desolvation of M(pin)2( thf )4 under vacuum yields Yb (pin)2( thf ) and Sm (pin)2( thf )3. Oxidation of Sm (pin)2( thf )4 with Hg(C6F5)2 and 2-phenylindole gives Sm (pin)3( thf ). The crystal structure of Eu ( cbz )2( thf )4 shows the complex to be monomeric with distorted octahedral stereochemistry for europium, cis-carbazol-9-yl ligands ({ Eu -N} 2.559 Ǻ), and longer Eu -O bonds (av. 2.600Ǻ) trans to N than mutually trans ({ Eu -O} 2.553Ǻ). Other complexes M(NR2)2( thf )n (NR2 = pin, cbz or tpp ) are considered to be monomeric with five (n = 3) or six (n = 4) coordination.
The Chemistry of Pyrrolic Compounds. LXIII. Synthetic Studies of Petroporphyrins With Fused Six-Membered Ring Systems
Authors: Clezy PS , Prashar JK
Published: September 2010

Several approaches to the synthesis of porphyrins bearing fused six- membered ring systems were explored with the aim of obtaining the petroporphyrin (4a). This was ultimately achieved by an intramolecular cyclization of a porphyrin with a propanoyl chloride side chain in the presence of stannic chloride. Methylation of the intermediate ketone with CH3Li and reduction of the resultant alcohol with NaBH3CN/Znl2 furnished (4a).
The Chemistry of Pyrrolic Compounds. LXIV. Intramolecular Cyclization of Butyric Acid Substituted Porphyrins: Petroporphyrins With Fused Seven-Membered Ring Systems
Authors: Clezy PS , Jenie U , Prashar JK
Published: September 2010

The preparation of a series of porphyrins substituted with butyric acid side chains is described and efforts to achieve the intramolecular cyclization of this substituent are discussed. Attempts to prepare a stable spiro ketone by cyclization onto a β- pyrrolic carbon have not met with success but the synthesis of a seven- membered ring ketone by cyclization onto a meso -carbon has been completed. Reduction of this ketone has led to the synthesis of the petroporphyrin (1d). Some comments are offered concerning the origin of the isomeric petroporphyrin (19a) which bears a methylated six- membered ring sytem fused to the porphyrin macrocycle.
An Oxidative Decarboxylation of 7-Oxopodocarpic Acid Derivatives
Authors: Cambie RC , Craw HM , Rickard CEF , Robertson JD , Rutledge PS , Valu KK , Woodgate PD
Published: September 2010

Treatment of the 7-oxopodocarpic acid derivatives (1) and (3) with 2,3-dichloro-5,6-dicyanobenzoquinone affords the conjugated dienones (5) and (6) directly. The latter compounds have potential as optically active relays for the synthesis of 3-oxygenated diterpenoids . The stereochemistry of an epoxide (7) formed from the dienone (5) has been confirmed by X-ray crystallography.
Stereoselectivity of Sigmatropic Homodienyl [1,5]-Hydrogen Migrations
Authors: Pegg GG , Meehan GV
Published: September 2010

Interactions affecting the transition state conformational preference of substituents (R1) at the migration origin have been extensively examined for a range of diversely substituted alkenylcyclopropane substrates undergoing homodienyl [1,5]-hydrogen migration. A chair cyclohexane -like transition state model (11) best rationalizes the stereoselectivity observed in these cases. Thus, the 1,2-double-bond (E)/(Z) ratio for the rearrangement products is in reasonable agreement with prediction based on ΔG° values for R1 equatorial/axial interconversion in substituted cyclohexanes (at least for cases where R3 = H). For systems incorporating a bulky R3 substituent, a marked increase in stereoselectivity for the (E)-olefin product is observed. In agreement with the proposed transition state model (11), bulky R2 or R4 substituents have negligible effect on the conformational preference of R1.
Rearrangement of Substituted Bicyclo[2.1.1]hex-2-yl Mesylates Under Solvolytic Conditions
Authors: Della EW , Elsey GM , Skouroumounis G
Published: September 2010

