bluuebunny/crossref_metadata_2025_split huggingface dataset:
Die Chukrasine A, B, C, D und E, fünf neue Tetranortriterpene aus Chukrasia tabularisA. JUSS
Authors: Ragettli Thomas , Tamm Christoph 
Published: December 2004

The Chukrasines A, B, C, D and E, Five New Tetranortriterpenes From Chukrasia tabularis A. JUSSFive new tetranortriterpenes, chukrasins A, B, C, D and E, have been isolated from the wood of Chukrasia tabularis A. JUSS. On the basis of spectral and chemical evidence structures 1a‐1e were assigned to the new compounds.
Influence of Imidazole and Hydrocyanic Acid Derivatives on the ‘Possible Prebiotic’ polyphosphate induced peptide synthesis in aqueous solution
Authors: Rabinowitz Joseph , Hampai Aioub 
Published: December 2004

AbstractGlycine in aqueous solutions of trimetaphosphate or linear polyphosphate at pH adjusted to 8.1‐9.0, is condensed at room temperature to diglycine and very small amounts of triglycine. The addition of imidazole increases the yield of triglycine by a factor of almost 10; supplementary addition of magnesium ion does not increase this effect. On the contrary to what has been observed at pH 11.5‐12.0, the addition of sodium cyanide or cyanamide at pH 8.1‐9.0 diminishes strongly the yield of triglycine and to a lesser degree that of diglycine. The prebiotic significance of the condensation of amino acids in aqueous solutions of polyphosphates in the presence of imidazole is discussed.
Absolute Konfiguration von α‐Doradexanthin und von Fritschiellaxanthin, einem neuen Carotinoid aus Fritschiella tuberosa IYENG
Authors: Buchecker Richard , Eugster Conrad Hans , Weber Adolf 
Published: December 2004

Absolute Configuration of α‐Doradexanthin and of Fritschiellaxanthin, a New Carotenoid from Fritschiella tuberosa IYENG.Fritschiellaxanthin, a new oxocarotenoid produced by the green alga Fritschiella tuberosa, in a nitrogen‐deficient medium is now shown to be (3 S, 3′ R, 6′ R)‐3, 3′‐dihydroxy‐β, ϵ‐caroten‐4‐one (4b). It is not identical with α‐Doradexanthin (5b) previously found in goldfish (Carassius auratus) and to which we assign the (3 S, 3′ S, 6′ R)‐chirality. Consequently, fritschiellaxanthin and α‐Doradexanthin are C(3′)‐epimers of lutein‐4‐on. Furthermore, the so‐called ′lutein′ from goldfish has now been found to be identical with 3′‐epilutein (3). Therefore, fritschiellaxanthin is probably biogenetically derived from lutein (2), whereas α‐Doradexanthin is formed from 3′‐epilutein (3) with 3, O‐didehydrolutein (=(3R, 6′R)‐3‐hydroxy‐β, ϵ‐caroten‐3′‐one10) as a precursor. For comparison, optically active 10 and 3 have been prepared from lutein (2) and are fully characterised.
Extraktion von Alkali‐ und Erdalkalimetallpikraten aus wässerigen Lösungen in Methylenchlorid durch ungeladene azyklische Ionophoren. Quantitative Interpretation
Authors: Kirsch Norbert N. L. , Funck Robert J. J. , Simon Wilhelm 
Published: December 2004

