bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bromdioxid: Spektroskopische Eigenschaften des Radikals
Authors: Bossy J. M. , Leoni M. W. , Bühler R. E. 
Published: December 2004

AbstractPulse radiolysis of oxygen‐saturated bromobenzene yields a transient absorption with λmax = 480 nm at pulse end, which is identified as due to the BrO2‐radical. To confirm this assignment the same radical was produced by flash photolysis of a Br2/O2‐gas mixture and by chemical synthesis at low temperature. The absorption spectra of these BrO2‐samples present a maximum between 480 and 380 nm dependent on the solvent. The influence of complex‐formation on this absorption band is discussed. The ESR.‐spectrum of chemically synthesized BrO2 is given.
Zur Diazotierung aromatischer Amine in Schwefelsäure
Authors: Konecny J. , Wenger H. 
Published: December 2004

AbstractThe diazotization of 2‐chloro‐4,6‐dinitroaniline, 2,6‐dichloro‐4‐nitroaniline, and 4‐nitroaniline in concentrated sulfuric acid is very strongly catalysed by water. At a given water concentration the reaction rates of these amines are in the ratio 50/20/1. The relation between the bimolecular rate constants k and the acidity function H0 is very simple, the plots of log k versus H0 being linear with a slope of 2.
Anil‐Synthese. 5. Mitteilung. Über eine neue Basen‐katalysierte Umlagerung von 4‐(Benzyl‐alkyl‐amino)‐4′‐styryl‐azobenzolen zu 4‐Benzoyl‐4′‐styryl‐azobenzolen
Authors: Weickhardt B. , Siegrist A. E. 
Published: December 2004

Abstract4‐(Benzyl‐alkyl‐amino)‐4′‐methyl‐azobenzole ergeben mit Anilen aromatischer Aldehyde in Dimethylformamid in Gegenwart von Kaliumhydroxid bei 40–45° Styrylderivate; bei höheren Temperaturen kann als Folge‐Reaktion deren Benzylalkylaminogruppe sich unter Oxydation zu einer N‐Alkyl‐benzimidoyl‐Gruppe umlagern, die durch anschliessende saure Hydrolyse in den Benzoylrest übergeht.
Temperaturabhängigkeit der Ultraviolett‐Spektren von H2O2 und von HO2‐Radikalen
Authors: Kijewski H. , Troe J. 
Published: December 2004

AbstractThe absorption spectra of H2O2 and of HO2 radicals have been investigated in shock waves at 1950 ⩽ λ ⩽ 2900 Å and temperatures of 650 and 1100 K. By comparison with room temperature experiments, information on the nature of electronic transitions involved may be obtained.
Photoelectron Spectra of Azabenzenes and Azanaphthalenes: I. Pyridine, diazines, s‐triazine and s‐tetrazine
Authors: Gleiter R. , Heilbronner E. , Hornung V. 
Published: December 2004

AbstractThe experimental and theoretical basis of a recently proposed reassignment of the bands in the PE. spectra of pyridine, pyridazine, pyrimidine and pyrazine is discussed in detail. A characteristic feature of the derived orbital sequence is that it takes the ‘through‐space’ and ‘through‐bond’ interaction between the ‘lone pair’ basis orbitals explicitly into account. A simple parametrization of the orbital energies, based on HMO‐type models for the π‐orbitals and for the ‘lone pair’ linear combinations, yields excellent agreement with the observed band positions in the PE. spectra of s‐triazine and s‐tetrazine. Our new assignment is compared to those proposed previously.
Notiz über die Photoelektronen‐Spektren des Nortricyclens und des Triasterans
Authors: Haselbach E. , Heilbronner E. , Musso H. , Schmelzer A. 
Published: December 2004

AbstractThe photocelectron spectra of nortricyclene (=tricyclo[2.2.1.02,6]heptane) and of triasterane (=tetracyclo[3.3.1.02,8.04,6]nonane) have been recorded and a tentative assignment of the bands has been put forward on the basis of MINDO/2 SCF calculations.
Antigen Synthesis: The Preparation of Selected Dodecapeptide Carriers with Systematically Altered Structures by a Two‐Phase Method
Authors: Schneider C. H. , Wirz W. 
Published: December 2004

