bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zinkchloridkatalysierte, thermische Umlagerungen von N‐Allyl in C‐Allyl‐aniline; ladungsinduzierte, aromatische Amino‐Claisen‐Umlagerungen
Authors: Schmid M. , Hansen Hans‐Jürgen , Schmid Hans 
Published: December 2004

AbstractN‐Allyl‐2‐methylaniline (12) forms on heating at 140° in xylene in the presence of zinc chloride 2‐allyl‐6‐methylanline (19) as major compound and 4‐allyl‐2‐methylaniline (20) as well as 2,7‐dimethyl‐indoline (21) as minor products. Compound 21 is also formed when 19 is heated in the presence of zinc chloride (scheme 2). That 19 arises from a charge‐induced [3s, 3s] sigmatropic rearrangement of 12 – and 20 from two consecutive [3s, 3s]‐sigmatropic transformations – follows from the reaction of N‐crotyl‐2‐methylaniline (13) in the presence of zinc chloride at 140°. 2‐(1′‐Methylallyl)‐6‐methylaniline (22) and 4‐crotyl‐2‐methylaniline (23) are formed exclusively. Small amounts of 2,3,7‐trimethyl‐indoline (24) and 2‐(cis‐ and trans‐1′‐methyl‐propenyl)‐6‐methylaniline (cis‐ and trans‐25) are observed as by‐products. Compound 24 arises from 22 in the presence of zinc chloride (scheme 3). Similar results are obtained when N‐allyl and N‐(2′‐methylallyl)‐N‐methyl‐aniline (14 and 15, respectively) are heated in the presence of zinc chloride. Whereas 14 gives nearly exclusively 2‐allyl‐N‐methyl‐aniline (28) and only small amounts of the corresponding 1, 2‐dimethyl‐indoline (29) and of 2‐(cis‐ and trans‐propenyl)‐N‐methyl‐aniline (cis‐ and trans‐27), 15 forms comparable amounts of 2‐(2′‐methylallyl)‐N‐methyl‐aniline (30), 1,2,2‐trimethyl‐indoline (31), and 2‐isobutenyl‐N‐methyl‐aniline (32) (scheme 4). Compound 30, and also 32, are transformed into 31 on heating in the presence of zinc chloride.Charge‐induced aromatic amino‐Claisen rearrangements are also observed when N‐allylated anilinium tetraphenylborates are heated at 100–105° in hexamethyl phosphoric acid triamide. Thus, N‐allyl‐ and N‐crotyl‐N, N‐dimethyl‐anilinium tetraphenylborate (16 and 17, respectively) yield 2‐allyl‐ and 2‐(1′‐methylallyl)‐N,N‐dimethyl‐aniline (33 and 34, respectively) besides small amounts of N, N‐dimethyl‐aniline. N‐Cinnamyl‐N, N‐dimethyl‐anilinium tetraphenylborate (18) gives, besides appreciable amounts of N,N‐dimethyl‐aniline, a mixture of 2‐(1′‐phenylallyl)‐,2‐cinnamyl‐, and 4‐cinnamyl‐N, N‐dimethyl‐aniline (35, 36, and 37, respectively) in which the first two compounds predominate.
Photochemische Reaktionen. 71. Mitteilung. Die Photoisomerisierung eines spirocyclischen α, β‐Epoxyketons
Authors: Wüthrich H. J. , Siewinski A. , Schaffner H. , Jeger Oskar 
Published: December 2004

