bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Reaction of Dihalocarbenes with Quadricyclane
Authors: Jefford Charles William , Roussilhe Jacques , Papadopoulos Mihail 
Published: December 2004

AbstractThe reactions of difluoro‐, dichloro‐ and dibromocarbene with quadricyclane (2) were examined. In all cases, conversions were low (4–15%), but three distinct reaction courses were observed: cleavage, 1,2‐addition, and 1,4‐addition. Difluorocarbene gave mainly 6‐endo‐(2,2‐difluorovinyl)‐cis‐bicyclo[3.1.0]hex‐2‐ene (8; 52–89% relative yield), together with minor amounts of exo‐3,3‐difluorotricyclo[3.2.1.02,4]oct‐6‐ene (7; 13–17%), and 4,4‐difluorotetracyclo[3.3.0.02,8.03,6]octane (5; 2–4%). Dichlorocarbene gave analogous products, but in relative yields of 35 (17), 51 (11), and 12% (16). The product 11 of 1,2‐endo addition underwent further rearrangement to its allylic derivative 12. A small amount of 1,2‐endo addition also occurred (2% of 14/15). Dibromocarbene gave predominantly products derived from rearrangement of the 1,2‐exo (61% of 20/21) and 1,2‐endo adducts (10% of 23/24). In addition, a significant amount of 4,4‐dibromotetracyclo[3.3.0.02,8.03,6]octane (25; 21%) was formed. The cleavage product, 6‐endo‐(2,2‐dibromovinyl)‐cis‐bicyclo[3.1.0]hex‐2‐ene (26) was also observed (7%). The yields and product compositions were compared to those obtained from norbornadiene (1) and found to be entirely different (Table 1), for example no cleavage occurred with difluorocarbene.
Picosecond Time Resolved Studies of Photosensitized Electron Injection in Colloidal Semiconductors
Authors: Moser Jacques , Grätzel Michael , Sharma Devendra K. , Serpone Nick 
Published: December 2004

AbstractUsing a single picosecond pulse from a frequency‐doubled Nd:YAG‐mode‐locked laser for excitation, we measured directly the rate of electron injection from the excited singlet state of eosin in the conduction band of colloidal TiO2 particles. The rate constant for interfacial electron transfer is 9.5 × 108s−1 at 25°C and pH 3.
Nucleophilic Additions to N‐Glycosylnitrones. Asymmetric Synthesis of α‐Aminophosphonic Acids
Authors: Huber Rolf , Knierzinger Andreas , Obrecht Jean‐Pierre , Vasella Andrea 
Published: December 2004

AbstractThe hypothesis which explains the diastereoselectivity of the 1,3‐dipolar cycloaddition of the N‐glycosylnitrones 1–3 leading to the 5,5‐disubstituted isoxazolidines 4–6 on the basis of a kinetic anomeric effect predicts that nucleophiles should add to N‐glycosylnitrones with a high degree of diastereoselectivity. To test this prediction, the nucleophilic addition of lithium and potassium dialkylphosphites to the crystalline (Z)‐nitrone 11, prepared from oxime 9 and (benzyloxy)acetaldehyde has been examined. The addition of lithium phosphites gave the N‐glycosyl‐N‐hydroxyaminophosphonates 12–16 (d. e. 78–92%) in high yields (Scheme 4). The addition of potassium phosphites showed a much lower diastereoselectivity. Glycoside cleavage, hydrogenolysis, and dealkylation of 12–16 gave (+)‐(S)‐phosphoserine (+)‐19 (34–45% from 9). Its absolute configuration was confirmed by an X‐ray analysis of the N‐(3,3,3‐trifluoro‐2‐methoxy‐2‐phenylpropionyl) derivative 24. Similarly, the crystalline nitrone 25 gave the N‐glycosyl‐N‐hydroxyaminophosphonate 26, which was transformed into (+)‐(S)‐phosphovaline (+)‐31 (42% from 9). The diastereoselectivity of the nucleophilic addition and the enantiomeric purity of (+)‐31 were determined by the analysis of the derivative 30 (d.e. 92%) and 32 (d.e. 93%), respectively. The addition of lithium diethyl phosphite to the nitrone 33, prepared in situ, gave the N‐glycosyl‐N‐hydroxyaminophosphonate 34, (41%; d.e. 91%), which was transformed in (+)‐(S)‐phosphoalanine (+)‐37 (21% from 9).
Heterocyclic Rearrangement of 4,5,6,7‐Tetrahydro‐6,6‐dimethyl‐benzo[c][1,2,5]oxadiazol‐4‐one (Z)‐Arylhydrazones into Corresponding 2‐Aryl‐4,5,6,7‐tetrahydro‐2H‐benzo[d][1,2,3]triazol‐4‐one Oximes
Authors: Lefkopoulou Susan , Stephanidou‐Stephanatou Julia , Tsoleridis Constantine , Alexandrou Nicholas E. 
Published: December 2004