Extraction of alkali and alkaline earth metal picrates from water into methylene chloride. Quantitative interpretationThe ligands N, N, N′, N′‐tetraphenyl‐3, 6‐dioxaoctanediamide (1), (−)‐(R, R)‐N, N′di [(ll ‐ ethoxycarbonyl) undecyl] ‐ N, N′, 4, 5‐tetramethyl‐3, 6‐dioxaoctanediamide (2), and N, N′‐diheptyl‐N, N′, 5,5‐tetramethyl‐3,7‐dioxanonanediamide (3), reported earlier as components for liquid membrane electodes with selectivity for Ba2+ (1), Ca2+ (2) and Li+(3), were used to study models for the extraction of alkali and alkaline earth metal picrates from water into methylene chloride. The composition of the extracted complexes of alkaline earth cations with 1 and 2 proved to be mono‐ and diassociated with the picrate anion. The extraction selectivity observed for 1, 2, and 3 towards different cations paralleled the potentiometric selectivity factors obtained for liquid membrane electrodes with 1, 2, and 3 as membrane components.
On the mechanism of the Hg2+ and base induced hydrolysis reactions of the β2‐(RR, SS)‐Co (trien) (glyOR)Cl2+ions (R = H, C2H5), evidence for the site of deprotonation in the reactive conjugate base
Authors: Buckingham David A. , Marty Werner , Sargeson Alan M. 
Published: December 2004

AbstractAcid hydrolysis of the ester function in Δ‐(−)589‐β2‐(RR)‐[Co (trien) (glyOEt) Cl]2+ ((−)‐1) produces optically pure Δ‐(−)589‐(RR)‐[Co (trien) (glyOH)Cl]2+ ((−)‐4). Hg2+ induced removal of chloride in (−)‐4 follows the rate law kobs = kHg [Hg2+] with kHg = (1.36 ± 0.03) × 10−2 M−1s−1, 25°, μ=1.0, and produces optically pure Δ‐(−)589‐β2‐(RR)‐[Co(trien) (glyO)]2+ ((−)‐2). Competition by NO occurs in this reaction ([NO], 1M, 3%) indicating a path whereby external nucleophiles (YNO, H2O) compete with the intramolecular carboxylate function for an intermediate of reduced coordination number. Rapid ring closure to 2 must ensue for Y  H2O. Base hydrolysis of chloride in (±)‐1 produces (±)‐2 together with its diastereoisomer β2‐(RS, SR)‐[Co(trien) (glyO)]2+, ((±)‐3), in which one secondary amine function has an inverted configuration. 2 and 3 incorporate 18O‐labelled solvent into the Co‐O position of the coordinated carboxylate moiety (2: 9.0%; 3: 12.3%) indicating that at least part of the product arises via intramolecular hydrolysis in β2‐hydroxo ethylglycinate intermediates (Fig. 4). Base hydrolysis of (−)‐4 follows the rate law Kobs = kOH[OH−] with kOH = (6.3 ± 0.6) × 10−4M−1 S−1, 25°, μ = 1.0 producing (−)‐2 (37‐45%) and (−)‐3 (63‐55%), the ratio being somewhat medium dependent. Competition by added N (1M) occurs using (±) ‐4 forming β2‐(RR, SS)‐[Co (trien) (glyO)N3]+ (∼2%) and β2‐(RS, SR)‐[Co (trien) (glyO)N3]+ (∼ 13%). Mutarotation at the secondary nitrogen centre is shown to occur after the rate determining loss of Cl− in 1 and 4 and before the formation of 2 and 3. It is concluded that this secondary nitrogen is the site of deprotonation in the reactive conjugate bases of 1 and 4, and possible mechanisms for the mutarotation process are considered.
Cyclometallierungsreaktionen an o‐Hydroxy‐diarylazoverbindungen
Authors: Stiner Eginhard , L'Eplattenier François A. 
Published: December 2004

Cyclometallation reactions of o‐Hydroxy‐diarylazocompoundsThe metallation of o‐hydroxy‐diarylazoligands with Pt(II)‐ or Pd (II)‐salts leads not only to the classical complexes of type 3 but also to coordination compounds of type 2, containing a metal‐carbon bond. The latter coordinate carbon monoxide, which can be inserted into the metal‐carbon bond, thus leading after reductive elemination of the metal to heterocyclic products.
Isolierung von (±)‐Tembamid aus Zanthoxylum tingoassuiba L. (Rutaceae)
Authors: Bernhard Heinz O. , Thiele Kurt 
Published: December 2004