AbstractOn direct UV. irradiation and on triplet sensitization with acetophenone the spirocyclic epoxyketone (R)‐(−)‐9 undergoes racemization (Φ313/334 0.014, ΦSens 0.0060) and rearrangement to the enantiomeric spiro‐β‐diketones (R)‐(+)‐14 (Φ313/334 0.068, ΦSens 0.0037) and (S)‐(−)‐14 (Φ313/334 0.024, ΦSens 0.0023). The quantum yield data show that triplet reaction due to intersystem crossing is unimportant on direct irradiation, and they exclude that one common diradical intermediate of type d (Scheme 8) for the three reaction paths is involved in both the singlet and the triplet reaction. The postulate of photolytic CαO epoxide cleavage to intermediates of type d for the rearrangement requires that the rate of rearrangement is greater than the rate of rotation around the CαCβ; bond in a given d, and that the rate difference is greater in singlet‐generated d than in the triplet analogue. Reclosure of diradicals d and/or photolytic CαCβ cleavage to diradical e and reclosure can account for the racemization of 9.The optically active spiro‐β‐diketone 14 was found to racemize also on direct irradiation and on triplet sensitization. Furthermore, both 14 and the isomeric β‐diketone 20, which was obtained by UV. irradiation of the homocyclic epoxyketone 19, photochemically isomerize to the enol lactones 23 and 21, respectively.
A Chemical Study of Burley Tobacco Flavour (Nicotiana tabacum L.). III. Structure Determination and Synthesis of 5‐(4‐Methyl‐2‐furyl)‐6‐methylheptan‐2‐one (“Solanofuran”) and of 3,4,7‐Trimethyl‐1,6‐ dioxa‐spiro[4.5]dec‐3‐en‐2‐one (“Spiroxabovolide”), Two New Flavour Components of Burley Tobacco
Authors: Demole E. , Demole C. , Berthet D. 
Published: December 2004

AbstractTwo novel constituents of Burley tobacco condensate were shown to be 5‐(4‐methyl‐2‐furyl)‐6‐methylheptan‐2‐one (solanofuran, 4) and 3,4,7‐trimethyl‐1,6‐dioxa‐spiro[4.5]‐dec‐3‐en‐2‐one (spiroxabovolide, 6). These structures were deduced from spectral data and confirmed by synthesis.Solanofuran (4) was prepared via the dye‐sensitized photo‐oxygenation of solanone (1). This type of reaction involving the uncommon ‘diene‐addition’ of 1O2 to a conjugated acyclic diene system was thus applied for the first time to the synthesis of a terpenoid furan, a route that might have some biogenetic significance.Both solanofuran (4) and spiroxabovolide (6) display interesting organoleptic properties. Identification of these compounds increases to 210 the total number of Burley tobacco flavour constituents so far characterized in this laboratory.
Near Cancellation of Through Space and Through Bond Interaction in bicyclo[3.2.2]nona‐6,8‐diene
Authors: Goldstein M. J. , Natowsky S. , Heilbronner Edgar , Hornung V. 
Published: December 2004

AbstractThe photoelectron spectra of bicyclo[3.2.2]nonane and its five dehydrogenated analogues are reported. Analysis of the π‐bands reveals that the unsymmetrical diene 5 retains the ‘natural order’ of the π‐orbitals present in the lower homologues, i. e. the in‐phase below the out‐of‐phase combination of the basis π‐orbitals πa and πc. The isomeric diene 4 is the first member of the symmetrical homologous series (I), which inverts this order, so that a1(π) (in phase!) lies above b2(π) (out‐of‐phase!).
13C‐ and 1H‐NMR. Spectra of ortho‐benzoquinones. On the assignment problem in 13C spectra
Authors: Hollenstein R. , Von Philipsborn Wolfgang 
Published: December 2004

Abstract13C‐ and 1H‐NMR. spectra of ortho‐benzoquinone 1 and its methyl derivatives have been analysed. By means of heteronuclear double resonance experiments it is shown that assignments given in the literature for the olefinic carbon resonances of 1 and of a series of substituted ortho‐benzoquinones have to be inverted. 13C‐carbonyl frequencies of various six‐membered cyclic ketones are presented.
N, N′‐Alkylidenpeptide: Peptidsynthese‐Nebenprodukte bei Einwirkung von Carbonylverbindungen
Authors: Cardinaux F. , Brenner M. 
Published: December 2004