When heated in formic acid, methyl 2-mesyloxybicyclo[2.1.1]hexane-2-carboxylate (3) ionizes significantly faster than expected and yields the rearranged isomer (6) essentially quantitatively. The latter, on the other hand, solvolyses at a much reduced rate. These data are interpreted as evidence for the presence in the ester of a favourable mesomeric interaction which largely offsets an otherwise destabilizing inductive effect when the ester is attached to a carbocationic centre. The corresponding cyano mesylates (8) and (29) were found to behave in an analogous manner when exposed to the solvolytic conditions. Heating the related acid mesylate (25) in an aqueous medium leads to the 1,2 hydroxy acid (24), whereas its sodium salt (26) is considerably more reactive and gives the 2,2 hydroxy acid (11). These observations are rationalized on the basis of the greatly enhanced ability of the COO- group relative to a COOH to stabilize an adjacent positively charged centre. The methyl substituent is also found to exert a profound effect on the nature of the solvolysis products. In hot formic acid, for example, 1-methylbicyclo[2.1.1]hex-2-yl mesylate (31) produces the formate (32) in which the substitution pattern is retained. Under milder conditions, however, the ester (31) solvolyses with rearrangement to give the 2,2 formate (33).
Organoamido- and Aryloxo-Lanthanoids. II. Preparation of Tris(2,6-diphenylphenoxo)-lanthanoid(III) Complexes and the X-Ray Structures of Low-Coordinate [Yb(O-2,6-Ph2C6H3)3] Containing an Intramolecular Chelate Yb…π-Arene Interaction, and [Yb(O-2,6-Ph2C6H3)3(thf)2].thf (thf = Tetrahydrofuran)
Authors: Deacon GB , Nickel S , Mackinnon P , Tiekink ERT
Published: September 2010

Bulky monomeric lanthanoid(III) aryl oxides Ln(Odpp)3(Odpp = 2,6- diphenylphenoxide; Ln = Nd, Sm, Er, Yb or Lu) have been prepared by reaction between the lanthanoid metal, Hg(C6F5)2, and HOdpp in tetrahydrofuran (thf), and Yb(Odpp)3 has also been obtained from an analogous reaction of (PhCC)2Hg. Cleavage of Ln(η5-C5H5)3 (Ln = Nd or Yb) with HOdpp also yields Ln(Opdd)3. The aryl oxides have been isolated as [Ln(Odpp)3(thf)2] (Ln = Nd, Sm or Yb) or as the homoleptic complexes Ln(Odpp)3 (Ln = Nd, Er, Yb or Lu). The X-ray crystal structure of [Yb(Odpp)3(thf)2].thf [crystals monoclinic, space group P21/n, a 11.009(4), b 32.134 (7), c 15.498(6)Ǻ, β 96.72(3)°, Z 4; 2785 data refined to R 0.039] shows the complex to have distorted square pyramidal stereochemistry with apical and transoid basal Odpp ligands, (Yb-Odpp) 2.078(9)Ǻ, and transoid basal thf ligands, {Yb-O(thf)} 2.305(8)Ǻ. Similarly, Yb(Odpp)3 [crystals triclinic, space group Pī, a 15.934(2), b 13.563(1), c 10.968(2)Ǻ, α 116.71(1), β 92.90(2), γ 103.38(1)°, Z 2; 6236 data refined to R 0.031] was shown to have a trigonal pyramidal arrangement of oxygen donor atoms [{Yb-O} 2.065(4) Ǻ;{O-Yb-O} 117.5(1)°], a novel intramolecular chelate Yb…π-arene interaction, {Yb...C} 2.978(6)Ǻ, and an agostic Yb…CH interaction.
N.M.R.-Studies of Bond Order in Azulene, Biphenylene and 1,6-Methano[10]annulene
Authors: Collins MJ , Sternhell S , Tansey CW
Published: September 2010

The 4J(H-C-C-Me) coupling constants of methyl-substituted derivatives, probes of bond order, have been used to examine the ground-state π- electron distributions in azulene (1), biphenylene (2) and 1,6- methano [10] annulene (3). The experimental data obtained are in good agreement with theoretical predictions for biphenylene (2) and provide some evidence for π-electron disproportionation towards the five-membered ring in azulene (1). The bond orders in 1,6-methano [10] annulene (3) obtained in this work are at variance with those predicted on the grounds of bond lengths.
6-O-Methylarthothelin and 1,3,6-Tri-O-Methylarthothelin, Two New Xanthones From a Dimelaena Lichen
Authors: Elix JA , Bennett SA
Published: September 2010

6-O-Methylarthothelin (5) (2,4,5-trichloro-1,3-dihydroxy-6-methoxy-8- methyl-9H-xanthen-9-one) and 1,3,6-tri-O-methylarthothelin (7) (2,4,5- trichloro-1,3,6-trimethoxy-8-methyl-9H-xanthen-9-one) have been synthesized and shown to cooccur with norstictic acid, connorstictic acid, atranorin and 2,4,5-trichlorolichexanthone (4) in a Dimelaena lichen.
Studies Directed Towards the Total Synthesis of Anticapsin. X-Ray Crystal-Structure of (1RS,2SR,4RS,5RS,6SR)-5-Hydroxy-2-phthalimido-1-trimethylsilyloxy-bicyclo[2.2.2]octane-2,6-carbolactone
Authors: Crossley MJ , Hambley TW , Stamford AW
Published: September 2010

