bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ionophore extrem hoher Lipophilie als selektive Komponenten für Flüssigmembranelektroden
Authors: Oesch Urs , Ammann Daniel , Pretsch Ernö , Simon Wilhelm 
Published: December 2004

Selective ionophores of extreme lipophilicity for liquid membrane electrodesLipophilic ionophores of the type diether diamides have been prepared. Their lipophilicity is up to 7 orders of magnitude higher than the one of the most lipophilic ion carriers used as selective components in liquid membrane electrodes reported so far. For such ion carriers of extremely high lipophilicity kinetic limitations of the carrier induced ion transfer between aqueous and membrane phase usually dominate and heavily disturb the electromotive behavior of the membrane electrode. These limitations are absent only in those cases where most of the lipophilic segments of the carrier may remain in the membrane phase while the segments with the coordination sites are exposed to the aqueous phase during the transfer process.
195Pt‐NMR. Spectroscopy. The direct measurement of the values 1J (195Pt, 14N) and chemical shift data for the complexes trans‐[PtCl2(C2H4) (substituted pyridine)]
Authors: Motschi Herbert , Sze Siu N. , Pregosin Paul S. 
Published: December 2004

AbstractThe values nJ (195Pt, 14N) are shown to be measurable directly from the 195Pt spectrum for a variety of complexes containing nitrogen ligands. The sample temperature can play an important role in determining the width of the 195Pt signal. 195Pt chemical shifts for the complexes trans‐[PtCl2(C2H4) (substituted pyridine)] have been measured. Methyl substitution at the 2‐ and 6‐positions produces a relatively large downfield shift.
Transition Metal Complexes with Bidentate Ligands Spanning trans‐Positions. VII. The preparation of the five‐coordinate complexes [M(CO)3(1)] (M = Fe, Ru; (1) = 2,11‐bis(diphenylphosphinomethyl)benzo[c]phenanthrene)
Authors: Holderegger Rolf , Venanzi Luigi M. 
Published: December 2004

AbstractThe five‐coordinate mononuclear complexes [M(CO)3(1)] (M = Fe, Ru; (1) = 2,11‐bis(diphenylphosphinomethyl)benzo[c]phenanthrene) have been prepared and assigned trigonal bipyramidal structures with apical phosphorus atoms from IR. and NMR. data.
Synthesis of (R)‐ and (S)‐p‐Mentha‐1,8‐dien‐4‐ols from (R)‐Limonene
Authors: Delay François , Ohloff Günther 
Published: December 2004

AbstractSynthesis of both enantiomers of p‐mentha‐1,8‐dien‐4‐ol (1) from commercially available (+)‐(R)‐limonene (2) is described.
Anwendung der «Zip»‐Reaktion zur Synthese eines 53gliedrigen Polyaminolactams. 8. Mitteilung über Umamidirungsreaktionen
Authors: Kramer Urs , Guggisberg Armin , Hesse Manfred 
Published: December 2004

Use of the ‘Zip’ reaction for the synthesis of a 53‐membered polyminolactamThe synthesis of N‐(39‐amino‐4, 8, 12, 16, 20, 24, 28, 32, 36‐nonaaza‐nonatriacontyl)‐12‐dodecanlactam (1)In ‘5’ wurden die Verbindungen 1 als 1‐(39‐Amino‐4,8,12,16,20,24,28,32,36‐nonaazanonatriacontyl)‐1‐azacyclotridecan‐2‐on, 4 als 7‐Chlor‐1‐phthalimido‐4‐tosyl‐4‐azaheptan, 5 als 7‐Jod‐1‐phthalimido‐4‐tosyl‐4‐azaheptan und 20 als 1,5,9,13,17,21,25,29,33,37,41‐Undecaazatripentacontan‐42‐on bezeichnet.