AbstractThe thermal base‐catalysed and photochemical transformation (Boulton‐Katritzky rearrangement) of the title tetrahydrobenzo[c][1,2,5]oxadiazoles to tetrahydro‐2H‐benzo[d][1,2,3]triazoles is studied. Attempts to induce analogous rearrangement in tetrahydro‐2H‐benzo[d][1,2,3]triazol‐4‐one arylhydrazones or oximes failed. Some CNDO/2 calculation are also carried out.
Structure and Reactivity of Xanthocorrinoids. Part III. The first example of a pinacol‐type rearrangement in the corrin series
Authors: Grüning Burghard , Holze Gerhard , Gossauer Albert , Ernst Ludger 
Published: December 2004

AbstractThe transformation of the c‐acetic‐acid chain of hexamethyl Coα, Coβ‐dicyanocobyrinate into an ethyl group (→2) as well as the synthesis of the pentadecaalkyl‐cobalticorrin 6d from commercial cyanocobalamin are described. On reaction of 2 or 6d with O2 in the presence of ascorbic acid, migration of the CH3 group at C(5) to the vicinal position C(6) takes place concomitantly with the introduction of a carbonyl group at C(5).
Neue Dimethinmerocyaninfarbstoffe mit J‐Aggregation in stark verdünnter Lösung
Authors: Langhals Elke , Balli Heinz 
Published: December 2004

Novel Dimethinmerocyanine Dyes Performing J‐Aggregation in Highly Diluted SolutionA series of various novel long‐chain alkyl‐dimethinmerocyanine dyes containing sulfonate groups is obtained in high yield by modified condensation reactions of sulfoalkyl‐ or sulfophenylsubstituted methylene ketones. The dyes exhibit intense, red‐shifted absorption bands (ϵ up to 263 000) due to J‐aggregation in DMSO/H2O mixtures without addition of salt even at dye concentrations of 5 · 10−8M. The influence of dye structure and medium on the aggregation tendency is investigated. Besides it is found that exchange of the cationic counterions does not affect J‐aggregation.
The Characterization of Natural and Artificial Calcium Carbonates by Adsorption and Immersion Techniques
Authors: Morel Daniel , Stoeckli Fritz , Krähenbühl Francis , Misteli Laurent , Munyazikwiye Paulin 
Published: December 2004

AbstractNitrogen adsorption isotherms at 77K and enthalpies of immersion into water at 293K have been measured for a series of artificial and natural calcium carbonates. It appears that the external surface area and the micropore system can be fully characterized if a non‐porous sample, present in the series, is used as an internal reference. Data are given for the reference isotherm. Owing to high specific interactions, immersion into water only provides information on the total surface area of the samples.
Convenient Preparation and Spectroscopic Characterization of Methyl Hydrodisulfide and Methyl Deuterodisulfide
Authors: Grassi Guido , Tyblewski Marek , Bauder Alfred 
Published: December 2004

AbstractMethyl hydrodisulfide and methyl deuterodisulfide have been prepared in a four‐step synthesis. These compounds have been characterized spectroscopically including microwave spectra.
Synthesen von optisch aktiven Carotinoiden mit einer (R)‐4‐Hydroxy‐β‐Endgruppe
Authors: Haag Andreas , Eugster Conrad Hans 
Published: December 2004