The relative stereochemistry of methyl 2-phthalimido-1- trimethylsilyloxybicyclo[2.2.2]oct-5-ene-2-carboxylate (9) and its 5,6-epoxide (10), intermediates in a synthetic approach to the amino acid antibiotic anticapsin, were established by the TiCl4-mediated cyclization of (10) to the carbolactone (12); the structure of which was proved by single-crystal X-ray crystallography. Full-matrix least- squares refinement of all atomic parameters with individual isotropic thermal parameters for the hydrogen atoms by using 1446 reflections converged at R 0.036. Crystals of (12) are monoclinic, P21/c, a 12.342(3), b 12.239(2), c 13.405(3) Ǻ, β 99.34(2)°, Z 4.
Constituents of Eupomatia Species. XI. New Eupodienone Lignans From the Flowers of Eupomatia laurina
Authors: Carroll AR , Taylor WC
Published: September 2010

On the basis of spectroscopic evidence, eupodienone-8 and -9, isolated from the flowers of Eupomatia laurina R. Br., are assigned the structures (5R, 7R, 8R)-3′,4-dimethoxy-7,8-dimethyl-2,3-methylenedioxy-6,7,8,9-tetrahydrospiro[5H-benzocycloheptene-5,1′-cyclohexa-2′,5′-dien]-4′-one (9) and (5S,7R,8R)-3′,4-dimethoxy-7,8- dimethyl-2,3-methylenedioxy-6,7,8,9-tetrahydrospiro[5H-benzocycloheptene-5,1′-cyclohex-2′,5′-dien]-4′-one (10) respectively. The products of dienone-phenol rearrangement of these substances are characterized; eupodienone-8 unexpectedly rearranges with aryl group migration. Eupomatenoid-1 and -7, eupodienone-6 and (-)- dihydroguaiaretic acid were also isolated.
Dimethyl cis- and trans-1,2-Dimethylcyclohexane-1,2-dicarboxylate
Authors: Rae ID , Serelis AK
Published: September 2010

1-Methoxy-3-trimethylsilyloxybuta-1,3-diene adds readily to dimethylmaleic anhydride, and the product can be converted into dimethyl cis-1,2-dimethylcyclohex-4-ene-1,2-dicarboxylate (3). The several steps required mean that this route compares unfavourably with direct addition of butadiene to the anhydride. The best route to the cis-diester (3) is cyclialkylation of the dianion from dimethyl 2,3-dimethylbutanedioate with (Z)-1,4-dichlorobut-2-ene. A bismethylation reaction is used to prepare imide (II), which can be converted into the cis-diester (1) only with considerable difficulty, and bismethylation of the dianion formed from dimethyl cis-cyclohex-4-ene-1,2- dicarboxylate gives mainly the trans-diester (8). 13C n.m.r. spectra were useful in distinguishing the isomeric pairs (1) and (2), and (3) and (8).
New Chlorine-Containing Depsidones From the Lichen Phyllopsora corallina var. ochroxantha
Authors: Elix JA , Venables DA , Brako L
Published: September 2010

The depsidones phyllopsorin (2-chloro-4,6-diformyl-3-hydroxy-8-methoxy- 1,9-dimethyl-11H-dibenzo[ b,e ][1,4]dioxepin-11-one (3), chlorophyllopsorin (2,7-dichloro-4,6-diformyl-3-hydroxy-8-methoxy-1,9- dimethyl-11H-dibenzo[ b,e ][1,4]dioxepin-11-one) (4), methyl 2,7- dichloro-psoromate (methyl 2,7-dichloro-4-formyl-3-hydroxy-8-methoxy- 1,9-dimethyl-11-oxo-11H-dibenzo[ b,e ][1,4]dioxepin-6-carboxylate) (5) and methyl 2,7-dichloronorpsoromate (methyl 2,7-dichloro-4-formyl-3,8- dihydroxy-1,9-dimethyl-11-oxo-11H-dibenzo[ b,e ][1,4]dioxepin-6-carb- oxylate ) (6) have been isolated from the lichen Phyllopsora corallina var. ochroxantha. The structures of these metabolites have been established from the spectroscopic properties, degradative studies and by partial synthesis.
Synthesis of Dimethylbutatrienone, (CH3)2C=C=C=C=O, by a Rearrangement-Fragmentation Process and by Direct Elimination
Authors: Brown RFC , Coulston KJ , Eastwood FW , Irvine MJ
Published: September 2010