has been described. The formation of synthon
2
, used for the chain extension of the known
12
[6] shown in
Scheme 2
, is demonstrated in
Scheme 1
. In presence of base (KAPA‐reagent),
1
undergoes the so called ‘Zip’‐reaction resulting in a ring‐expansion by 40 members which leads to
20
.
The Reaction of Cyclopropyl Ketones with Acetyl Methanesulfonate. An efficient ring opening under neutral conditions with regiospecific enol acetate formation and stereo‐controlled nucleophilic addition. Preliminary communication
Authors: Demuth Martin , Raghavan Palaykotai R. 
Published: December 2004

AbstractCyclopropyl ketones are readily cleaved under neutral conditions at room temperature by the combined action of acetyl methanesulfonate and nucleophiles such as Br−, I−, and MsO−. The high‐yield reaction involves regiospecific enol acetate formation with a stereoselectivity of nucleophile addition which is compatible with an SN2‐type opening of the cyclopropyl ring.
Strukturen von 13 Diterpenen (Coleonen) aus Blattdrüsen von Solenostemon sylvaticus und Coleus garckeanus (Labiatae)
Authors: Miyase Toshio , Yoshizaki Fumihiko , Kabengele N'Tanda , Rüedi Peter , Eugster Conrad Hans 
Published: December 2004

Leaf‐gland pigments from labiatae: structures of 13 diterpenoids (coleons) from Solenostemon sylvaticus (GÜRKE) T.T. AYE and Coleus garckeanus VATKEThe above mentioned East‐African labiatae have been investigated for their leaf‐gland pigments. The two plants contain very similar abietanoic diterpenoids. Besides the already known coleons O (5a) and W (1a), 11 novel compounds have been isolated and their structures established:Diosphenol: 16(or 17)‐O‐acetyl‐coleon W (1b).Diketones: Coleon X (16 or 17)‐acetoxy‐11, 12, 14, 17 (or 16)‐tetrahydroxy‐abieta‐8, 11, 13‐triene‐6,7‐dione (2a); 16 (or 17)‐O‐acetyl‐coleon X (2b).Spiro‐coleons: 6‐O‐acetyl‐19‐acetyloxy‐coleon Q (3b); 12‐O‐desacetyl‐7‐O‐acetyl‐19‐acetyloxy‐coleon Q (3c); 12‐O‐desacetyl‐7‐O‐acetyl‐19‐acetyloxy‐coleon P (3e); 12‐O‐desacetyl‐7‐O‐acetyl‐3β, 19‐diacetyloxy‐coleon Q (4b); 19‐acetyloxy‐coleon O (5b); 12‐O‐desacetyl‐6‐O‐acetyl‐17‐acetyloxy‐coleon P (7); 7‐desoxy‐12‐O‐desacetyl‐3‐acetyloxy‐coleon N (6b); coleon Z (8).Compound 7 contains a spiro cycloprope unit, substituted by one carbonyl and two carbinol functions. Compound 8 (Coleon Z) contains a unique cis‐butadiene unit formed from C(3)–C(4)–C(18)–C(19).
Totalsynthese von natürlichem α‐Tocopherol. 4. Mitteilung. Aufbau des Chromanringsystems aus Trimethylhydrochinon und einem optisch aktiven C4‐ bzw. C5‐Synthon
Authors: Barner Richard , Schmid Max 
Published: December 2004

Total Synthesis of Natural α‐TocopherolTwo independent syntheses of (S)‐6‐hydroxy‐2,5,7,8‐tetramethylchroman‐2‐yl‐methanol (8b), (Scheme 6 resp. 9) as optically active chroman moiety for the preparation of natural vitamin E via (S)‐6‐acetoxy‐2,5,7,8‐tetramethylchroman‐2‐carboaldehyde (2a) (Scheme 1) and a corresponding side chain are described. Both reaction sequences use trimethyl‐hydroquinone as starting material; one approach employs an optically active C4 unit (10a) (Schemes 5 and 6) to introduce the required configuration at C(2), the other uses an optically active C5‐synthon (11a) (Schemes 8 and 9) to build the optically active chroman unit. The correct configuration and optical purity of the chroman synthesized is established by correlation with optically pure material of known configuration from which natural vitamin E had already been derived [2].
Carbocyclische Verbindungen aus Monosacchariden. II. Umsetzungen in der Mannosereihe
Authors: Bernet Bruno , Vasella Andrea 
Published: December 2004