AbstractByproducts of peptide synthesis, formed in the course of accidental attack by Pd‐activated oxygen on ethanol and triethylamine in reaction media, have been identified as products of condensation between peptides and acetaldehyde, and demonstrated to represent N,N′‐alkylidenepeptides, i.e. derivatives of 4‐imidazolidinones. The same products are obtained by direct action of acetaldehyde on the respective peptides, and analogs resulted in some cases when acetaldehyde was replaced by formaldehyde or acetone. The condensation is reversible, imidazolidinone stability depending on structural features of both the involved peptide and carbonyl compound. There are evidently implications of these findings with respect to the chemistry and biochemistry of peptides and proteins.
Methode zur Konstitutionsaufklärung von Celluloseformalen von niedrigem Substitutionsgrad. 29. Mitteilung über textilchemische Untersuchungen
Authors: Heinisch K. A. , Katayama A. , Rouette H. K. , Zollinger H. 
Published: December 2004

AbstractA method is described which allows the determination of the hydroxyl group(s) in glucose units of cellulose which react with formaldehyde at low degrees of substitution (0.2 to 1.5% CH2O on cellulose). It consists of permethylation of the cellulose by a sequence of two methylations with dimethylsulfate and NaOH (without solvent) followed by 2 exchange methylations with methyl iodide and sodium n‐butoxide and further steps described earlier [2]. The results demonstrate that the use of the new permethylation method leads to a loss of material of less than 5%.
Zur Konfiguration der 2,4,6,8‐Tetrabrom‐cyclooctan‐1,5‐dione Reduktion des β‐Isomers durch Natrium‐borhydrid
Authors: Heller Jürg E. , Dreiding André S. 
Published: December 2004

AbstractOf the two previously described 2,4,6,8‐tetrabromo‐cyclooctane‐1,5‐diones, the higher melting β‐isomer, mp. 226°, was treated with sodium borohydride to give: (1) by a double reduction and an intramolecular SN2‐reaction two epimeric alcohols, namely the 2‐exo‐hydroxy‐ (6) and 2‐endo‐hydroxy‐ (7) isomers of 3‐exo,5‐exo,7‐endo‐tribromo‐9‐oxa‐bicyclo[4.2.1]nonane, and (2) by a single step reduction a hemiketal, 1‐hydroxy‐2‐exo,4‐exo,6‐endo,8‐endo‐tetrabromo‐9‐oxa‐bicyclo[3.3.1]nonane (8).The structures of these three hydroxy‐compounds (6, 7 and 8) were derived from their properties, especially from complete analyses of their NMR.‐spectra, which led to deductions of all configurations and conformations. Of special interest is the preferred existence of the 9‐oxa‐bicyclo[3.3.1]norane derivative 8 in a chair‐chair conformation.The derivation of the configurations of the three hydroxy‐compounds 6, 7 and 8 is tantamount to establishing the 2,4‐cis, 4,6‐trans, 6,8‐cis‐configuration (5) of the β‐isomer of 2,4,6,8‐tetrabromocyclooctane‐1,5‐dione, mp. 226°.
Neuartige Cycloadditionsreaktionen von 2‐ und 4‐Vinylpyridin mit N‐Alkyl‐maleinimiden
Authors: Wagner‐Jauregg Th. , Ahmed Q. , Pretsch E. 
Published: December 2004

Abstract4‐Vinylpyridine (1a) combines with 3 moles of dienophilic N‐alkyl‐maleinimides (2) in the presence of polymerization inhibitors. The first step of the reaction probably consists of 1:1‐addition with participation of an aromatic double bond, comparable to the analogous behavior of styrene and its derivatives under similar conditions. The unstable intermediates 3, like other Schiff bases (imines), add 2 further moles of the N‐alkyl‐maleinimides forming the spiro compounds 4. These are split in an acidic medium into the N‐alkyl‐5,6,7,8‐tetrahydroisoquinoline‐7,8‐dicarboximides (5), and N,N′‐dialkyl‐2‐butene‐1,2,3,4‐tetracarboxylic 1,2,:3,4‐diimides (6). LiAlH4 reduction of these two types of compounds leads to N‐alkyl‐1 H‐(3,4‐d)‐pyrrolo‐2,3,3a,4,5,9b‐hexahydroisoquinolines (7) and to N,N′dialkyl‐3,3′‐bipyrrolidyls (8A) and their dehydro‐products 8B, respectively.From the reaction of 2‐vinylpyridine (1b) with N‐alkyl‐maleinimides (2) the 1:2‐addition products 9 can be isolated in the presence of polymerization inhibitors, which are derivatives of N‐alkyl‐5,6,7,8‐tetrahydroquinoline‐5,6‐dicarboximides (9). This again corresponds to the reaction type of cycloadditions with styrene. Furthermore 1:3 adducts are formed which according to 1H‐ and 13C‐NMR.‐data most likely have the structure 10, representing a new type of cycloaddition involving the pyridine nitrogen.
Hydride Abstraction from Benzocyclopropene. Preliminary communication
Authors: Müller Paul 
Published: December 2004

AbstractThe reaction between benzocyclopropene (1) and triphenylmethyl fluoroborate in acetonitrile shows an isotope effect of 6.7 and the isolation of the resulting triphenylmethane and benzaldehyde has been effected. A mechanism for the formation of the latter is proposed, involving an intermediate benzocyclopropenium ion (2).
Chemically Induced Dynamic Nuclear Polarization XI. Intermediary vinyl alcohol during photochemical reactions of acetaldehyde and of acetoin
Authors: Blank B. , Fischer H. 
Published: December 2004

AbstractVinylalcohol, formed by disproportionation of α‐hydroxyethyl radicals, is detected by NMR. spectroscopy during photoreactions of acetaldehyde and acetoin in solution and slowly tautomerizes to acetaldehyde.
Eine kinetische Studie über Ligandenverdrängungsreaktionen von π‐ Allyl‐π‐cyclopentadienyl‐Metallkomplexen
Authors: Harder Viktor , Werner Helmut 
Published: December 2004

AbstractThe kinetics of the reactions of the complexes C3H5MC5H5 (M  Ni, Pd) with tertiary phosphites P(OR)3 to give M[P(OR)3]4 have been investigated. For M  Ni and R  C2H5, there results a third‐order rate law whereas for M  Pd and R  C6H5 a second‐order rate law is observed. Possible mechanistic implications of the kinetic data will be discussed.
Flash Photolysis Studies of Reversible Photoprocesses V. Photochromism and triplet states in the dianthrone system
Authors: Gschwind Kurt H. , Wild Urs P. 
Published: December 2004

AbstractThe kinetics of the formation of the photochromic forms B and C of tetramethyl‐dianthrone has been studied in triacetin and methylcyclohexane/2‐methylpentane at several temperatures. A flash spectroscopy method was developed, which allows the recording of the transient behaviour of the sample as function of both – wavelength and time – using a single photoflash for excitation. The results show that the photochromic forms B and C are directly populated from the excited singlet state. In addition a new triplet‐triplet absorption band in the near infrared region was detected.
Fulvene, VII. Analyse der 13C‐ und 1H‐NMR.‐Spektren
Authors: Hollenstein Roger , von Philipsborn Wolfgang , Vögeli Rudolf , Neuenschwander Markus 
Published: December 2004

AbstractCarbon‐13 and proton NMR. spectra of pentafulvene and of a series of 6‐substituted fulvenes have been analysed and assigned by homo‐ and heteronuclear double resonance and with the aid of iterative computation. 13C and 1H chemical shifts are interpreted in terms of substituent effects and compared with π‐electron charges calculated for the unsubstituted fulvene. From 13C shifts a 10 percent contribution of dipolar structures to the electronic configuration of fulvene may be estimated. All long‐range proton‐proton coupling constants including relative signs and some proton‐carbon couplings in the fulvene spin system have been determined and assigned.
Indices de rétention de cycloalcanes, cycloalcènes, bicycloalkyles, cycloalkyl‐cycloalcényles et bicycloalcényles en chromatographie en phase gazeuse
Authors: Besson Richard , Gäumann Tino 
Published: December 2004

AbstractThe retention indices for cycloalkanes, cycloalkenes and bicyclic compounds have been measured as a function of temperature for different liquids phases. The diastereomeric bicycloalkenyl‐2 were separated. Some rules concerning the indices are given.
The Gas‐Chromatographic Retention Indices of Deuterated Compounds
Authors: Gäumann Tino , Bonzo Reipso 
Published: December 2004

AbstractDie Änderung des Retentionsindex mit dem Deuterierungsgrad einiger Verbindungen wurden als Funktion der Temperatur und der stationären Phase untersucht. Er zeigt grosse Regelmässigkeiten in der Abhängigkeit von der Anzahl der Deuteriumatome in der Molekel und von der stationären Phase. Die Resultate gestatten eine Abschätzung der relativen Flüchtigkeit α einer deuterierten Verbindung und der Änderung der thermodynamischen Zustandsfunktionen bei der Deuterierung.
Synthesis of ‘Pear Ester’. A novel synthesis of 2,4‐diolefinic aldehydes and esters
Authors: Ohloff Günther , Pawlak Manfred 
Published: December 2004

AbstractVinylogous epoxyaldehydes undergo stereospecific Wittig condensations in high yields. The resulting diolefinic epoxides are cleaved at the C(1)–C(2) single bond, when treated with periodic acid, to give the corresponding aldehydes. Direct transformation into the corresponding ethyl‐ester leads to an efficient synthesis of the ‘pear ester’.
Dérivés C‐Glycosyliques XIV. Synthèse de Glycosyl‐5‐Δ2‐Isoxazolines
Authors: Tronchet Jean M. J. , Jaccard‐Thorndahl Sonia , Faivre Liliane , Massard Robert 
Published: December 2004

AbstractTreatment of terminal‐unsaturated sugars with stable aromatic nitrile oxides led to the expected Δ2‐isoxazolines, obtained as a mixture of two diastereoisomers epimeric at the new asymmetric carbon. One isomer (and in some cases both) has been isolated in a pure state. These compounds are potentially useful in the drug‐design of therapeutically active molecules.
Imidazole als Induktoren der Cyclo‐Oligomerisation von N‐Alkyl‐maleinimiden und der cis‐trans, Umlagerung von Maleinsäure‐dimethylester
Authors: Wagner‐Jauregg Th. , Ahmed Q. , Pretsch E. 
Published: December 2004

AbstractN‐Methylimidazole (N–M), in boiling acetonitrile, catalyzes the oligomerization of N‐alkyl maleimides (2) to tri‐, tetra‐, penta‐ and hexamers. In the presence of small amounts of hydroquinone the trimers of 2 are formed, which have the structure of N,N′,N″‐trialkyl‐cyclohexane‐1,2,3,4,5,6‐hexacarboxy‐1,2:3,4:5,6‐tri‐midies (6). A possible mechanism of this catalytic cyclo‐oligometization is discussed. Dependant from the chemical nature of the N‐alkyl substituent of the maleimides, imidazole or benzimidazole and some of its C‐substituted products also can function as oligomerization catalysts. However in this case the normal 1:1 addition is the main reaction, as observed also with pyrazoles plus 2. Maleic dimethylester was isomerized to fumaric dimethylester in the presence of N‐methylimidazol. These observations reveal additional catalytic functions to the well known hydrolysis catalyzing properties of imidazoles.
The Preparation of Merrifield‐Resins Through Total Esterification With Cesium Salts
Authors: Gisin B. F. 
Published: December 2004

AbstractThe reaction of chloromethylated polystyrene‐co‐1%‐divinylbenzene resin with the cesium salts of N‐protected amino acids proceeds fast and without side reactions to give N‐protected amino acyl resin esters free of quaternary ammonium sites or reactive chloride.
Reinvestigation of the Classical Synthesis of Cinchona Alkaloids. II. The synthesis of quinine and its naturally occurring diastereomers from quinotoxine
Authors: Gutzwiller Jürg , Uskoković Milan R. 
Published: December 2004

AbstractStereoselektive Synthesen der Cinchona Alkaloide Chinin (6) und seiner natürlich vorkommenden Diastereomeren 7, 8 und 9, ausgehend von Chinotoxin (2), werden beschrieben. Reduktion der Ketone 4 und 5 mit DIBAL ergibt ausschliesslich die C(8)–C(9) erythro‐Verbindungen Chinin und Chinidin, während Reduktion von 5 mit Natriumborhydrid ausnahmslos zu den epi‐Verbindungen 8 und 9 führt. Die letztgenannten Verbindungen werden selektiv auch auf einem anderen Weg über die erythro‐Epoxide 20 und 21 erhalten.
Modellreaktionen zur Biosynthese von Verbindungen der Damascon‐Reihe und ihre präparative Anwendung
Authors: Ohloff Günther , Rautenstrauch Valentin , Schulte‐Elte Karl H. 
Published: December 2004

AbstractWe report a new general synthesis of damascones. In the presence of acids, 7, 8‐dehydro‐β‐ionole (10) or the related diols 11 are converted into a mixture of β‐damascone (2) and the 7, 8‐dehydrotheaspiranes (19). In the same way the 6‐hydroxy‐7, 8‐dehydro‐α‐ionoles 12 are transformed into a mixture of β‐damascenone (3) and the 8‐oxatheaspiranes (20). The reaction Provides access to damascone derivatives 4–7 which have been found in nature.These synthetic experiments lend support to our hypotheses concerning the biogenesis of damascones from suitable carotenoids or their metabolites.
C(8) Epimeric 8‐Hydroxy‐erythromycins‐B
Authors: Kurath Paul , Martin Jerry R. , Tadanier Jack , Goldstein Alma W. , Egan Richard S. , Dunnigan Daniel A. 
Published: December 2004

AbstractDie gepufferte m‐Chlorperbenzoesäure‐Epoxydation von 8, 9‐Anhydroerythromycin‐B‐6, 9‐hemiacetal liefert nach der Reduktion der N‐Oxidgruppe stereoselektiv das (8S, 9S)‐8, 9‐Anhydro‐erythromycin‐B‐6, 9‐hemiacetal‐8, 9‐epoxid nebst einer geringen Menge des 8‐epi‐(8 R, 9R)‐8, 9‐Anhydro‐erythromycin‐B‐6, 9‐hemiacetal‐8, 9‐epoxids. Die beiden Epoxide reagieren in wässeriger Essigsäure‐Lösung unter Wasseranlagerung stereospezifisch zum entsprechenden (8S)‐8‐Hydroxy‐erythromycin‐B, beziehungsweise zum 8‐epi‐(8R)‐8‐Hydroxy‐erythromycin‐B.
Synthese und Eigenschaften einiger neuer Mono(π‐cyclopentadienyl)‐Nickel‐Komplexe
Authors: Harder Viktor , Werner Helmut 
Published: December 2004

AbstractDuring studies on the mechanism of ligand displacement reactions of nickelocene non‐ionic monocyclopentadienylnickel complexes of the type πC5H5Ni[P(OP)3]X with X = Cl and P(O) (OR)2 have been obtained. The new compounds have been characterised by means of their IR., UV., NMR. and Mass spectroscopic data. The phosphonate ligands are bonded with the phosphorus atom to the transition metal.
Thermische Zerfallsreaktionen von Nitroverbindungen in Stosswellen. III: Dissoziation von 1‐Nitropropan und 2‐Nitropropan
Authors: Glänzer K. , Troe J. 
Published: December 2004

AbstractThe pyrolysis of 1‐ and 2‐nitropropane highly diluted in Ar has been studied in shock waves at temperatures K 915 < T < 1200 K and total gas concentrations 7 · 10−6 mol cm−3 < [Ar] < 1.5 · 10−4 mol cm−3. The reactions behind the shock waves have been followed by recording light absorption‐time profiles of the decomposing molecules and the produced NO2 Under the conditions of the experiments, the primary reaction step in both cases is the CN bond:fission: \documentclass{article}\pagestyle{empty}\begin{document}$ \begin{array}{rcl} {\rm 1} - {\rm C}_{\rm 3} {\rm H}_{\rm 7} {\rm NO}_{\rm 2} {\rm (} + {\rm M)} &\to & n - {\rm C}_{\rm 3} {\rm H}_{\rm 7} + {\rm NO}_{\rm 2} {\rm (} + {\rm M)\quad k} = 2.3 \cdot 10^{15} {\rm exp }(- 55{\rm kcal mol}^{ - 1} /{\rm RT}){\rm s}^{ - 1} \\ 2 - {\rm C}_{\rm 3} {\rm H}_{\rm 7} {\rm NO}_{\rm 2} {\rm (} + {\rm M)} &\to & i - {\rm C}_{\rm 3} {\rm H}_{\rm 7} + {\rm NO}_{\rm 2} {\rm (} + {\rm M)\quad k} = 2.4 \cdot 10^{15} {\rm exp }(- 54{\rm kcal mol}^{ - 1} /{\rm RT}){\rm s}^{ - 1} \\ \end{array} $\end{document} (first order rate constants k measured at concentrations of [Ar] ≃ 10−4 mol cm−3).At these concentrations the reactions are near to the high pressure limit. By varying the Ar‐concentrations over one order of magnitude, only a slight pressure dependence was found. Reaction mechanisms which account for NO2 removal are discussed.
Nuclear Quadrupole Resonance and Stereochemistry I. α – Chloro ethers
Authors: Ardalan Ziba , Lucken Edwin A. C. 
Published: December 2004

Abstract35Cl nuclear quadrupole resonance spectra of cyclic α‐chloro ethers of known configuration are presented. The resonance frequencies of chlorine atoms in equatorial positions are in every case some 2.5 MHz higher than those of corresponding chlorine atoms in axial positions. Similar results are obtained for open‐chain trichloromethyl ethers and the effect is sufficiently well‐defined to distinguish between configurational isomers and establish their conformation. These results may be rationalised in terms of a model in which the lone‐pair electrons on the oxygen atom hyperconjugate with the electrons of the CCl bond.
Le mécanisme de la réduction polarographique des dérivés ditosyloxylés et son implication en électrochimie préparative
Authors: Gerdil Raymond 
Published: December 2004

AbstractThe cleavage of a single SO2O bond occurs during the polarographic reduction of a tosyloxy group (pCH3C6H4SO2O = TsO) in aprotic medium and intramolecular cyclisation may ensue when a second TsO group is present on the same molecule. The polarographic behaviour of aliphatic ditosyloxy derivatives is discussed on the assumption that oriented vicinal derivatives at the interface assume a conformation which resembles the geometry of the transition state for an intramolecular elimination with anchimeric assistance of one of the tosyloxy groups. This situation favours the electron transfer, whereas the same geometric requirements hinder the intramolecular interaction of the TsO groups of the oriented non‐vicinal derivatives. This interpretation agrees well with the fact that the large scale electrolysis of vicinal ditosyloxy derivatives give much higher yield of cyclic ethers than the higher homologues. It is also shown that intramolecular interaction between TsO groups can occur through an intervening double bond in a non‐vicinal derivative.