AbstractThe synthesis of a series of dodecapeptide ethyl esters containing L‐leucine, L‐ala‐nine, glycine and L‐lysine is described. These peptides are suitable carriers for the preparation of haptenic conjugates to be used in antigenicity studies. The strategy for preparing intermediary hexapeptides has been called a two‐phase approach since the elongation of the peptide chain is carried out stepwise in a water‐immiscible organic phase, whereas removal of side‐products and excess reagent is effected by means of a suitably adapted aqueous phase. The method allows an efficient production of relatively large amounts of fully defined peptide antigens.
Le blocage de la lysine par la réaction de Maillard. II. Propriétés chimiques des dérivés N‐(désoxy‐1‐D‐fructosyl‐1) et N‐(désoxy‐1‐D‐lactulosyl‐1) de la lysine
Authors: Finot P. A. , Mauron J. 
Published: December 2004

AbstractLysine is often inactivated by ‘Maillard‐type’ reactions in food proteins; the values obtained for it by different methods cannot be compared because the chemical behaviour of inactivated lysine is unknown. In this paper, the behaviour of an important form of inactivated lysine, namely its 1‐deoxyketosyl derivatives, during acid hydrolysis as well as on the different assays for available lysine (F‐DNB, TNBS, pipsylchloride and guanidination) is studied. The relative proportions of regenerated lysine and of formed furosine and pyridosine are established as a function of the conditions of hydrolysis. The validity of the methods used to estimate available lysine from its 1‐deoxyketosyl derivatives is discussed.
Phénylhalogénohydrodigermanes
Authors: Rivière Pierre , Satgé Jacques 
Published: December 2004

AbstractThe symmetric and unsymmetric phenylchlorohydrodigermanes can be isolated or characterized via partial halogenation of the GeH bonds of the symmetrical phenylhydrodigermanes Ph2(H)GeGe(H)2Ph, Ph(H)2GeGe(H)2Ph by chloromethyl methyl ether and carbontetrachloride. Some of these phenylchlorohydrodigermanes are formed by insertion of phenylchlorogermylene (PhGeCl) on the GeH or GeCl bonds of the phenylchlorohydrogermanes.The hydrolysis of the monochloro phenylhydrodigermanes Ph2(Cl)GeGe(H)2 and Ph(Cl)(H)GeGe(H)2Ph leads to the phenyl phenylhydrogermyl digermoxanes [Ph2(H)GeGePh2]2O and [Ph(H)2GeGe(H)Ph]2O. Treatment of these oxides with the concentrated aqueous solutions of hydracides leads to the monofluorinated, brominated and iodinated phenylhydrodigermanes Ph2(H)GeGe(X)Ph2 and Ph(H)2GeGe(H)(X)Ph (X) = F, Br, I).Phenylchlorohydrodigermanes decompose thermally by α‐elimination on one germanium atom with formation of germylene and phenylchlorohydrogermane.The physico‐chemical IR. and NMR. study of these phenylhalogenohydrodigermanes indicates that, if the vGeH frequency variations are mostly linked to the inductive effects of the substituents on the same germanium, the variations of the chemical shifts of the GeH protons seem to be due to many factors and especially to the inductive effect of the substituents on the germanium and the magnetic anisotropy of the GeX bonds.
Die Synthese von menschlichem adrenocorticotropem Hormon (αh‐ACTH) mit revidierter Aminosäuresequenz
Authors: Sieber P. , Rittel W. , Riniker B. 
Published: December 2004

AbstractWe demonstrated recently that the amino acid sequence of human ACTH (αh‐ACTH1) differs in four positions from the structure reported in 1961 by Lee and coworkers. The synthesis of the revised sequence and a method of verifying the identity of the synthetic peptide with the naturally occurring hormone are described. The two preparations can most readily be compared by examining the mixture of fragments obtained upon degradation with trypsin. In this mixture, fragments 22–39 of natural αh‐ACTH and of the synthetic peptide are identical and easily distinguishable from the corresponding synthetic fragment of the previously postulated sequence. This is demonstrated by thin layer‐chromatography and ‐electrophoresis as well as by reference to the rate of deamidation under alkaline conditions.
α,β‐Epoxyketon → Alkinon‐Fragmentierung II: Pyrolytischer Zerfall der Hydrazone aus α,β‐Epoxyketonen und N‐Amino‐aziridinen. Über synthetische Methoden, 4. Mitteilung
Authors: Felix Dorothee , Müller Robert K. , Horn U. , Joos R. , Schreiber J. , Eschenmoser A. 
Published: December 2004