Carbocyclic compounds from monosaccharides. II. Transformations in the mannose seriesUpon treatment with Zn in refluxing aqeous ethanol or butanol, the anomeric mannopyranosides 11 and 14 yielded the aldehyde 15 which was subjected (via its N‐methyl‐nitrone) to an intramolecular nitrone‐olefine cycloaddition leading diastereoselectively to 18 in a yield of 64% from 14. Minor products of this reaction sequence were the compounds 19, 20 and 21. Similarily, the easily accessible unsaturated furanose 26, upon treatment with N‐methyl‐hydroxylamine gave the isoxazolidines 27 (84%) and 28 (3%), thus showing that a free 4‐hydroxy group is not detrimental to this intramolecular nitrone‐olefin cycloaddition. The configuration of 18, 27 and 28 (resp. 29) were determined by spectroscopic means; that of 27 was further proven by transformation into the compound 31, of which an X‐ray analysis was performed.
Defense Allomones of the Nudibranch Phyllidia varicosa Lamarck 1801
Authors: Hagadone Mark R. , Burreson B. Jay , Scheuer Paul J. , Finer Janet S. , Clardy Jon 
Published: December 2004

AbstractThe defensive secretion of the nudibranch Phyllidia varicosa consists of two isocyanosesquiterpenes: the previously described 9‐isocyanopupukeanane (1), and its 2‐isomer (4), for which we report the structure and properties. The mixture originates with a sponge, Hymeniacidon sp., where it is produced in varying proportions. CD. measurements and X‐ray diffraction data establish the absolute configuration of the two metabolites.
Bestrahlung von 4‐allylierten 2,6‐Dimethylanilinen in Methanol
Authors: Bader Heinz , Hansen Hans‐JüRgen 
Published: December 2004

Irradiation of 4‐Allylated 2,6‐Dimethylanilines in Methanol4‐Allyl‐, 4‐(1′‐methylallyl)‐, 4‐(2′‐butenyl)‐, and 4‐(1′,1′‐dimethylallyl)‐2,6‐dimethylaniline (14–17; cf. Scheme 3) were obtained by the acid catalysed, thermal rearrangement of the corresponding N‐allylated anilines in good yields. Aniline 14, when irradiated with a high pressure mercury lamp through quartz in methanol, yielded as main product 4‐(2′‐methoxypropyl)‐2,6‐dimethylaniline (22; cf. Scheme 4) and, in addition, 2,6‐dimethyl‐4‐propylaniline (18) and 4‐cyclopropyl‐2,6‐dimethylaniline (23). The analogous products, namely erythro‐ and threo‐4‐(2′‐methoxy‐1′‐methylpropyl)‐2,6‐dimethylaniline (erythro‐ and threo‐24), 2,6‐dimethyl‐4‐(1′‐methylpropyl)aniline (19), trans‐ and cis‐2,6‐dimethyl‐4‐(2′‐methylcyclopropyl)aniline (trans‐ and cis‐25), as well as small amounts of 4‐ethyl‐2,6‐dimethylaniline (26), were formed by irradiation of 15 in methanol (cf. Scheme 5). When this photoreaction was carried out in O‐deuteriomethanol, erythro‐ and threo‐24 showed an up‐take of one deuterium atom in the side chain. The mass spectra of erythro‐ and threo‐24 revealed that in 50% of the molecules the deuterium was located at the methyl group at C(1′) and in the other 50% at the methyl group at C(2′) (cf. Scheme 6). This is a good indication that the methanol addition products arise from methanolysis of intermediate spiro[2.5]octa‐4,7‐dien‐6‐imines (cf. Scheme 7). This assumption is further supported by the photoreaction of 17 in methanol (cf. Scheme 8) which led to the formation of 4‐(2′‐methoxy‐1′,2′‐dimethylpropyl)‐2,6‐dimethylaniline (28) as main product. The occurrence of a rearranged side chain in 28 can again be explained by the intervention of a spirodienimine 31 (cf. Scheme 9). In comparison with 14, 15 and 17, the 2′‐butenylaniline 16 reacted only sluggishly on irradiation in methanol (cf. Scheme 10). It is suggested that all photoproducts ‐ except for the cyclopropyl derivatives which are formed presumably via a triplet di‐π‐methane rearrangement ‐ arise from an intramolecular singlet electron‐donor‐acceptor complex between the aniline and ethylene chromophor of the side chain. Protonation of this complex at C(3′) or C(2′) will lead to diradicals (e.g. 33 and 34, respectively, in Scheme 11). The diradicals of type 33 undergo ring closure to the corresponding spirodienimine intermediates (e.g. 31) whereas the diradicals of type 34 take up two hydrogen atoms to yield the photo‐hydrogenated compounds (e.g. 21) or undergo to a minor extent fragmentation to side chain degraded products (e.g. 30; see also footnote 7).–Irradiation of 4‐ally‐2,6‐dimethylaniline (14) in benzene or cyclohexane yielded the corresponding azo compound 38 (cf. Scheme 12), whereas its N,N‐dimethyl derivative 41 was transformed into the cyclopropyl derivative 42. The allyl moiety in 14 is not necessary for the formation of azo compounds since 2,4,6‐trimethylaniline (39) exhibited the same type of photoreaction in benzene solution.
Macrocyclic Ring Closure of OH‐assisted Prins Reaction. A new and efficient synthesis of (R,S)‐muscone
Authors: Schulte‐Elte Karl H. , Hauser Arnold , Ohloff Günther 
Published: December 2004

AbstractA new strategy for the synthesis of muscone (1) using the OH‐assisted Prins reaction for macrocyclic ring closure has been developed. The monoacetal 4 of (Z,E)‐4,8‐dodecadienedial (3), easily obtainable from (Z,E,E)‐1,5,9‐cyclododecatriene (2), is treated with methallylmagnesium chloride, and the resulting C16‐precursor 5 is subjected to acid‐catalyzed cyclization in dilute (⩽1%) solutions. This results in formation of the bicyclic dihydropyran derivatives 6 which directly yield muscone (1) on heating with a noble metal catalyst saturated with hydrogen. The five‐step pathway proceeds with readily available starting materials in conventional steps and excellent overall yield (∼40%). This new principle of macrocyclic ring formation has also been used successfully for the preparation of 3‐methylcyclotridecanone (34) and should be generally applicable for other suitable ring systems.
Three New Chiral Aminoethers from Tartaric Acid for Improved Asymmetric Syntheses with Organolithium Reactions. Preliminary communication
Authors: Seebach Dieter , Crass Gerhard , Wilka Eva‐Maria , Hilvert Don , Brunner Edi 
Published: December 2004

AbstractThe chiral aminoethers 1–4, accessible from tartaric acid, are tested as complexing ligands in organolithium reactions. The tetramine 4 turns out to cause highest inductions [see Table 2 and Equations (1)–(4)].
Über die Stereospezifität der α‐Alkylierung von β‐Hydroxycarbonsäureestern. Vorläufige Mitteilung
Authors: Fráter György 
Published: December 2004

About the Stereospecific α‐Alkylation of β‐HydroxyestersIt was found, that dianions derived from β‐hydroxyesters with lithium diisopropylamide (LDA) at −50 to −20° were alkylated stereospecifically (Scheme 1). The stereospecificity was 95–98%, the threo‐compound (threo‐2, ‐3 and ‐4) being the main product. This was proved for threo‐2 and ‐3 by preparing the β‐lactones 7 and 8, respectively, which were pyrolyzed to trans‐1, 4‐hexadiene (9) and trans‐1‐phenyl‐2‐butene (10), respectively (Scheme 2). Moreover, the acid threo‐6 from threo‐3 was converted by dimethylformamide‐dimethylacetal to cis‐1‐phenyl‐2‐butene (11) (s. footnote 6).The alkylation of α‐monosubstituted β‐hydroxyesters also turned out to be stereospecific. Reduction of 16 and 18 with actively fermenting yeast furnished (+)‐17 and (+)‐2. respectively (Scheme 4), which were each mixtures of the (2R, 3S)‐ and the (2S, 3S)‐isomers. Alkylation of (+)‐17 with allyl bromide yielded after chromatography (2S, 3S)‐19 and of (+)‐2 with methyl iodide (2R, 3S)‐19, the oxidation of which finally gave (S)‐(−)‐20 and (R)‐(+)‐20, respectively.
Aktivierte Chinone: regiospezifische Synthesen von substituierten Dibenzo [b, d]pyran‐6‐onen und Benzo [b]naphtho [d]pyran‐6‐onen
Authors: Müller Peter , Venakis Thomas , Eugster Conrad Hans 
Published: December 2004

Activated Quinones: Regiospecific Syntheses of Substituted Dibenzo [b, d]pyran‐6‐ones and Benzo[b]naphtho [d]pyran‐6‐onesThe reaction of 2‐methoxycarbonyl‐1, 4‐benzoquinone (1) with substituted phenols leads in an acid‐catalyzed, regiospecific way to substituted dibenzo [b, d]‐pyran‐6‐ones (compounds 3 and 6). The cycloaddition of 1,3‐butadiene to the latter yields compounds 7. Tautomerisation of 7 and oxidation gives the benzo[b]‐naphtho[d]pyran‐6‐ones 8 and 10, respectively.
Oxydations et halogénations régiosélectives et réactions carbéniques de dérivés de sucres portant un groupement thioéther
Authors: Tronchet Jean M. J. , Eder Hansjörg 
Published: December 2004

Regioselective Oxidations, Regioselective Halogenations and Carbene Reactions of Sugar Derivatives Bearing a Thioether GroupRegioselective stoechiometrically controlled procedures are described for the oxidation of thiosugars either at the sulfur atom (to sulfoxides or sulfones) or at a hydroxymethylene group (to ketosugars). Ruthenium tetraoxide reacted at both sites. Chloration (SO2Cl2) of β‐ketothioether sugar derivative 3 took place exclusively at C(6). Evidence is given that a chlorosulfonium intermediate C was formed when the dichloroketothiosugar derivative 6 was treated with SO2Cl2. The carbene generated from the tosylhydrazone 16 rearranged to the enoses 17–20, the migrating group coming in equal proportions from C(4) and C(6). Some stereochemical aspects of these reactions are discussed.
A Class of Trinuclear Clusters with Carbonyl Bridging
Authors: Pinhas Allan R. , Albright Thomas A. , Hofmann Peter , Hoffmann Roald 
Published: December 2004

AbstractThe impetus for this work was the structure of a trinuclear complex with two carbonyl groups showing incipient triple bridging ‐ Cp2Rh3(CO)4−. Its structure, barrier to rotation of one Rh(CO)2− piece vs. the rest of the molecule, and the nature of the bridging carbonyl interaction are analyzed. Isolobal analogies form an interesting connection between this complex and a bridged isomer of the recently synthesized carbene complexes, Cp2Rh2(CO)2CR2, one isomer of Cp2Rh3(CO)3, and hypothetical carbyne complexes Cp2Rh2(CO)2CH+,−. A general bonding model for Cp2Rh2(μ‐CO)2X complexes is constructed. The model, rich in geometrical detail, allows minima for the bridging carbonyl groups bending toward and away from the bonded ligand X.
Stereochemistry‐Activity Relationships in Olfaction. Odorants containing a proton donor/proton acceptor unit
Authors: Ohloff Günther , Giersch Wolfgang 
Published: December 2004

AbstractA novel class of odorants is described where the odor is associated with the interaction of two functional groups, one being an H‐donor (AH function), and the other an H‐acceptor (B function). Generally, odor occurs only if the distance between the two structural elements (AH/B system) is less than 3 Å. Bifunctional derivatives of the p‐menthane and iridane series served as models for deriving this rule. The stereospecificity of odor perception was an important prerequisite for its establishment.
Drüsenfarbstoffe aus Labiaten: Ecklonochinone A und B, zwei neuartige Dibenzo‐p‐dioxin‐o‐chinone aus Plectranthus ecklonii BENTH
Authors: Uchida Masaaki , Rüedi Peter , Eugster Conrad Hans 
Published: December 2004

Leaf‐gland Pigments from Labiatae: Ecklonoquinones A and B, Two Novel Dibenzo‐p‐dioxine‐o‐quinones from Plectranthus ecklonii BENTHFrom the leaf‐glands of the above mentioned labiate the following compounds have been isolated and their structures established: ecklonoquinone A (1) and ecklonoquinone B (2), two novel isomeric dibenzo‐p‐dioxine‐orthoquinones; 2 (S)‐5,4′‐dihydroxy‐6,7‐dimethoxyflavanone (8); the already known flavone cirsimaritin (9) and the diterpenoid p‐quinomethane parvifloron F (10a). The spectral data of the dimeric p‐menthanes 1 and 2 are very similar, and only analysis of the 1H‐coupled 13C‐NMR.‐spectra lead to structures 1 and 2, respectively. Our tentative assignment of these structures to the individual molecules is based on a comparison of the spectral data with the synthetic compound 7.
Stoffwechselprodukte von Mikroorganismen. 190. Mitteilung. Über das 4‐Oxo‐homotyrosin, ein Abbauprodukt des Echinocandins B
Authors: Keller‐Schierlein Walter , Joos Beda 
Published: December 2004

AbstractD, L‐4‐Oxo‐homotyrosine was synthesized by the acetylaminomalonic ester pathway. The optical resolution was carried out by means of the enzyme acylase I. The L‐configuration of the enzymatically produced amino acid was confirmed by degradation to L‐aspartic acid.4‐Oxo‐homotyrosine obtained by degradation of the polypeptide antibiotic echinocandine B has D‐configuration, but his optical purity is low. A hypothetical explanation for its formation from the (2 S, 3 S, 4 S)‐3,4‐dihydroxyhomotyrosine residue of echinocandine B is proposed.
Synthesis and Configuration of the Eight Diastereoisomeric Racemates of Dactyloxene‐B. The relative configuration of dactyloxene‐B and ‐C
Authors: Maurer Bruno , Hauser Arnold , Thommen Walter , Schulte‐Elte Karl H. , Ohloff Günther 
Published: December 2004

AbstractThe eight possible diastereoisomeric racemates of dactyloxene‐B have been synthesized by a non‐stereoselective route and their configurations and predominant conformations determined by 360‐MHz‐1H‐NMR. and 90.5‐MHz‐13C‐NMR. spectroscopy. Natural dactyloxene‐B and ‐C are shown to have the relative configuration rel‐(2R, 5R, 9S, 10R) and rel‐(2R, 5S, 9S, 10R), respectively.
Papain Catalyzed Oligomerization of α‐Amino Acids. Synthesis and characterization of water‐insoluble oligomers of L‐methionine
Authors: Jost Rolf , Brambilla Edgardo , Monti Julio C. , Luisi Pier Luigi 
Published: December 2004