Synthesis of Optically Active Carotenoids with (R)‐4‐Hydroxy β‐End GroupsWe describe the synthesis of optically active iso‐β‐kryptoxanthin (12; (R)‐β,β‐caroten‐4‐ol), iso‐α‐kryptoxanthins 14 ((4R,6′RS)‐β,ε‐caroten‐4‐ol) and 16 ((4R,6′R)‐β,ε‐caroten‐4‐ol), 4′‐hydroxyechinenone (18; (R)‐4′‐hydroxy‐β,β‐caroten‐4‐one), and isorubixanthin (20; (R)‐β,ω,‐caroten‐4‐ol), their 400‐MHz‐1H‐NMR spectra, CD spectra and HPLC behaviour.
Synthesis of Oligodeoxynucleotides by the Phosphite‐Triester Method Using Dimer Units and Different Phosphorous‐Protecting Groups
Authors: Bannwarth Willi 
Published: December 2004

AbstractA simple synthesis of phosphoamidite dinucleotides with two different phosphorous‐protecting groups and their use for the synthesis of 2′‐oligodeoxynucleotides on a polymer support is reported.
The Reductive Conversion of Some Cyclic and Acyclic vic‐Epoxides to Alcohols by Means of Lithium Aluminium Hydride/Aluminium Trichloride
Authors: Andrejević Vladimir , Bjelaković Mira , Mihailović Milan M. , Mihailović Mihailo Lj. 
Published: December 2004

AbstractUnsubstituted medium‐ring 1,2‐epoxycycloalkanes and certain vic‐epoxyalkanes are reduced to the corresponding alcohols very slowly when LiAlH4 alone is used as reducing agent. However, the combination of LiAlH4 and AlCl3, in a 2:1 molar ratio (with respect to 1 mol‐equiv. of epoxide) used in refluxing Et2O, greatly enhances these reductions, rendering them of interest for practical purposes.
Propellanes. Part LXXXII. Preparation and Labelling of [20.3.3]Propellane‐24,27‐dione
Authors: Ashkenazi Pnina , Kettenring Jürgen , Migdal Shmuel , Gutman Arie L. , Ginsburg David 
Published: December 2004

AbstractThe title diketone has been prepared by a synthetic sequence beginning with decane‐1,10‐dicarboxylic acid.
Reactions of Cyclopalladated Benzylidene‐aniline Schiff's Base Complexes. Selective Synthesis of 2′‐Substituted Schiff's Base Derivatives and the X‐Ray Crystal Structure of the Dimer [Pd(μ‐OAc)(5′‐OCH3C6H3CHNC6H4‐4‐CH3)]2
Authors: Albinati Alberto , Pregosin Paul S. , Rüedi Regula 
Published: December 2004

AbstractThe 2′‐cyclopalladated imine complex , reacts with CO in MeOH to afford the 2′‐substituted aryl imine 2′‐CO2CH3‐5′‐OCH3C6H3CHNTol (Tol = C6H4‐4‐CH3). The product of this reaction can be altered by changing the bridging ligand from AcO to Cl, in which case only the 5‐membered ring heterocyclic compound is obtained. [Pd(μ‐OAc)(1a)]2 with 2 equiv. of Ph3P and CO (1 atm) gives the heterocyclic which arises from two CO insertion reactions, whereas [PdX(1a)]2 (X = AcO, Cl) with 4 equiv. of CNBut and 4 equiv. of Ph2PCH2CH2PPh2 affords the heterocyclic ketenimine [PdCl(1a)]2 reacts with CH2CHCO2CH2CH3 to afford 2′(CHCHCO2CH2CH3)‐5′‐OCH3C6H3CHO, and [Pd(μ‐OAc)(1a)]2 with I2 to give 2′‐I‐5′‐OCH3C6H3CHO. Excess CH3O2CCCCO2CH3 reacts with various substituted cyclopalladated Schiff's bases in MeOH to afford which we formulate as possessing two PdC bonds, and one coordinated ester O atom. The X‐ray crystal structure of [Pd(μ‐OAc)(1a)]2 has been determined; relevant bond lengths [Å] and bond angles [°] are: PdO(1), 2.139(6), PdO(2), 2.026(6), PdN, 2.039(6), PdC(2′), 1.951(8), PdPd, 3.113(1), NPdC(2′), 80.9(3), NPdO(1), 97.5(2), C(2′)PdO(2), 91.7(3), O(1)PdO(2), 89.2(2).
Synthesen überbrückter Bischinonmethide mit doppelter Acylketenaminal‐Struktur
Authors: Neidlein Richard , Hartz Georg 
Published: December 2004