AbstractNumerous examples illustrate the course of the thermolysis of hydrazones derived from α,β‐epoxyketones and 2‐phenyl‐ or trans‐2,3‐diphenyl‐1‐amino‐aziridines. This process constitutes a preparatively useful method for the fragmentation of α,β‐epoxyketones to acetylenic carbonyl compounds including acetylenic aldehydes.Monohydrazones from phenylglyoxal and substituted N‐amino‐aziridines decompose smoothly and stereospecifically to the corresponding olefins and diazoacetophenone; such a process might also be useful for the preparation of other α‐diazocarbonyl compounds.
Steroid Total Synthesis, Part VII; (±)‐estr‐4‐ene‐3, 17‐dione and (±) 13β‐ethyl‐gon‐4‐ene‐3, 17‐dione
Authors: Rosenberger M. , Duggan A. J. , Saucy G. 
Published: December 2004

AbstractAn efficient and practical synthesis of the title compounds is described. The novel route is based on earlier results and uses (±)‐5‐hydroxy‐9,9‐o‐phenylenedioxy‐decanoic acid lactone as the starting material. The results demonstrate the usefulness of pyrocatechol for the protection of an aliphatic ketone.
A Chemical Study of Burley Tobacco Flavour (Nicotiana tabacum L.). II. Medium‐Volatile, free Acidic Constituents (b.p. ∼84–114°/0.001 Torr)
Authors: Demole Edouard , Berthet Dominique 
Published: December 2004

AbstractThe acidic part of a fraction b.p. 84–114°/0.001 Torr from Burley Tobacco condensate was investigated. Among the 22 compounds identified, 9 appeared to be new tobacco flavour components. This result increased to 208, the total number of Burley tobacco constituents so far isolated and identified in this laboratory.
Stabilité des paires ioniques europium et terbium‐iodate, bromate et chlorate
Authors: Roulet R. , Chenaux R. 
Published: December 2004

AbstractThe stability constants of ion pairs formed in aqueous solution between europium, terbium and iodate, bromate and chlorate have been determined by a liquid‐liquid extraction technique. These inorganic anions form 1:1 outer sphere complexes, as indicated by negative entropies of formation.
Conformational Studies of Cyclic Pentapeptides by Proton Magnetic Resonance Spectroscopy
Authors: Meraldi J. P. , Schwyzer R. , Tun‐Kyi A. , Wüthrich K. 
Published: December 2004

AbstractThe proton magnetic resonance spectra of c‐(‐Gly‐L‐Ala‐Gly‐Gly‐L‐Pro‐) (I) and four analogous cyclopentapeptides are presented. At ambient temperature the spectra contain two sets of resonances which correspond to two different molecular conformations of the peptides. The relative concentrations of the two forms depend on the peptide, the solvent, and the temperature. For the two molecular species of peptide I in DMSO solution, the NMR. data imply that the peptide linkage involving the nitrogen of proline is respectively in the cis‐ and the trans‐form, and both conformations contain intramolecular hydrogen bridges. Replacement of L‐alanine in I by L‐cysteine leaves the molecular conformations essentially unalteed. On the other hand substitution of L‐proline by L‐proline, or replacement of the two glycines in positions 3 and 4 by two sarcosyl residues gives rise to markedly different types of peptide backbone conformation.
Heuristic Programming as an Ion Generator in Mass Spectrometry. I. Generation of Primary Ions with Charge Localization
Authors: Delfino Allan B. , Buchs Armand 
Published: December 2004

AbstractUn programme connu sous le nom de ION GENERATOR a été élaboré. Pour le moment ce programme est capable de créer, à partir de n'importe quelle molécule organique, les ions primaires résultant de la tragmentation de l'ion moléculaire et de proposer des mécanismes de fragmentation pour expliquer la formation des ions.
The Mechanism of the Acid‐catalysed Hydrolysis of 1‐Aryl‐2,2,2‐trifluorodiazoethanes
Authors: Diderich Georges 
Published: December 2004