4-Methylpenta-1,2,3-trien-1-one ( dimethylbutatrienone , Me2C=C=C=C=O) was generated by flash vacuum pyrolysis of precursors derived from 4,4-dimethyl-2-oxotetrahydrofuran-3-ylideneacetic acid (6) and from 4-methylpenta-2,3-dienoic acid (14). Pyrolysis of the mixed trifluoroacetic anhydride and of the acid chloride of (6) and, in poorer yield, of (14) gave 4-methylpenta-1,2,3-trien-1-one which was detected by argon matrix infrared
spectroscopy (Vmax 2224, 2216 cm-1) and by reaction with methanol to form methyl 4-methylpenta-2,3-dienoate. The fragmentation pathway for the derivatives of (6) was established by detection of the initially formed propadienone, 4,4-dimethyl-2-oxotetrahydrofuran-3-ylideneethenone, and also by pyrolysis of the trifluoroacetic mixed anhydride (7.L) and the acid chloride (8-L) of 4,4-dimethyl-2-oxotetrahydro(2-13C)furan-3-ylideneacetic acid. The argon matrix spectra of pyrolysates from (7-L) and (8-L) showed bands at 2182 and 2177cm-1 attributed to 4-methyl(1-13C)penta-1,2,3-trien-1-one. 4,4-Dimethyl-3-methylenedihydrofuran-2-one was prepared in 67% yield by flash vacuum pyrolysis of the acid (6).
Perforatin: a Novel Tetranortriterpenoid From Harrisonia perforata
Authors: Byrne LT , Vantri M , Phuong NM , Sargent MV , Skelton BW , White AH
Published: September 2010

Extraction of the dried leaves of Harrisonia perforata (Blanco) Merr ., (Simaroubaceae) has yielded a novel tetranortriterpenoid ( limonoid ), perforatin (1), of the obacunol class. The structure was determined by a combination of spectroscopic analysis and the X-ray method. Comments are made on the stereochemistry of the related limonoid harrisonin.
Lewis-Base Adducts of Main Group 1 Metal(I) Compounds. XIV. Synthesis and Crystal Structure of a 1 : 1 Lithium(I) Chloride Sulfolane Adduct
Authors: Harvey S , Skelton BW , White AH
Published: September 2010

Crystallization of anhydrous lithium(I) chloride from dry sulfolane yields a colourless crystalline 1 : 1 adduct, characterized by analysis and a single-crystal X-ray structure determination. Crystals are orthorhombic, Pna21, a 10.940(3), b 9.611(4), c 6.576(3)Ǻ, Z= 4 formula units; R was 0.033 for 869 independent 'observed' reflections. The structure is an infinite polymer containing four-coordinate (LiCl2O2) lithium, bridged by Li-Cl interactions and O,O′ sulfolanes. Li- Cl, Cl′ are 2.375(8), 2.309(7), and Li-O, O′ 2.016(7), 1.991(6)Ǻ.
Potential GABAB Receptor Antagonists. IV. Synthesis of 1-[2-Amino-1-(4-chlorophenyl)ethyl]-3-oxo-1,3-dihydro-isobenzofuran-1-yl phosphonic Acid
Authors: Janowski WK , Prager RH
Published: September 2010

The diastereoselective addition of dimethyl 3-oxo-1,3-hydroisobenzofuran-1-ylphosphonate to nitrostyrene and p- chloronitrostyrene is reported, as is the subsequent conversion of the Michael adducts into 1-[2-amino-1-phenylethyl]-3-oxo-1,3-dihydroisobenzofuran-1-ylphosphonic acid, and 1-[2-amino-1-(4-chlorophenyl)ethyl]-3-oxo-1,3 dihydroisobenzofuran-1-ylphosphonic acid respectively.
Synthesis of Casein Related Peptides and Phosphopeptides. XIV. Solid Phase Synthesis of Glu-Ser(P)-Leu Through the Use of Protected Boc-Ser(PO3R2)-OH Derivatives
Authors: Perich JW , Valerio RM , Alewood PF , Johns RB
Published: September 2010