Syntheses of Bridged Bisquinonemethides with Double Acylketeneaminal StructureStarting with 1, the synthesis of bis(tert‐butyl)ester 2 is described. Some reactions including methylation of 2 to give 3 and 4, (4 → 5) and deprotonation of 5 to 6 are reported. Possible structures of deprotonation products are discussed, based on NMR results.
Note on Attempts to Prepare Ring‐B Homomorphinan‐6‐ones by Grewe Cyclization from Octahydro‐1‐phenethylisoquinolines
Authors: Dumont Raymond , Pfander Hanspeter , Brossi Arnold 
Published: December 2004

AbstractGrewe cyclization of the N‐formyl‐protected octahydroisoquinolin‐6‐one 1 prepared by conventional chemistry did not afford the expected homomorphinanone. The exclusive reaction product obtained in good yield was the α,β‐unsaturated N‐formyloctahydroisoquinolin‐6‐one 2, further converted by acid hydrolysis into the crystalline octahydroisoquinolin‐6‐one 8.
Ringerweiterung bei der Reaktion eines 1,3‐Cyclohexandions mit Diphenylcyclopropenon
Authors: Bilinski Vanda , Dreiding André S. 
Published: December 2004

Ring Expansion during the Reaction of a 1,3‐Cyclohexanedione with DiphenylcyclopropenoneThe reaction of 5,5‐dimethyl‐1,3‐cyclohexanedione (1) in form of its Na‐salt with diphenylcyclopropenone (2) in DMF yielded the bicyclic triketone 3 (58 %), the structure of which was deduced as an enolizeable bicyclo[5.2.0]nonane‐β‐diketone from spectral data and from the following reactions: hydrolysis or methanolysis of 3 cleaved the β‐dicarbonyl moiety, thereby opening the 4‐membered ring to yield the keto acid 9 or its methyl ester 10. Methylation of 3 afforded the two enol ethers 4 and 5. The ether 5 readily underwent a thermal electrocyclic ring opening to the monocyclic enol ether 8, whereas the ether 4 was thermally stable. The same electrocylic ring opening (in boiling benzene) converted 3 (probably via 3b) to the monocyclic triketone 7, which was also the hydrolysis product of the ring‐opened enol ether 8. By heating 3 in DMF/H2O, a partial (56 %) conversion to the lactone 6 took place. The tricyclic intermediate 11 was found useful to rationalize the ring expansion during the formation of 3 from 1 and 2 as well as the corresponding ring contraction during the conversion of 3 into 6.
Two New Syntheses of the Pyranojuglone Pigment α‐Caryopterone
Authors: Matsumoto Takeshi , Ichihara Akitami , Yanagiya Mitsutoshi , Yuzawa Tamio , Sannai Akiyoshi , Oikawa Hideaki , Sakamura Sadao , Eugster Conrad Hans 
Published: December 2004

AbstractBy a simple process, 3‐methoxyjuglone (= 8‐hydroxy‐2‐methoxy‐1,4‐naphthoquinone; 9) has been synthesized from 1,2,4‐trimethoxybenzene (5) and converted, after prenylation, to α‐caryopterone (1; Scheme 1), a pyranojuglone pigment from Caryopteris clandonensis. On the other hand, juglone (= 5‐hydroxy‐1,4‐naphthoquinone; 12) was regioselectively prenylated at C(2) via its 1‐methoxy‐cyclohexa‐1,3‐diene adduct 15 (Scheme 2). The 2‐prenyljuglone (4) thus formed led to 1 after oxidation and other reactions.
Template Synthesis, Crystal Structure, and Spectroscopic Characterization of [N,N′‐Bis(2‐pyridylmethylene)‐1,3‐diamino‐2‐methyl‐2‐nitropropane] copper(II) Perchlorate
Authors: Comba Peter , Hambley Trevor W. , Lawrance Geoffrey A. 
Published: December 2004