AbstractThe rates of the acid‐catalysed hydrolysis of a series of 1‐aryl‐2,2,2‐trifluorodiazoethanes la‐d have been measured in dioxan/water/HClO4. The results are well correlated with the Hammett equation when σp substituent constants are used (ϱH = −1.74 and ϱD = −1.75). Kinetic solvent isotope effects, about 2.1, and general acid catalysis indicate that proton transfer is rate‐determining (A‐SE2 mechanism). Rate measurements have also been made at pressures up to 1400 atm. The evaluated activation volumes, about −20 cm3/mole, indicate that at least one water molecule is bound in the transition state of protonation. Rate measurements at low water concentrations indicate that no apparent change in mechanism has occured.
Exchange Equilibrium of Oxygen Isotopes between BrO, ClO, IO and Water
Authors: Agarwal S. C. , Baertschi P. , Gamsj H. 
Published: December 2004

AbstractThe liquid phase fractionation factors αH = (18O/16O)H2O/(18O/16O)xo and αD = (18O/16O)D2O/(18O/16O)xo (X = Cl, Br, I) were calculated quantum mechanically between 0 and 100°. Experimental values were obtained in the case of BrO at 60° showing good agreement with the calculated results.
Isolierung von 11α, 11′α‐Dihydroxychaetocin aus Verticillium tenerum
Authors: Hauser D. , Loosli H. R. , Niklaus P. 
Published: December 2004

AbstractBased on 13C‐NMR. and other physico‐chemical evidence, the structure of 11α, 11′α‐dihydroxychaetocin (3) has been assigned to a new antibacterial and antimitotic metabolite, isolated from the fungus Verticillium tenerum.
α‐Chlor‐nitrone II: Eine Methode zur Darstellung von γ‐Lactonen aus Olefinen. Über synthetische Methoden, 6. (vorläufige) Mitteilung
Authors: Das Gupta T. K. , Felix Dorothee , Kempe U. M. , Eschenmoser A. 
Published: December 2004

AbstractThe addition products obtained by the Ag+‐induced reaction of α‐chloro‐aldonitrones with olefins (see preceding communication) can be utilized efficiently for making γ‐lactones (see scheme 1).
Studies in the Helicene Series NMR. Evidence of ‘Helicene‐like’ Conformations in the cis 1,2‐Diarylethylenes. Part XVII
Authors: Martin R. H. , Defay Nicole , Figeys H. P. , Lê van K. , Ruelle J. J. , Schurter J. J. 
Published: December 2004

AbstractThe cis and trans isomers of eight 1,2‐diarylethylenes, precursors of helicenes, have been studied by NMR. spectroscopy. The observed differences in chemical shifts, specific solvent effects and steric effects (bromo derivatives) can be explained by the contribution of ‘helicenelike’ conformers in the cis isomers.
Reaction of 2‐Methylenenorbornane with N‐Bromosuccinimide
Authors: Jefford C. W. , Wojnarowski W. 
Published: December 2004

AbstractThe reaction of 2‐methylenenorbornane with N‐bromosuccinimide produced a mixture of six monobromides in an overall yield of about 60%. By irradiation in the presence of benzoyl peroxide exo‐ and endo‐3‐bromo‐2‐methylenenorbornanes, 2‐bromomethylnorborn‐2‐ene, Z‐ and E‐2‐bromomethylenenorbornanes and 1‐bromomethylnortricyclene were found in a percentage ratio of 43.0, 7.5, 6.5, 19.0, 19.0 and 5.0. Without benzoyl peroxide, in the dark, the same products were obtained, but in a percentage ratio of 23.0, 3.0, 17.0, 26.0, 26.0 and 7.0. These results are rationalized in terms of an ionic mechanism in concurrence with some radical mechanism contribution.
The Migratory Aptitude of the Ethoxycarbonyl Group in the Pinacol Rearrangement. Preliminary communication
Authors: Kagan Jacques , Agdeppa Dalmacio A. , Singh S. P. 
Published: December 2004

AbstractThe migratory aptitude of the ethoxycarbonyl group in the pinacol rearrangement was deduced from the structure of the products observed after treatment of 2‐substituted 2,3‐dihydroxy‐3‐phenylbutyrates with fluorosulfonic acid at 0° for 3 minutes. The migratory aptitude of ethoxycarbonyl is comparable to that of ethyl, greater than that of methyl or hydrogen, but smaller than that of phenyl. Cyclization and fragmentation reactions were also observed.
Amino‐nucléosides III. Dérivés des amino‐3‐didésoxy‐3,5‐D‐lyxo et D‐ribo‐pentoses
Authors: Tronchet J. M. J. , Graf R. 
Published: December 2004

AbstractThe 3‐amino‐3,5‐didesoxy‐1,2‐O‐isopropylidene‐α‐D‐ribofuranose and ‐β‐D‐lyxo‐furanose and several derivatives thereof have been prepared by hydride reduction of the corresponding oximes.
Anil‐Synthese. 7. Mitteilung.. Über die basenkatalysierte Umsetzung von methylsubstituierten 2‐Phenyl‐2H‐benzotriazolen mit Anilen aromatischer Aldehyde
Authors: Siegrist A. E. , Zweidler R. 
Published: December 2004

Abstract2‐(p‐Tolyl)‐2H‐benzotriazole und 2‐Phenyl‐5‐methyl‐2H‐benzotriazole können mit Anilen aromatischer Aldehyde in Dimethylformamid in Gegenwart von Kaliumhydroxid in 2‐(Stilben‐4‐yl)‐2H‐benzotriazole bzw. 2‐Phenyl‐5‐styryl‐2H‐benzotriazole über geführt werden («Anil‐Synthese»). Durch Einführung von Substituenten wie Chlor oder Methoxy gruppen kann die Lage des Fluoreszenzspektrums in Dimethylformamid eine erhebliche batho chrome oder hypsochrome Verschiebung erfahren.
Germa‐2‐dioxa‐1,3‐cycloalcanes
Authors: Satgé J. , Dousse G. 
Published: December 2004

AbstractThe action of the α‐, β‐ and γ‐diols on the dialkyl(aryl)‐bis(dialkylamino) germanes R2Ge(NR'2)2 leads, in high yields, to the dialkyl(aryl)‐2,2‐germa‐2‐dioxa‐1,3‐cycloalkanes.The IR. and NMR. spectral study in the presence of Eu(Dpm)3 allowed to demonstrate a dimerisation by coordination in some of these heterocycles. In this complex, the germanium is hexacoordinated by association with the two oxygens of the second associate molecule. Its hybridation state is sp3d2 or spd4 (D3h symmetry, prismatic structure).These low energy association are ruptured in solution at moderate temperatures; these heterocycles are monomers by ebulliometry in benzene.This association is disfavoured by the presence of substituents on the cycle and by hindering substituents with donor effect on the germanium.The diminution of nucleophilicity of the oxygens by mesomeric effect with neighbouring π systems also prevents any association.
The Photoelectron Spectra of NSCl, NSF and NSF3
Authors: Cowan D. O. , Gleiter R. , Glemser O. , Heilbronner E. 
Published: December 2004

AbstractThe photoelectron spectra of NSCl and NSF3 have been recorded. By comparison with the PE.‐bands of NSF and semiempirical calculations the first bands of NSCl and NSF3 are assigned.
Intracatenare Vernetzung von Gelatine mit Carbodiimid
Authors: Gardi A. , Nitschmann Hs. 
Published: December 2004

AbstractUnder suitable conditions it is possible to introduce into dissolved denatured gelatin molecules intracatenar cross‐links. Working with 2% solutions of commercial gelatin (Mn approximately 40000) at 40° and pH 5,75 and with water‐soluble carbodiimid as a condensing agent we succeeded in inserting 7–8 intracatenar amide bonds per molecule. The number of cross‐links introduced was determined by the decrease of free NH2 and COOH groups.Using 4% solutions a gel melting point of the cross‐linked preparations below 0° was obtained as compared with the gel melting point of untreated gelatin at 28°.The low viscosity and the behaviour in gel chromatography on Sepharose 6B show that the cross‐linked peptide chains are fixed as rather dense coils.A small amount of the cross‐linking reagent remains covalently bound to the protein, as was shown with tritium labeled carbodiimid. The side reactions possibly responsible for this occurrence are discussed. The bonds between reagent and gelatin are fairly stable at acidic pH, but labile at alkaline pH.The results of optical measurements (UV. and CD.) on cross‐linked gelatin will be reported in another paper.
9‐Methyl‐cis‐decalin‐1,3‐dion: Stereochemische Untersuchungen an 9‐Methyl‐cis‐decalin‐Derivaten. 5. Mitteilung über cyclische β‐Diketone
Authors: Zurflüh R. , Tamm Ch. 
Published: December 2004

AbstractThe synthesis and the spectral properties of the hitherto unknown 9‐methyl‐cis‐decalin‐1,3‐dione (16) are described. The keto‐enol equilibrium of 16 in various solvents was determined by NMR. spectroscopy. The configuration and conformation of a large number of intermediates and derivatives were determined.
Neue β‐Lactam‐Antibiotika. Über die Darstellung der 8‐β‐Phenylacetamido‐homoceph‐4‐em‐5‐carbonsäure (1). Modifikationen von Antibiotika, 7. Mitteilung
Authors: Scartazzini R. , Gosteli J. , Bickel H. , Woodward R. B. 
Published: December 2004

AbstractThe thiazolidine β‐lactam 3 adds acrolein in a Michael type reaction. The resulting 'carbinolamide 4 is converted to 8‐β‐phenylacetamido‐homoceph‐4‐em‐5‐carboxylic acid (1) by previously described methods.
Pseudoasymmetrie in der organischen Chemie
Authors: Prelog V. , Helmchen G. 
Published: December 2004

AbstractThe geometrical foundations of ‘pseudoasymmetry’ and several other related concepts of organic stereochemistry such as ‘prochirality’ and ‘propseudoasymmetry’ in two‐ and three‐dimensional space have been explored. As a consequence some modifications of the R,S system for specification of molecular chirality and stereoisomerism are proposed.
Umlagerung von Allyl‐aryläthern und Allyl‐cyclohexadienonen mittels Bortrichlorid
Authors: Borgulya J. , Madeja R. , Fahrni P. , Hansen Hans‐Jürgen , Schmid Hans , Barner R. 
Published: December 2004

AbstractAllyl aryl ethers which have no strongly electron attracting substituents undergo a charge‐induced [3 s, 3 s] sigmatropic rearrangement in the prescence of 0.7 mole boron trichloride in chlorobenzene at low temperature, to give after hydrolysis the corresponding o‐allyl phenols (Tables 1 and 2). The charge induction causes an increase in the reaction rate relative to the thermal Claisen rearrangement of ∼1010. With the exception of allyl 3‐methoxyphenyl ether (5), m‐substituted allyl aryl ethers show similar behaviour (with respect to the composition of the product mixture) to that observed in the thermal rearrangement (Table 3). The rearrangement of allyl aryl ethers with an alkyl group in the o‐position, in the prescence of boron trichloride, yields a mixture of o‐ and p‐allyl phenols, where more p‐product is present than in the corresponding product mixture from the thermal rearrangement (Table 4). This ‘para‐effect’ is especially noticeable for o‐alkylated α‐methylallyl aryl ethers (Table 5 ).With boron trichloride, 2,6‐dialkylated allyl aryl ethers give reaction products which arise, in each case, from a sequence of an ortho‐Claisen rearrangement followed by a [1,2]‐, [3,3]‐ or [3,4]‐shift of the allyl moiety (Tables 6 and 7). Ally1 mesityl ether (80), with boron trichloride, gives pure 3‐ally1 mesitol (95). From phenol, penta‐ally1 phenol (101) can be obtained by a total of five O‐allylations followed by three thermal and two boron trichloride‐induced rearrangements.The sigmatropic rearrangements of the ethers studied, using D‐ and 14C‐labelled compounds, are collected in scheme 2; only the reaction steps indicated by heavy arrows are of importance.With protic acids, there is a [3,3]‐shift of the allyl group in 6‐allyl‐2,6‐disubstituted cyclohexa‐2,4‐dien‐l‐ones, while with boron trichloride the [3,3]‐reaction is also observed along with the much less important [1,2]‐ and [3,4]‐transformations (Table 8). 4‐Allyl‐4‐alkyl‐cyclohexa‐2,5‐dien‐1‐ones give only [3,3]‐rearrangements with boron trichloride (Table 9). As expected, the naphthalenone 112, which is formed by allowing boron trichloridc to react for a short time with allyl (1‐methyl‐2‐naphthyl) ether (111), undergoes only a [3,4] rearrangement (Scheme 3).Representations of how, in our opinion, the complex behaviour of allyl aryl ethers and allyl cyclohexadienones under the influence of boron trichloride, can be rationalized are collected together in Schemes 4 and 5.In the last part of the discussion section, the steric factors leading to the appearance of the ‘para‐effect’, are dealt with (Scheme 6).