Isolation of (±)‐Tembamid from the Bark of Zanthoxylum tingoassuiba L. (Rutaceae)Racemic tembamid (5) has been isolated from the bark, and (−)‐sesamin (1) from the leaves of Zanthoxylum tingoassuiba L.
Isolierung von 1‐Allyl‐2, 3‐dimethoxy‐4, 5‐methylendioxybenzol (= Dill‐Apiol)aus Heckeria umbellata (L.) Kunth (Piperaceae)
Authors: Bernhard Heinz O. , Thiele Kurt 
Published: December 2004

Isolation of 1‐Allyl‐2,3‐dimethoxy‐4,5‐methylenedioxybenzene from Heckeria umbellata (L.) KUNTH (Piperaceae)From the leaves of Heckeria umbellata (L.) KUNTH an oily substance was isolated and its structure deduced. It is 1‐allyl‐2, 3‐dimethoxy‐4, 5‐methylenedioxybenzene (= Dill‐Apiol; 2) and not as previously published 1‐allyl‐2, 5‐dimethoxy‐3, 4‐methylenedioxybenzene (= Apiol; 1) [2].
Racematspaltung und Bestimmung der absoluten Konfiguration von 2, 6‐disubstituierten Bicyclo [3.3.1]nonanen
Authors: Gerlach Hans 
Published: December 2004

Resolution and Determination of the Absolute Configuration of 2,6‐Disubstituted Bicyclo[3.3.1]nonanes(±)‐endo, endo‐Bicyclo [3.3.1]nonane‐2,6‐diol was resolved via diastereomeric camphanic acid esters. Conversion of the (+)‐enantiomer 2 via (+)‐5 and (+)‐6 as key intermediates gave (+) methyl 3‐(3‐oxocyclohexyl)‐propionate (7) which independently could be prepared also from the known (+)‐(R)‐3‐oxo‐cyclohexane‐carboxylic acid (8). These chemical correlations establish the absolute configuration of (+)‐2, (+)‐5 and (+)‐6 as well as that of (+)‐bicyclo [3.3.1]nonane‐2,6‐dione (1) obtained by oxidation of (+)‐2. The chiroptical properties of 1 and 6 are discussed.
Investigation on the Head‐Space of Roasted Meat. III. Synthesis of 4, 6‐dimethyl‐2,3,5,7‐tetrathiaoctane
Authors: Dubs Paul , Joho Martin 
Published: December 2004

AbstractA synthesis of 4, 6‐dimethyl‐2,3,5,7‐tetrathiaoctane (1), from 3,5‐dimethyl‐1,2,4‐trithiolane (6), is described. Compound 1, possessing a unique structure was recently found to be a constituent of roasted pork meat.
Photochemische Reaktionen. 99. Mitteilung. Photochemistry of N‐Acylimidazoles. IV. Structural Factors Leading to Norrish Type II Elimination and to Cyclobutanol Formation in the Photolysis of Acylimidazoles
Authors: Iwasaki Shigeo 
Published: December 2004

AbstractConformational factors leading to Type II elimination and to cyclobutanol formation were studied in the irradiation of N‐acylimidazoles with simple acyl groups as well as of their photochemical acyl migration products.
Absolute Configuration of Actinioerythrin
Authors: Müller Robert K. , Mayer Hans , Noack Klaus , Daly John J. , Tauber James David , Liaaen‐Jensen SynnøVe 
Published: December 2004

AbstractThe CD. correlation of (3 S, 3′S)‐and (3 R, 3′R)‐actinioerythrol diacetate, obtained by total synthesis from β‐ionone, with actinioerythrin isolated from the sea anemone Actinia equina L. shows that the natural compound has the (3 S, 3′S)‐configuration.
Photochemistry of 3‐Substituted 1‐Iminopyridinium Ylides. Regiospecific versus non‐regiospecific photoisomerization patterns [1]
Authors: Fritz Hans , Gleiter Rolf , Nastasi Michel , Schuppiser Jean‐Luc , Streith Jacques 
Published: December 2004