AbstractIn a facile carbon‐acid condensation reaction of bis(2‐aminomethylpyridine)copper(II) with nitroethane and formaldehyde in basic MeOH the N,N′‐bis(2‐pyridylmethylene)‐1,3‐(diamino‐2‐methyl‐2‐nitropropane)copper(II) cation is produced in essentially quantitative yield. The perchlorate salt crystallizes in space group P21en, a = 9.083(2), b = 15.198(3), c = 16.025(3). Cu(II) is essentially four‐coordinate, though there are weak axial interactions to the perchlorate O‐atoms. There is a large tetrahedral distortion from the least‐squares plane through the Cu and four N donors; with the Cu(II) in the plane, N‐atoms are up to 0.25 Å above or below. Solution spectroscopy confirms that the solution structure of the cation is qualitatively the same as in the solid. The complex and its precursor have been investigated by room‐temperature magnetic‐moment measurement, voltammetry, and by IR, electronic, and electron spin resonance spectroscopy.
Inhibition of Emulsin by D‐Gluconhydroximo‐1,5‐lactone and Related Compounds
Authors: Beer Dieter , Vasella Andrea 
Published: December 2004

AbstractAt pH 4.5 (citrate buffer), D‐gluconhydroximo‐lactone (2), the N‐methylurethane 3 and the N‐phenylurethane 4 inhibit competitively the hydrolysis of p‐nitrophenyl β‐D‐glucopyranoside by emulsin. The IC50 values of 2, 3, and 4 were 1.6 × 10−4, 1.0 × 10−4, and 5.8 × 10−6 M, respectively. The Ki values of 2 and 4 were 9.8 × 10−5 and 2.3 × 10−6 M, respectively, while D‐glucono‐1,5‐lactone (1) showed IC50 = 1.1 × 10−4 M and Ki = 3.7 × 10−5 M.
Circular Dichroism of Tricarbonyl(diene)iron Complexes. The Octant Rule Applied to Ketones Perturbed by Remote Fe(CO)3 Groups. Crystal Structure of (±)‐Tricarbonyl[(1RS,4RS,5RS,6SR)‐C5,6,C‐η‐(5,6,7,8‐tetramethylidene‐2‐bicyclo[2.2.2]octanone)]iron
Authors: Gabioud Raphy , Vogel Pierre , Pinkerton Alan A. , Schwarzenbach Dieter 
Published: December 2004

AbstractThe preparation and the CD spectra of optically pure (+)‐trans‐μ‐[(1R,4S,5S,6R,7R,8S)‐C,5,6,C ‐η : C,7,8,C‐η‐(5,6,7,8‐tetramethylidene‐2‐bicyclo [2.2.2]octanone)]bis(tricarbonyliron) ((+)‐7) and (+)‐tricarbonyl[(1S,4S,5S,6R)‐C‐5,6,C‐η‐(5,6,7,8,‐tetramethylidene‐2‐bicyclo[2.2.2]octanone)]iron ((+)‐8), and of its 3‐deuterated derivatives (+)‐trans‐μ‐[(1R,3R,4S,5S,6R,7R,8S)‐C,5,6,C‐η : C,7,8,C‐η‐5,6,7,8‐tetramethylidene(3‐D)‐2‐bicyclo[2.2.2]‐(octanone)]bis(tricarbonyliron) ((+)‐11) and (+)‐tricarbonyl[(1S,3R,4S,5S,6R)‐C‐5,6,C‐ η‐(5,6,7,8‐tetramethylidene(3‐D)‐2‐bicyclo[2.2.2]octanone)]iron ((+)‐12) are reported. The chirality in (+)‐7 and (+)‐8 is due to the Fe(CO)3 moieties uniquely. The signs of the Cotton effects observed for (+)‐7 and (+)‐8 obey the octant rule (ketone n→π*CO transition). Optically pure (−)‐3R‐5,6,7,8‐tetramethylidene(3‐D)‐2‐bicyclo[2.2.2]octanone ((−)‐10) was prepared. Its CD spectrum showed an ‘anti‐octant’ behaviour for the ketone n→π*CO transition of the deuterium substituent. The CD spectra of the alcoholic derivatives (−)‐trans‐μ‐[(1R,2R,4S, 5S,6R,7R,8S)‐C,5,6,C‐η : C,7,8,C‐ η‐(5,6,7,8‐tetramethylidene‐2‐bicyclo[2.2.2]octanol)]bis(tricarbonyliron) ((−)‐2) and (−)‐tricarbonyl‐ [(1S,2R,4S,5S,6R)‐ C,5,6,C‐ η‐(5,6,7,8‐tetramethylidene‐2‐bicyclo[2.2.2]octanol)]iron ((−)‐3) and of the 3‐denterated derivatives (−)‐5 and (−)‐6 are also reported. The CD spectra of the complexes (−)‐2, (−)‐3, (+)‐7, and (+)‐8 were solvent and temperature dependent. The ‘endo’‐configuration of the Fe(CO)3 moiety in (±)‐8 was established by single‐crystal X‐ray diffraction.
Preparation of Optically Active Secondary Amines by Thermal Decomposition of (Methylbenzyl)urea Analogs: Absolute Configuration of (+)‐ and (−)‐Mecamylamine. Preliminary Communication
Authors: Schönenberger Bernhard , Brossi Arnold , George Clifford , Flippen‐Anderson Judith L. 
Published: December 2004