A solid phase method is described for the synthesis of O- phosphoseryl-containing peptides by the use of polystyrene resin (Merrifield) as the peptide support and protected Boc-Ser(PO3R2)-OH derivatives for the incorporation of the phosphorylated seryl residue. The viability of this solid phase approach was demonstrated by the synthesis of HBr.H-Glu-Ser (PO3Et2)-Leu-OH in high yield by the use of Bo -Ser(PO3Et2)-OH in peptide synthesis and subsequent use of HBr/CF3CO2H for cleavage of the Ser(PO3Et2)-containing tripeptide from the resin support. Similarly, the dipeptide, CF3CO2H.H-Ser(P)- Leu -OH, was prepared in high yield by using Boc -Ser(PO3But2)-OH in peptide synthesis followed by the one-step deprotection of the Ser(PO3But2)- dipeptide resin by treatment with HBr/CF3CO2H (90 min). Alternatively, the O-phosphoseryl tripeptide , CF3CO2H.H-Glu-Ser(P)- Leu -OH was prepared by using either Ppoc -Ser(PO3Bzl2)-OH or Boc-Ser(PO3Ph2)-OH in peptide synthesis. The one-step deprotection of the Ser(PO3Bzl2)-containing tripeptide and cleavage of the peptide from the resin support was effected by high-pressure hydrogenolysis (palladium acetate). In the case of phenyl phosphate protection, the Ser(PO3Ph2)-containing peptide was cleaved from the resin support by high-pressure hydrogenolysis (palladium acetate) followed by cleavage of the phenyl phosphate groups by platinum-mediated hydrogenolysis (1.0 equiv. PtO2/phenyl group) in 50% CF3CO2H/AcOH.
Epoxy Lipids From the Australian Epiphytic Brown Alga Notheia anomala. II.
Authors: Murray LM , Barrow RA , Capon RJ
Published: September 2010

Continuation of a study into the chemistry of the brown alga Notheia anomala has resulted in the isolation and structure elucidation of six new C21 lipids. These include the first reported occurrence of a secondary metabolite (3), O-acylated by arachidonic acid, along with three new bisepoxy lipids (4)-(6), and two novel trisepoxy lipids (7) and (8). The structures were secured by detailed spectroscopic analysis and chemical degradation.
Electron-Impact Mass-Spectra of 3-Alkyl-2,1-benzisoxazoles
Authors: Dyall LK , Ferguson JA
Published: September 2010

3-Alkyl-2,1-benzisoxazoles underwent complex fragmentations under electron impact, and the balance between available pathways changed considerably across the range of alkyl groups (methyl, ethyl, isopropyl and t-butyl). The primary loss of CO is accounted for in terms of rearrangement of the initial molecular ion to an alkylimine ketene species. The 3-methyl compounds lost methyl as methyl cyanide, acylium cation or ketene, but the higher alkyl groups were chiefly lost as alkyl cations or by internal fragmentations in which some novel ortho-effects were noted. Most of these pathways were confirmed by B/E linked scans, and useful comparisons were made with the e.i . spectra of N- alkylanthranilic acids. All of these isoxazoles underwent partial decomposition on the heated probe.
Reactions of Coordinated Ligands. The Bromination of 2,4-dimethyl-3H-imidazole and 3H-imidazole Coordinated (at N1) to Pentaamminecobalt(III)
Authors: Blackman AG , Buckingham DA , Clark CR
Published: September 2010

The pH dependence of the bromination of R-2,4-Me2ImH3+ [R=(NH3)5Co] by Br2 in acidic aqueous solution, giving R-2,4-Me2-5-BrImH3+, suggests that proton abstraction from a bromine-substituted Wheland intermediate is rate determining for pH < 3 (both OH-- catalysed and spontaneous paths are observed), while in the pH range 3-5, bromine addition is rate determining. For pH > 5 the reaction may be interpreted to occur through rate-determining Br2 addition to the conjugate base from of the reactant. Rate constants for bromine addition to R-2,4-Me2ImH3+ and R-2,4-Me2Im2+ are respectively 1.1×104 and 3.4×1010 dm3 mol-1 s-1 at 25.0°C, I = 1.0 (NaClO4). Bromination of RimH3+, to give R-4-BrImH3+ initially, appears to occur largely via the conjugate base form of the reactant (k2 = 3.6×109 dm3 mol-1 s-1), but for Ph < 2, addition of Br2 to RImH3+ contributes to the observed rate (k1 = 0.68 dm3 mol-1 s-1). Ea = 61�2 kJ mol-1 for the former process, and the primary kinetic isotope effect, kH/kD, increases from 1.3 in 0.05 M H+ to 2.4 in 5.42 M HClO4. These observations are discussed in terms of diffusion-controlled, or preassociation -type mechanisms.
Structural Elucidation of a Novel Scalarane Derivative by Using High-Field (14.1T) N.M.R. Spectroscopy
Authors: Barron PF , Quinn RJ , Tucker DJ
Published: September 2010

