摘要:

AbstractHigh resolution He (Iα) and He (IIα) photoelectron spectra of cubane are reported. The assignments of the bands to different states of the cubane radical cation are made on the basis ofab initioSTO‐3G and MINDO/3 calculations, using geometries optimized within each treatment. The vibrational fine‐structure observed supports the proposed assignment. An open shell MINDO/3 model for ground state cubane radical cation suggests that theJahn‐Tellerdistorted system fluctuates between twelve equivalent structures of C2v‐symmetry. Localized molecular orbitals derived from the STO‐3G model of cubane indicate that the major feature which discriminates this molecule with respect to other hydrocarbons is the large interaction matrix element between the opposed CC‐σ‐orbit

ISSN:0018-019X    

DOI:10.1002/hlca.19780610202

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

AbstractNitric oxide reacts with phenylethylene and arylalkenes under the action of sunlight and at room temperature giving dimeric nitronitroso compounds prouved by IR. spectroscopy (see Table 2) and the corresponding nitroolefins. The main gaseous product is nitrogen as prouved by gaz liquid chromatography (see Table 1). The dimeric nitronitroso compounds can also be obtained by the reaction of dinitrogen trioxide with olefins. The structure of the nitronitroso compounds was further discussed. They may be reduced to give monoamines corresponding to the nitrogroup and may be also converted into nitroolefins.

ISSN:0018-019X    

DOI:10.1002/hlca.19780610203

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Partial Synthesis of (20S)‐ψ‐Vincamine and (20S)‐epi‐16ψVincamineAn attempt of classification of the indole alkaloids is presented; (20S)‐ψ‐vincamine. (20S)‐16‐épi‐ψ‐vincamine and (20S)‐ψ‐apo‐vincamine have been prepared from cat

ISSN:0018-019X    

DOI:10.1002/hlca.19780610204

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

AbstractStarting from the circular dichroism (CD.) of testosterone propionate oriented in a liquid crystal matrix it is shown that the CD., measured with light beams having different directions of propagation with respect to the molecular framework, is different in magnitude and frequency dependence. The vibrational structure is analysed.From the concentration and temperature dependence of the CD. and UV. spectra an order parameter ρ and its concentration and temperature dependence is derived. By this an estimation for the direction of the transition moment of the n → π* transition is gi

ISSN:0018-019X    

DOI:10.1002/hlca.19780610205

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Nitrogen‐containing diiron‐hexacarbonyl complexes from 3‐phenyl‐2H‐azirinesReaction of 2,2‐dimethyl‐3‐phenyl‐2H‐azirine (1) with diiron‐enneacarbonyl yields as an insertion product, and in addition to other products, the diiron‐hexacarbonyl complex2(Scheme 1), whose structure was derived from spectral data, in particular13C‐NMR.‐data (Table 1). With trimethylamine oxide in benzene,2is converted into the urea derivative3, and yields with cerium (IV) ammonium nitrate the nitrate4(Scheme 1). The analogous complexes6and9have been obtained by irradiation of 1‐phenyl‐vinyl azide (5) and ironpentacarbonyl (Scheme 1) and from vinyl isocyanate (8) and diiron‐enneacarbonyl at 40° (Scheme 2), respectively.The azirine1, an acetylenic compound and diiron‐enneacarbonyl in benzene react to give complexes of type10as the main product (Scheme 3). The structure of complex10has been established by X‐ray single crystals analysis. On the13C‐NMR. time scale the carbonyl groups of compound10show a fluxional behaviour: below −50° the CO‐groups of one of the two Fe(CO)3‐groups undergo intranuclear exchange, above −50° the CO‐groups of both Fe(CO)3‐groups undergo intranuclear exchange.Tentative reaction mechanisms for the formation of the compl

ISSN:0018-019X    

DOI:10.1002/hlca.19780610206

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

AbstractHeterocyclic compounds obtained by addition of acetylenedicarboxylic acid esters to thioureas, cyclic amidines ando‐difunctionalized aromatic systems have been studied by13C‐NMR. In particular, C, H‐spin‐coupling constants over two and three bonds were used to differentiate between the various constitutional isomers and to establish the configuration of trisubstituted exocyclic C, C‐double bonds. The configurational significance and diagnostic value of vicinal cis and trans C,H‐spin coupling is again demonstrated in the pre