AbstractThermolysis of the (α‐methylbenzyl)urea diastereoisomers 4 and 5 of (±)‐mecamylamine ((±)‐1) and 6 and 7 of (±)‐1‐noreseroline O‐methyl ether ((±)‐3) in refluxing alcohol afforded optically pure amines in high yield, besides optically pure carbamates of (α‐methylbenzyl)amine which can be recycled. The absolute configuration of (−)‐mecamylamine hydrochloride ((−)‐1 · HCl) was determined by X‐ray diffraction analysis.
Synthese von 4,4‐disubstituierten 1,3‐Thiazol‐5(4H)‐thionen
Authors: Jenny Christjohanes , Heimgartner Heinz 
Published: December 2004

Synthesis of 4,4‐Disubstituted 1,3‐Thiazol‐5(4H)‐thionesAn easy synthesis for the 1,3‐thiazol‐5(4H)‐thiones 5, a class of heterocycles which have hitherto only been available with difficulty, is described. Reaction of 3‐amino‐2H‐azirines 25 with thiocarboxylic acids at 0° yields monothiodiamides of type 20 (Scheme 6) which, on treatment with Lawesson reagent at 100°, undergo thiation and cyclization to give 5 in good yield.
Ditopic Ligands. The Synthesis of a Series of Phosphine‐Functionalised Macrocycles
Authors: Carroy Annick , Richard Langick C. , Lehn Jean‐Marie , Matthes Karen E. , Parker David 
Published: December 2004

AbstractThe synthesis of a series of phosphine‐functionalised macrocycles, 1–6, is described. The combination of N‐and O‐sites with P‐ and S‐sites provides ligands which may bind transition or non‐transition metal ions; as a consequence, they give access to dinuclear complexes containing both a Lewis acid and a redox metallic site. Compounds 1,2 and 6 are heterodinucleating ligands capable of binding two dissimilar metals in proximity. Macrocycles 3–5 are homotopic ligands which may form homodinuclear complexes of transition metals.
The mass spectra of organic compounds. 8th Communication. 1‐Buten‐3‐yn‐2‐ol. A new kinetically unstable C4H4O isomer
Authors: Tureček František , Havlas ZdenêK , Maquin Francis , Gäumann Tino 
Published: December 2004

AbstractThe unstable neutral enol, 1‐buten‐3‐yn‐2‐ol, and its deuterium‐labelled analogues were generated in the gas phase by high‐vacuum flash pyrolysis of the corresponding 2‐exo‐ethynylnorborn‐5‐en‐2‐ols, or alternatively from 1‐ethynylcyclobutanol. The ionization energy of the enol was measured as 8.92 ± 0.03 eV. The cation radical (HCC(OH)CH2)+· was prepared by electron‐impact ionization of the neutral enol, or by dissociative ionization of 1‐hexyn‐3‐ol and 1‐ethynylcyclobutanol, and its heat of formation was determined as 944 kJ·mol−1. The heat of formation of the neutral enol was assessed as 83 ± 7 kJ·mol−1 in good agreement with MNDO calculations. Cation radicals HCCC(OH)CH2+· undergo four main unimolecular fragmentations due to losses of the OH H‐atom, a CH3 group incorporating the C(1) methylene and the OH H‐atom, CO, and H2O. The structure of the neutral enol and the mechanisms of the ionic decompositions are discussed.
Pteridine. Teil LXXIX. Synthese, Reaktionen und Photochemie heterocyclischer N,‐Alkylthioamide
Authors: Heckel Armin , Pfleiderer Wolfgang 
Published: December 2004