AbstractWater‐insoluble oligomers were synthesized from L‐methionine ethyl ester with papain as the catalyst. L‐Oligomethionine was obtained in yields of 50% when synthesis was carried out in highly concentrated citrate buffer at pH 5.5. Yields of up to 85% were obtained when the enzymatic synthesis proceeded in distilled water at pH 6.5, the pH being strictly maintained. The insoluble polymer was converted to highly water‐soluble sulfoxide and sulfone derivatives, which consist mainly of an octamer with low amounts of heptamer or hexamer. Most of the carboxyl terminals still contained the ethyl ester group, only a minor part being present in the free acid form. The potential of the enzymatic approach for the synthesis of optically pure and monodisperse oligomers of α‐amino acids is discussed.
Transition‐Metal Complexes with Bidentate Ligands Spanning trans‐Positions. IX. Preparation and 1H‐NMR. Studies of complexes [MX2(1)] and [M′Cl(CO)(1)] (M = Pd, Pt; M′ = Rh, Ir; X = Cl, Br, I; 1 = 2, 11‐Bis‐(diphenylarsinomethyl)benzo[c]phenanthrene) and crystal and molecular structure of [PtCl2(1)]
Authors: Balimann Giovanni , Venanzi Luigi M. , Bachechi Fiorella , Zambonelli Luigi 
Published: December 2004

AbstractThe preparation of the bidentate ligand 2, 11‐bis(diphenylarsinomethyl)benzo‐[c]‐phenanthrene (1) is described. This ligand reacts with appropriate substrates to give mononuclear square planar complexes of type [MX2(1)] (M = Pd, Pt; X = Cl, Br, I) and [M′Cl(CO)(1)] (M′ = Rh, Ir) in which ligand 1 spans trans‐positions. This is confirmed by the crystal structure of [PtCl2(1)]. 1H‐NMR. spectra of the complexes are discussed and compared with those of model compounds trans‐[MCl2(12)2] (M = Pd, Pt) and [M'Cl(CO)(12)2] (M′ = Rh, Ir; 12 = AsBzPh2).
Radical Cation States of 2,3,5,6,7,8‐Hexamethylidenebicyclo [2.2.2]octane
Authors: Mohraz Manijeh , Jian‐qi Wang , Heilbronner Edgar , Vogel Pierre , Pilet Olivier 
Published: December 2004

AbstractThe photoelectron spectrum of the title compound is reported and assigned by correlation with the photoelectron spectra of related molecules.
Computation of the ESR. Coupling Constants of the [16]Annulene Radical Anion; Theoretical and Experimental Reinvestigation of the Excited States of [16]Annulene and its Mono‐ and Dinegative Ions
Authors: Baumann Harold , Oth Jean F. M. 
Published: December 2004

AbstractThe problem of assigning the two small ESR. coupling constants of the [16]annulene radical anion to the two sets of four equivalent outer and inner ring protons is treated by three different semiempirical MO methods. All three methods indicate that the smaller coupling constant (0.743 Gauss) should be assigned to the inner protons, and the larger one (0.963 Gauss) to the outer ones. The electronic spectra of [16]annulene, its radical anion, and its dianion have been remeasured. Especially interesting was the detection of a symmetry‐forbidden band of the radical anion at 1473 nm (6789 cm−1, logε 2.57). The spectra are discussed in terms of different MO models.
Photoreaktionen des 3‐(2‐Thienyl)‐2,2‐dimethyl‐2H‐azirins
Authors: Pfoertner Karl‐Heinz , Zell Reinhard 
Published: December 2004

Synthesis and Photochemistry of 3‐(2‐Thienyl)‐2,2‐dimethyl‐2H‐azirineThe synthesis of 3‐(2‐thienyl)‐2,2‐dimethyl‐2 H‐azirine (1) is described. UV. irradiation of 1 in benzene solution generates the nitrile isopropylide 2 which reacts in a regiospecific manner with activated C, C and C, O double bonds to give 1‐pyrrolines and 3‐oxazolines, respectively. With chelidonic acid diethyl ester the cycloaddition of 2 to the C, C double bond is preferred.