Abstract3‐Substituted 1‐iminopyridinium ylides 1 undergo photo‐induced ring enlargement to 1H‐1,2‐diazepines. With strongly electron‐withdrawing substituents the ring expansion process is regiospecific and leads exclusively to 4‐substituted 1 H‐1, 2‐diazepines. Weak electron‐donating substituents, like a methyl group and halogen atoms, do not have any directing effect since both 4‐ and 6‐substituted 1 H ‐1,2‐diazepines are obtained. With strong electron‐donating substituents no diazepines are formed; instead one observes photo‐induced isomerization to the 2‐aminopyridine derivatives, the process being non‐regiospecific. Regiospecific photo‐induced ring expansion processes are explained in terms of a simple HMO model.
Synthesis, Structure and Photochemical Properties of 4, 4′, 7, 7′‐Tetra‐substituted 1,1′, 3,3′‐Tetraethylbenzimidazolotriazatrimethine Cyanines
Authors: Naef Rudolf , Balli Heinz 
Published: December 2004

AbstractThe synthesis of sterically hindered 1,1′, 3,3′‐tetraethylbenzimidazolotriazatrimethine cyanine dyes, their electron absorption spectra and that of their photo‐products (inverse photochromism) is described. Kinetic data of the thermally reversed reaction of the photo‐bleached compounds are given. The differences of the electron absorption spectra in this series in this series of dyes are explained by the different degree of distortion of the π‐systems which is confirmed by an X‐ray investigation.
Zur Reaktionsweise von Diphenylcyclopropenon mit β‐Carbonyl‐enolaten. I. Einsatz von Acetylaceton, Acetessigsäure‐methylester, 2‐Äthoxycarbonyl‐cyclododecanon und Malonsäure‐dimethylester
Authors: Veprek‐Bilinski Vanda , Narasimhan Krishna , Dreiding André S. 
Published: December 2004

Reaction of Diphenylcyclopropenone with β‐Carbonyl‐enolates. I. Use of Acetylacetone, Methyl Acetoacetate, 2‐Ethoxycarbonyl‐cyclododecanone and Dimethyl MalonateThe reaction of the sodium salts of acetylacetone (6), methyl acetoacetate (7), 2‐ethoxycarbonyl‐cyclododecanone (8), dimethyl malonate (19) and its methyl derivative 20 with diphenylcyclopropenone (5) in dimethylformamide at room temperature led to the unsaturated γ‐lactones 14, 15, 17, 22 and 36. In the case of dimethyl malonate (19), the halfester 21, the acyl‐malonic ester 24 and the indenone‐malonic ester 23 were also isolated.Several intermediates and the final products were characterised by reactions and spectroscopically. A general mechanism is discussed for the addition of cyclo‐propenones (1) to the enolate salts of β‐dicarbonyl compounds 4 involving the bicyclic lactone‐enolates 18 and 32 as intermediates. The products formed via 18 and 32 are considered to be the result of an attack of one of the oxygen atoms of the β‐carbonyl‐enolate anion (4), the product 24, on the other hand, of the attack of the α‐carbon atom of 4; in both cases the attack is on the carbonyl C‐atom of 5.
Die Struktur der durch Halogenierung von Furfural in Wasser gebildeten Oxydationsprodukte
Authors: Greuter Hans , Winkler Tammo 
Published: December 2004

The Structures of the Oxidation Products formed by Hologenation of Furfural in WaterThe oxidation products formed on halogenating furfural in water are cis/trans‐2,5‐dihydroxy‐2‐(dihydroxymethyl)‐2,5‐dihydrofuran (5) and cis/trans‐2,6‐dihydroxy‐2 H‐pyran‐3 (6H)‐one (6) as shown by 1H‐ and 13C‐NMR.‐spectroscopy. A new, simple high‐yield preparation of 5‐ and 6‐ solutions is described, in which sodium bromate is used as the oxidizing agent.
13C‐NMR. Analysis of Dihydrogranaticin Methyl Ester. A case of mixed biogenesis
Authors: Arnone Alberto , Camarda Lorenzo , Cardillo Rosanna , Fronza Giovanni , Merlini Lucio , Mondelli Rosanna , Nasini Gianluca , Pyrek Jan St. 
Published: December 2004