Synthesis, Reactions, and Photochemistry of Heterocyclic N‐AlkylthioamidesVarious heterocyclic N‐alkylthioamides of the pteridine (2, 7) and pyridine series (13) have been synthesized and investigated regarding their photooxidation. The compounds are very photolabil under aerobic conditions and are converted into the corresponding amides (1, 6 and 12, resp.) on irradiation.
Ion‐Molecule reaction in the gas phase part VI Regioselective SN2 reaction from terpenoid diastereoisomeric diols using CI/NH
Authors: Tabet Jean‐Claude , Prevost Chantal , Bouillot Anne , Bastard Josette , Manh Due Do Khae , Tondeur Yves 
Published: December 2004

AbstractA stereospecific and regioselective SN2 mechanism (Walden inversion) is observed during studies involving modified terpenoid epimeric diols in a high‐pressure ion source using ammonia as a reagent gas.
Poly{[μ‐(2,5‐dicarboxypyrazine‐ 3,6‐dicarboxylato)‐trans‐diaquairon(II) dihydrate]}, a Member of a New Class of Quasi‐Linear Chain Compounds. Preparation, Structure, and Magnetic Susceptibility
Authors: Marioni Pierre‐Alain , Steeckli‐Evans Helen , Marty Werner , Güdel Hans‐Ulrich , Williams Alan F. 
Published: December 2004

AbstractThe title compound 1, {[Fe(H2pztc)(H2O)2] · 2 H2O}∞, has been prepared from pyrazinetetracarboxylic acid (H4pztc) and Fe(II) salt in H2O. It crystallizes in the monoclinic space group P21/a with cell parameters a = 13.56(1) Å, b = 7.17(1) Å, c = 6.48(1) Å, β = 101.0(2)°, V = 618.4 Å3. The molecules form infinite parallel chains with bis(bidentate) coordination (through N and O) of the bridging pyrazine ligands. Two trans‐COOH groups of the ligand remain uncoordinated, and two trans‐H2O ligands complete a pseudo‐octahedral Fe(II) coordination which is distorted by the steric effect of the free COOH groups. The parallel polynuclear chains are linked through an extended network of H‐bonds involving the COO functions of the bridging ligand and the coordinated and lattice H2O molecules. Mössbauer and magnetic‐susceptibility data suggest normal paramagnetic behaviour of high‐spin Fe2+. An observed drop below 15 K in effective magnetic moment for 1 was attributed to temperature‐dependent population changes of the levels of the ground state 5Γ, and not to antiferromagnetic coupling (J < 1 cm−1). This result establishes that the obvious potential magnetic exchange pathway through the pyrazine bridges is inefficient, and this may be attributed, in part, to the high planarity of Fe(H2pztc) moieties.
1H‐and 13C‐NMR Investigation of Pentafulvenes
Authors: Bönzli Peter , Otter Albin , Neuenschwander Markus , Huber Hanspeter , Kellerhals Hans Peter 
Published: December 2004

Abstract1H‐ and 13C‐NMR spectra of a series of 6‐(p‐X‐phenyl)pentafulvenes 1–9 as well as of 6‐R‐substituted and 6,6‐R1,R2‐disubstituted pentafulvenes 10–23 have been analysed. It turns out that the π‐system of pentafulvenes is an attractive probe for the investigation of electronic substituent effects. Changes of vicinal H,H‐coupling constants with increasing electron‐donating capacity of the substituents X and R are interpreted in terms of an increasing π delocalisation in the 5‐membered ring, and linear correlations of Hammett Substituent constants σ or MNDO‐calculated C–C bond lengths and 3J values are observed. On the other hand, a systematic high‐field shift of 13C chemical shifts of the ring C‐atoms is induced by electron‐releasing substituents R and X, which decreases in the series C(5) > C(2)/C(3) > C(1)/C(4), and which mainly reflects changes in π‐charge density.