A novel scalarane derivative (2) has been isolated from the marine sponge Carteriospongia foliascens. A complete assignment of the 1H and 13C n.m.r. spectra of (2) was achieved by using cosy-90, 1H-detected 1H/13C correlation (HMQC sequence) and 1H-detected long-range 1H/13C correlation (HMBC sequence) experiments, all measured at 600 MHz. The assignment of stereochemistry at C4 was supported by a ROESY spectrum.
2,5-Dichloro-6-O-Methylnorlichexanthone and 4,5-Dichloro-6-O-Methylnorlichexanthone, Two New Xanthones From an Australian Dimelaena Lichen
Authors: Elix JA , Bennett SA , Hui J
Published: September 2010

2,5-Dichloro-6-O-methylnorlichexanthone (8) (2,5-dichloro-1,3-dihydroxy-6-methoxy-8-methyl-9H-xanthen-9-one) and 4,5-dichloro-6-O-methylnorlichexanthone (9)(4,5-dichloro-1,3-dihydroxy-6-methoxy-8-methyl-9H-xanthen-9-one) have been synthesized and shown to co-occur with norstictic acid, connorstictic acid, atranorin, 6-O-methylarthothelin (4), 2,4,5- trichlorolichexanthone (5), 1,3,6-tri-O-methylarthothelin (6) and thiophaninic acid (7) in an Australian Dimelaena lichen.
Synthesis of Benzannulated Derivatives of Podocarpic Acid
Authors: Cambie RC , Metzler MR , Rutledge PS , Woodgate PD
Published: September 2010

Two cyclopentaannulated derivatives of podocarpic acid have been converted into benzannulated derivatives by a two-step reaction sequence in moderate yield.
Fourier-Transform Infrared Spectroscopic Investigation of the Secondary Structure of P2 Protein in Deuterium Oxide Solution
Authors: Stuart BH , Mcfarlane EF
Published: September 2010

Fourier transform infrared ( F.t.i.r .) spectroscopy has been used to investigate the secondary structure of bovine P2 protein in deuterium oxide (D2O) solution. The amide 1 region of the spectrum was analysed quantitatively by means of resolution enhancement and band-fitting procedures. The protein was found to consist mainly of β-structure (61%), with a small amount of α-helix (11%). A reason for the existence of an unusually intense low-frequency band assigned to β-structure is discussed. The F.t.i.r . results are compared with those from an X-ray crystallographic study and from circular dichroism and explanations are offered for discrepancies between the results from the different methods.
Organoamidometallics. V. Syntheses of [N,N-diethyl-N'-polyfluorophenyl-ethane-1,2-diaminato(1-)]platinum(II) Complexes by Decarboxylation Reactions, and the X-Ray Crystal Structure of trans-[Pt(NC6F5CH2CH2Net2)I(Py)]
Authors: Deacon GB , Gatehouse BM , Ireland J
Published: September 2010

From reactions between PtX2( deen ) (X=I, Br or Cl ; deen = N,N-diethylethane-1,2-diamine), thallous pentafluorobenzoate or 2,3,5,6-tetrafluorobenzoate, and the appropriate polyfluorobenzene in pyridine (py) or 4-methylpyridine ( mepy ), the organoamidoplatinum (II) complexes [Pt(NRCH2CH2Net2)X(L)](R = p-HC6F4 or C6F5, X = 1, Br or Cl , L = py; R = p-HC6F4, X = I, L = mepy ; R = p-MeC6F4 or p-IC6F4, X = I, L = py; R = 2,3,5-F3C6H2, X = Br, L = py) have been prepared. The X-ray crystal structure of [Pt(NC6F5CH2CH2Net2)I(py)](triclinic, space group Pī (No. 2), a 9.308(1), b 9.615(2), C 11.143(2)Ǻ, α 88.70(2),β 88.58(1), γ 89.60(2)°, R 0.0518, Rw 0.0704 for 3237 observed reflections) shows the complex to have square planar stereo-chemistry with py trans to NEt2 and NC6F5 trans to iodine. The stereochemistry of the amido nitrogen approaches triangular (sum of angles 353°) and the N-C6F5 bond has partial double-bond character. Surprisingly, the ethyl substituents have a configuration in which the methyl groups are orientated back towards platinum. Other [Pt(NRCH2CH2Net2)X(L)] complexes are considered to have similar stereochemistry on the basis of comparison of spectroscopic data, particularly 3JPt,H(py) and 3JPt,H(CH2) coupling constants.
Heterocyclic Syntheses Through Electrophilic Ring Closure Reactions of ortho-Allylaniline Systems
Authors: Raner KD , Ward AD
Published: September 2010

Amide derivatives of 2-allylanilines have been prepared by metallation of the amide derivatives of the corresponding 2-bromoanilines and subsequent reaction with an allylic halide. The electrophile -promoted cyclization of these compounds has been investigated. The free allylanilines readily undergo aminomercuration to form unstable mercury derivatives of tetrahydroquinolines but the corresponding amide derivatives do not cyclize. Instead, oxymercuration of the double bond occurs. The allylanilines react with iodine to yield 3-iodo-1,2,3,4-tetrahydroquinolines. The anion of 2,2,2-trifluoro-N-[4-hydroxymethyl-2-(3-methylbut-2-enyl)phenyl] acetamide reacts with iodine to give a 2,3-dihydroindole. These iodinated compounds can be further cyclized with base to form 7,7a-dihydro-1H-azirino[1,2-a] indoles. One of these aziridine systems was cleaved with hydrogen chloride to form a mixture of chlorinated tetrahydroquinoline and dihydroindole analogous to the iodo systems.
The Synthesis and Some Properties of the First Boron-Stabilized Alkenyl Carbanions
Authors: Pelter A , Smith K , Parry DE , Jones KD
Published: September 2010

Calculations indicate a high degree of stabilization of H2BC=CH2 and that it has an allene -type structure H2B=C=CH2. Routes to boron-stabilized alkenyl carbanions have been established for the first time, and alkylation and protonation studies are described.
A Stereospecific Synthesis of (±)-Abscisic Acid
Authors: Cornforth J , Hawes JE , Mallaby R
Published: September 2010

A convenient separation of (E)- and (Z)-3-methylpent-2-enedioic acids was devised, and it was shown that with acetyl chloride or thionyl chloride the (Z)-acid yields the cyclic anhydride while the (E)-acid forms 6-chloro-4-methylpyran-2-one. The chloropyranone by conventional chemistry gave 4-methyl-6-(2′-oxopropyl)pyran-2-one which condensed with 4-methylpent-3-en-2-one in the presence of pyrrolidine, yielding 4-methyl-6-(2′,6′,6′-trimethyl-4′-oxocyclohex-2′-enyl)pyran-2-one. Oxidation with selenium dioxide or t-butyl chromate then gave 6-(1′-hydroxy-2′,6′,6′-trimethyl-4′-oxotyclohex-2′-enyl)-4-methylpyran-2-one, which on reduction by lithium aluminium hydride and reoxidation afforded (±)-abscisic acid stereospecifically.
The Stereochemistry of Ring Closure of Some Monosubstituted Ortho-(but-3-enyl)phenyl Radicals
Authors: Beckwith ALJ , Gerba S
Published: September 2010

The rates and diastereoselectivity of cyclization of o-(but-3-eny1)phenyl radicals bearing substituents on the 1- or 2-position of the side chain have been examined. 1-Substituted radicals afford only 1,5-cyclization products, but 2-substituted radicals also give small amounts of endo products by direct 1,6-cyclization. In conformity with established guidelines, the 2-substituted radicals undergo preferential formation of trans- disubstituted products. However, 1-substituted radicals cyclize with relatively low diastereoselectivity , and the preferred stereochemistry of the product depends on the nature of the substituent . Transition structure strain energies calculated by the MNDO/MM2 method provide qualitative indices of reactivity and diastereoselectivity.
Structure and Absolute Configuration of the Ansamycin Antibiotic Awamycin
Authors: Herlt AJ , Rickards RW , Robertson GB
Published: September 2010

The structure and absolute configuration (3) of the biologically active ansamycin antibiotic awarnycin have been determined from X-ray diffraction data recorded at 129 K. Crystals are monoclinic, space group P2′2′2′, with a 25.426(3), b 30.823(2), c 13.592(1) A, and contain two molecules of the antibiotic and eleven solvent molecules (two water and nine ethanol) in each asymmetric scattering unit. The structure was solved with SHELXS and refined by full-matrix least-squares analysis to R 0.076 ( Rw 0.090) for 7308 reflections and 1174 refined parameters. Analysis of observed and calculated Bijvoet differences with the statistic Χ2 defines the absolute configuration of awamycin as 20R,21R,22R,23R,24R,25R,26R,27S,28S and the helicity as P. This is the first crystal structure analysis of an underivatized ansamycin antibiotic of the subgroup possessing an 18-membered ansa chain, and the first such analysisof an underivatized ansarnycin antibiotic in which it has been possible to assign absolute stereochemistry by the Bijvoet method. The constitution and absolute configuration of awamycin are compared with those of related ansarnycins carrying 18- and 19-membered ansa chains, and the tertiary structures of awarnycin and of several rifamycins and variants are analysed in relation to the arrangement of oxygen functions required for antibiotic activity.
Nitrones and Oxaziridines. XLII. Synthesis of Indol-3-yl-Substituted 1-Pyrroline 1-Oxides
Authors: Black DS , Debdas RB , Kumar N
Published: September 2010

The 1-pyrroline 1-oxides (13), (14), (16) and (18) with indol-3-yl substituents attached to the 2- or 4-positions have been synthesized by reductive cyclization of the related γ-nitro ketones. The corresponding 1-pyrrolines (15), (17) and (19) have also been isolated as the result of non-selective reduction. The 1-pyrroline 1-oxides cannot be converted into the related 2H-pyrroles, nor can they be oxidized by nitric acid to α- hydroxy ketones , as can simpler 2,4-diaryl-1-pyrroline 1-oxides.
E.S.R. Spectra of Free Radicals Relevant to Methacrylate Polymerization
Authors: Keah HH , Rae ID , Hawthorne DG
Published: September 2010

Carbon-based free radicals
were generated by thermal cleavage of the tetraester Me2C(COOME)-CH2-CMe( COOMe )- CMe ( COOMe )-CH2-C( COOMe )Me2 which is a model for head-to-head units in a poly(methyl methacrylate ) chain. The resulting electron spin resonance spectrum had higher resolution than the 'nine-line' spectrum previously reported; this enabled identification of the component radicals. In the present case, the spectrum was well matched by a summation of spectra of the Me2C(COOME)-CH2-CMe( COOMe ) radical and the 1-methoxycarbonyl-1-methylethyl radical Me2-C-COOMe derived from it by loss of methyl methacrylate. Both of these radicals were generated in separate experiments. Radicals were also generated from starting materials containing a CD3 group in place of the single CH3.
The Chlorination of 2-t-Butyl-4-chloro-6-methylphenol. Some Reactions of Chlorine and Nitrogen Dioxide With 6-Chlorocyclohexa-2,4-dienones Derived From 2-t-Butyl-4-chloro-6-methylphenol
Authors: Hartshorn MP , Roddick AD , Steel PJ , Wright GJ
Published: September 2010

Chlorinations of 2-t-butyl-4-chloro-6-methylphenol(10) and of the mixture of 4,6-dichlorocyclo-hexa-2,ddienones (11) and (12) give the tetrachloro ketones (13)-(15). Reaction of the dichlorocyclohexa-2,4-dienone mixture with nitrogen dioxide gives predominantly dichloro dinitro ketones (17) which rearrange on chromatography to yield the hydroxy dienone (21). X-Ray crystal structures are reported for compounds (13)-(15), (20) and (21).
Solubilization of pada in Hydrocarbon Fluorocarbon Surfactant Mixtures
Authors: Connolly TJ , Reinsborough VC , Xiang XY
Published: September 2010

Solubilities of pyridine-2-azo-p-dimethylaniline ( pada ) were determined at 25�C in four mixed fluorocarbon/hydrocarbon short-chained surfactant systems: ( i ) sodium decyl sulfate/sodium perfluoroheptanoate; (ii) sodium octanesulfonate /sodium perfluorooctanoate ; (iii) sodium octanesulfonate /sodium perfluoroheptanoate ; (iv) sodium nonanesulfonate /sodium perfluoroheptanoate. Systems ( i ), (iii) and (iv) showed micellar miscibility (one mixed micelle) and synergistic solubilization effects. System (ii) had two critical micelle concentrations pointing to two micellar forms in solution, and no synergism could be detected. From these four examples, it is deduced that single mixed micelles are formed when the critical micelle concentrations of the pure surfactants are within a factor of 3 of each other.
The Crystal and Molecular-Structure of fac,fac-Mo2(CO)6(Ph2AsCH2CH2PPh2)3 a Case of Chemically Imposed Disorder in the Crystal Structure
Authors: Abrahams BF , Colton R , Hoskins BF , Mcgregor K
Published: September 2010

Crystals of fac,fac-Mo2(CO)6(ape)3 (ape = Ph2AsCH2CH2PPh2) are monoclinic, P 21/n (No. 14), a 15.842(4), b 17.178(4), c 14.144(4) �, β 98.80(3)�. The compound is dimeric with a bridging ape group, and the stereochemical arrangement of the carbonyl groups about each metal atom is facial. The facial arrangement leads to a chemically imposed disorder among the ape ligand donor atoms; this makes it impossible to distinguish arsenic and phosphorus atoms in the crystal structure determination.
Synthesis of a Nagilactone Analog From Totarol
Authors: Bendall JG , Cambie RC , Rutledge PS , Woodgate PD
Published: September 2010

Totarol(1) has been converted into the nagilactone-A analogue (25) by oxidative decarboxylation of the acid (18). Acid (18) was formed from the benzyl ester (20) after removal of the protecting group by hydrogenolysis, thereby circumventing a difficult hydrolysis step encountered in a previous conversion of the methyl ester (19) into (25).