AbstractThe 13C‐NMR. spectrum of dihydrogranaticin methyl ester has been completely analyzed. Feeding experiments of CH3 13COONa to a culture of Streptomyces olivaceus have shown that only a sixteen carbon moiety of the antibiotic granaticin is of polyketide origin, thus confirming the hypothesis of a mixed biogenesis for this natural substance.
Synthesis and Dimerization of Bicyclo [4.4.1] undec‐1 (11)‐ene, a Bridged trans‐Cycloheptene
Authors: Becker Konrad B. , Chappuis Jacques L. 
Published: December 2004

AbstractThe synthesis of bicyclo [4.4.1] undec‐1 (11)‐ene (5) by intramolecular Wittig reaction is described. The Bredt olefin could not be isolated, but dimerized rapidly to a novel compound 15 containing a cyclopropane ring. The olefin 5 was trapped in situ by 2,5‐diphenylbenzo [c]furan.
On the Synthesis and Characterization of Pd (CO) (PPh3)3
Authors: Morandini Franco , Consiglio Giambattista , Wenzinger Fritz 
Published: December 2004

AbstractPd (CO) (PPh3)3 could be isolated from the reaction mixture arising from cyclohexene hydrocarboxylation by PdCl2 (PPh3)2 as the catalyst precursor; furthermore, it has also been prepared through direct reaction of Pd (PPh3)4 with CO in benzene. For this complex, 31P‐ and 13C‐NMR. spectra suggest a rapid dissociation of PPh3 at room temperature and a tetrahedral structure at – 70° in solution.
1H‐ and 13C‐NMR. Studies of some metal complexes of o, o′‐dihydroxyazobenzenes
Authors: Pregosin Paul S. , Steiner Eginhard 
Published: December 2004

AbstractThe aromatic 1H‐ and 13C‐NMR. spectra of some metal complexes of o, o′‐dihydroxyazobenzenes are shown to be useful in distinguishing the two possible isomers (acolar and discolar) stemming from the non equivalence of the two ligating azo nitrogen atoms. The ortho aromatic carbon atoms, C(6) and C(12) experience relatively large upfield shifts between 12.8 and 15.7 ppm when the adjacent nitrogen atom is coordinated. The protons attached to these carbon atoms are shifted downfield. The values nJ (15N, 13C) for the ligand 2,2′‐dihydroxy‐3‐methyl‐4′‐chloro‐5‐(t‐butyl)‐15N‐azobenzene are reported.
Megastigma‐5,8‐dien‐4‐on, ein Aromastoff der gelben Passionsfrucht und des Virginia‐Tabaks
Authors: Demole Edouard , Enggist Paul , Winter Max , Furrer Anton , Schulte‐Elte Karl H. , Egger Bernard , Ohloff Günther 
Published: December 2004

Megastigma‐5,8‐dien‐4‐one, an aroma constituent of the yellow passion fruit and Virginia tobaccoPreparative gas chromatography allowed isolation of megastigma‐5, 8 (E)‐dien‐4‐one (3) from small subfractions of both yellow passion fruit and Virginia tobacco condensates. Along with 3, the Z‐isomer 4 occurs in the aroma of the yellow passion fruit. Both these novel flavor compounds were synthesized by a two‐step, non‐biomimetic route starting from 2, 6, 6‐trimethylcyclohex‐2‐en‐1‐one. The E‐isomer 3 was also formed by acid‐catalyzed dehydration/rearrangements of ionol‐ and damascol monoepoxides 5, 6, 7, 8 and hydroxy‐ionols and ‐damascol 9, 10 and 11. Such a biomimetic conversion indirectly supports the assumption that 3 and 4 might originate from the oxidative degradation of carotenoid precursors possibly related to canthaxanthine.
Reaktion von 3‐Amino‐2H‐azirinen mit Diphenylcyclopropenthion. Vorläufige Mitteilung
Authors: Chaloupka Stanislav , Heimgartner Heinz 
Published: December 2004

Reaction of 3‐Amino‐2H‐azirines with Diphenylcyclopropenethione3‐Dimethylamino‐2H‐azirines (4a, 4b) react with diphenylcyclopropenethione (8) to give 4(3 H)‐pyridinethione derivatives of type 10 (Scheme 3). The reaction mechanism for the formation of 10 is given in Scheme 3 by analogy with a previous reported one [4] [5]. Hydrolysis of the 4(3 H)‐pyridinethione 10a yields 2‐oxo‐2, 3‐dihydro‐4(1 H)‐pyridinethione (11) and reduction of 10a with sodium borohydride leads to the 2, 3‐dihydro‐4 (1 H)‐pyridinethione 12 (Scheme 4). The results of the reaction of 4a, 4b and the thione 8 demonstrate the similarity to the reaction of 4a, 4b and 2 [5] (cf. Scheme 1). In contrast, the reactions of imines of type 7a with 2 and 8, respectively, lead to different products (cf. [1] [6]).
Synthetische Verwendung von Epoxynitronen. I. N‐(2,3‐Epoxypropyliden)‐cyclohexylamin‐oxid, ein neues Reagens zur Synthese von α‐Methyliden‐γ‐lactonen aus Olefinen
Authors: Riediker Martin , Graf Walter 
Published: December 2004

Synthetic Application of Epoxynitrones I. Nitrone, a New α‐Methylidene‐γ‐lactone Annelating ReagentThe N‐(2, 3‐epoxypropyliden)‐cyclohexylamine‐N‐oxide/CF3SO3SiR3 reagent descried in this communication opens a new and interesting entry to the versatile N‐substituted N‐propenylnitrosonium ions of type b (Scheme 6). One of the uses of this reagent is shown to be the synthesis of α‐methylidene‐γ‐lactones from olefins. This new method shows similar features as the method based on 2, 3‐dichloropropylidenamine‐oxide/AgBF4 originally developed for the same purpose by Petrzilka, Felix and Eschenmoser.Epoxynitrone 18 can be transformed to the positively charged heterodiene of type b (Scheme 5) using the highly electrophilic reagents CF3SO3SiMe3 (23) and CF3SO3Si (t‐Bu)Me2 (24), respectively. Low temperature 1H‐ and 13C‐NMR. spectroscopy at −78° showed the sole formation of the nitrone‐O‐silyl‐ethers a (Scheme 5). Epoxid opening leading to the diene b and subsequent reactions are observed only at about −30°. The diene b prepared in situ, adds to isolated double bonds by way of an inverse Diels‐Alder reaction to afford cycloadducts of type 27 (Scheme 7). Their stable cyanoderivatives, e.g. 28 (Scheme 7), can be isolated and transformed via 31, 44 and 54 into cis annelated α‐methylidene‐γ‐lactones of type 55 (Scheme 11). Using trisubstituted olefins, substitution at the lower substituted olefinic C‐atom competes efficiently with the cycloaddition (e.g. 34, Scheme 8).
Zur Photochemie von 2, 1‐Benzisoxazolen (Anthranilen) und thermischen und photochemischen Umsetzungen von 2‐Azido‐acylbenzolen in stark saurer Lösung
Authors: Doppler Thomas , Schmid Hans , Hansen Hans‐Jürgen 
Published: December 2004

On the Photochemistry of 2, 1‐Benzisoxazoles (Anthraniles) and on the Thermal and Photochemical Decomposition of 2‐Azido‐acylbenzenes in Strongly Acidic SolutionAnthranils 6 (Scheme 3), when irradiated with a mercury high‐pressure lamp, in 96% sulfuric acid yielded, after work‐up, 2‐amino‐5‐hydroxy‐acylbenzenes 8 and as side products 2‐amino‐3‐hydroxy‐acylbenzenes 9 (cf. Schemes 5–7 and Table 1). When C(5) of the anthranils 6 carries a methyl group a more complex reaction mixture is found after irradiation in 96% sulfuric acid (cf. Schemes 8 and 9): 3, 5‐dimethyl‐anthranil (6d) yielded (after irradiation and acetylation) 2‐acetyl‐ amino‐5‐methyl‐acetophenone (15), 2‐acetylamino‐5‐acetoxymethyl‐acetophenone (18d) and 2‐acetylamino‐5‐acetoxy‐6‐methyl‐acetophenone (12c). The latter product was also formed after irradiation of 3, 4‐dimethylanthranil (6c) in 96% sulfuric acid. 3, 5, 7‐Trimethyl‐anthranil (6f) formed under the same conditions 2‐acetylamino‐3, 5‐dimethyl‐acetophenone (15f) and 2‐acetylamino‐5‐acetoxymethyl‐3‐methyl‐acetophenone (18f). Since qualitatively the same product patterns were observed when the corresponding 2‐azido‐acetophenones 7 were decomposed in 96% sulfuric acid it is concluded that anthranilium ions (cf. 6b‐H⊕, Scheme 11) on irradiation are transformed by cleavage of the N, O‐bond into 2‐acyl‐phenylnitrenium ions (cf. 25b‐H⊕) in the singlet ground state. The nitrenium ions are trapped directly by nucleophiles (HSO⊖4 in 96% sulfuric acid), thus, yielding the hydroxy‐acetophenones 8 and 9 (Scheme 11). If C(5) is blocked by a methyl group a [1, 2]‐rearrangement of the methyl group may occur (cf. Scheme 13) or loss of sulfuric acid can lead to quinomethane iminium ions (cf. 32‐H⊕, Scheme 13) which will react with HSO⊖4 ions to yield, after hydrolysis and acetylation, the 5‐acetoxymethyl substituted acetophenones 18d and 18f. It is assumed that the reduction products (2‐acetylamino‐acetophenones 15) are formed from the corresponding nitrenium ions in the triplet ground state.
Photolyse von 3‐Methyl‐2, 1‐benzisoxazol (3‐Methylanthranil) und 2‐Azido‐acetophenon in Gegenwart von Schwefelsäure und Benzolderivaten
Authors: Doppler Thomas , Schmid Hans , Hansen Hans‐Jürgen 
Published: December 2004

Photolysis of 3‐Methyl‐2, 1‐benzisoxazole (3‐Methylanthranil) and 2‐Azido‐acetophenone in the Presence of Sulfuric Acid and Benzene DerivativesIrradiation of 3‐methylanthranil (1) in acetonitrile in the presence of sulfuric acid and benzene, toluene, p‐xylene, mesitylene or anisole with a mercury high‐pressure lamp through a pyrex filter yields beside varying amounts of 2‐amino‐acetophenone (3) and 2‐amino‐5‐hydroxy‐ (4a) and 2‐amino‐3‐hydroxy‐acetophenone (4b) the corresponding diphenylamine derivatives 5 (see Table 1). In the case of toluene and anisole mixtures of the corresponding ortho‐ and para‐substituted isomers (5b, 5d or 5g, 5i respectively), but no meta‐substituted isomers (5c or 5h) are obtained. In addition to these products, the irradiation of 1 in the presence of anisole yields also 2‐amino‐5‐(4′‐methoxyphenyl)‐acetophenone (7), 2‐amino‐3‐(4′‐methoxyphenyl)‐acetophenone (8) and 2‐methoxy‐9‐methyl‐acridine (6; see Scheme 1). The latter product is also formed thermally by acid catalysis from the diphenylamine derivative 5i. Irradiation of 2‐azido‐acetophenone (2) in acetonitrile solution in the presence of sulfuric acid and benzene leads to the formation of 1, 3, 4a, 4b, 5a and 9 (see Table 2). Compounds 3, 4a, 4b and 5a are also obtained after acid catalyzed decomposition of 2 in the presence of benzene. Thus, it is concluded that irradiation of 1 or 2 in the presence of sulfuric acid yields 2‐acetyl‐phenylnitrenium ions 10 in the singlet ground state which will undergo electrophilic substitution of the aromatic compounds, perhaps via the π‐complex 11 (see Scheme 2).