ISSN:0018-019X    

DOI:10.1002/hlca.19780610207

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Photochemistry of 2‐Alkyl‐indazoles at Low Temperatures2‐Alkyl‐indazoles1undergo a variety of photoreactions (Scheme 1) which have been shown to proceed via excited singlet states of the neutral and protonated indazole, respectively [6]. The quantum yields of these reactions decrease with decreasing temperature; around 150°K the 2‐alkyl‐indazoles are practically reactivity of both neutral and protonated indazoles is observed (Fig. 3), yielding 2‐amino‐acylbenzenes7, obviously formed by hydrolysis of the corresponding imines6(Scheme 2). Yellow ‘intermediates’ (Figs. 1 and 2) which are observable only at low temperatures upon irradiation of neutral indazoles but are rather stable even at room temperature in acid solutions, could be identified as quinoid tautomers8of the imines (Scheme 4). It is assumed that the formation of the imines6proceeds via an arylnitrene or arylnitrenium‐ion13(Scheme 5) and subsequent hydrogen abstraction, the nitrenes being formed directly in their triplet ground‐state from the triple

ISSN:0018-019X    

DOI:10.1002/hlca.19780610208

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

The Photochemistry of Conjugated Epoxy‐enones: Photolysis of 9‐Isopropyl‐6‐methyl‐9,10‐epoxybicyclo [4.4.0]dec‐l‐en‐3‐onThe title compound1undergoes on π, π*‐excitation vinylogous β‐cleavage of the C(γ), O‐bond and isomerizes to the unsaturated 1, 5‐diketone8(58%) and the tricyclic diketone9(14%). On n, π*‐excitation, however,1undergoes only desoxygenation to the dienone7(ca. 15%) besides polymerization. UV.‐irradiation of1(λ ≥ 347 nm) in the presence of tributyl‐stannane gives7in 85% yield; in the presence of tributylstannane‐d11yields13, the deuterated analogon of7(85% yield; d1ca. 50%);7has been proven to be stabl

ISSN:0018-019X    

DOI:10.1002/hlca.19780610209

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

AbstractThe stability constants of the ternary complexes containing UTP, 2,2′‐bipyridyl (bipy), and Co2+, Ni2+, Cu2+, or Zn2+(M2+) have been determined by potentiometric titrations (Table 1). Changes in stability are quantified by Δlog KM= log K M(bipy)(UTP)M(bipy)–log K M(UTP)M. For the Co2+, Ni2+, Cu2+, and Zn2+systems Δlog KMis 0.10, −0.13, 0.36, and 0.15, respectively. All these ternary complexes are considerably more stable than would be expected on statistical grounds; indeed, for Co2+, Cu2+, and Zn2+, UTP4−binds more tightly to M (bipy)2+than to M2+. An UV. difference spectroscopic study suggests that stacked adducts between bipyridyl and the pyrimidine moiety of uridine are formed.1H‐NMR. studies of the bipy/uridine, bipy/UTP, and bipy/UTP/Zn2+systems (Figs. 1 and 2) confirm the presence of stacking in the binary adducts and in the ternary complex. There is also evidence for the existence of the stacked protonated complex, Zn(bipy) (HUTP)−, with the proton at the γ‐phosphate group. The acidity constant of this ternary complex has been measured (Fig. 3). The observed stability enhancement of stacked adducts by the formation of a metal ion bridge is discussed (Fig. 4) and biological impl

ISSN:0018-019X    

DOI:10.1002/hlca.19780610210

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Derivatives of 5,9‐Methano,7,8,9‐tetrahydro‐5H‐benzocycloheptene and Rearrangements to the 1,4‐Ethano‐I,2,3,4‐tetrahydronaphthalene SystemReduction of the oxime2with Raney alloy gives the amine3a, with AlH3a mixture of the isomeric amines3aand3b, whilst LiAlH4yields the aziridines4aand4b. The bicyclo[3.2.1]octane4brearranges under acidic conditions to the bicyclo[2.2.2]octane5. The olefin7can be converted to the aminoalcohol9via the epoxide8and to the amine13using iodine isocyanate: the carbon skeleto. remains intact. However, treatment of the olefin17with iodine isocyanate leads to the bicyclo[2.2.2]octanes21and24in which a skeletal rearrangement has taken place. The configuration was determined by NMR. and X

ISSN:0018-019X    

DOI:10.1002/hlca.19780610211

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY