摘要:

AbstractPentadienyllithium(16)was regioselectively and efficiently transformed to 1‐trimethylsilyl‐2,4‐pentadiene(17)by reaction with chlorotrimethylsilane (Scheme 5). Deprotonation of17and subsequent electrophilic attack furnished the regioisomeric products12and/or13in good yields (Schemes 5and6). The utility of the reaction18→12for the convergent assembly of the 1‐silyl‐1,3‐butadiene unit with an olefinic dienophile is further illustrated by the smooth intramolecularDiels‐Ald

ISSN:0018-019X    

DOI:10.1002/hlca.19800630302

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

Note on the Synthesis of (E)‐12‐Hydroxy‐10‐heptadecenoic Acid, (5E, 10E)‐12‐Hydroxy‐5, 10‐heptadienoic Acid and (5Z, 10E)‐12‐Hydroxy‐5,10‐heptadienoic AcidThe syntheses of two heptadecadienoic and one heptadecenoic acid, compounds which formally may be derived from prostaglandin‐like molecules by removal of a C3‐fragment from the five

ISSN:0018-019X    

DOI:10.1002/hlca.19800630303

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

AbstractThe photoelectron spectrum of the title compound is reported and assigned by correlation with the photoelectron spectra of related molecules.

ISSN:0018-019X    

DOI:10.1002/hlca.19800630304

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

The Photochemistry of Open‐Chained 2,6‐ or 2,7‐Dien‐Carbonyl CompoundsOn1n, π*‐excitation (λ>347 nm) citral(5)and the methyl ketone10isomerize to compoundsA (7, 19)andB (6, 20), whereas the phenyl ketone11changes into the isomer24of typeE.Evidence is given that the conversions toAandBmay arise from the3n, π*‐state of the 2,6‐diene‐carbonyl compounds.On1n, π*‐excitation (λ = 254 nm)5and10yield the isomersA (7, 19)andD (18, 22), but no products of typeB.Furthermore, conversion of10to the isomer21of typeCis observed.Selective1n, π*‐excitation (λ = 254 nm) as well as selective1n, π*‐excitation (λ>347 nm) of the 2,7‐diene‐carbonyl compounds12and13give rise to isomerization to the compoundsF (25, 28), exclusively. The intramolecular [2 + 2]‐photocycloadditions are shown to be triplet processes.UV.‐irradiation (λ>280 nm) of compoundsF (25, 28)furnishes the isomeric productsG (26, 29)which photo

ISSN:0018-019X    

DOI:10.1002/hlca.19800630305

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

AbstractContrary to the findings in the photolysis ofN‐acylimidazoles [2] irradiation of 1‐acyl‐1,2,4‐triazoles afforded no photo‐Friesproduct, but instead products formedviathe corresponding acyl radicals and aldehydes. Photolysis of 2‐acyltetrazoles gave in part the same products as those obtained from the irradiation of the corresponding acyl‐triazoles as well as 2‐alkyl‐1,3,4‐oxadiazoles.N‐Acyltetrazoles didn't give any photo

ISSN:0018-019X    

DOI:10.1002/hlca.19800630306

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

AbstractFour triterpenoid saponins(1–4)have been isolated from the berries ofHedera helixL.(Araliaceae)by droplet counter‐current and preparative liquid chromatography. The structures have been established by FD./MS. and13C‐NMR. spectroscopy. The isolated compounds were found to possess strong molluscicidal activity against the bilharziasis‐transmitting snailBiomphalaria glabrata.Saponin4, identified as hederagenin 3‐O‐β‐D‐glucopyranosyl‐(1 → 2)‐β‐D‐glucopyranosid

ISSN:0018-019X    

DOI:10.1002/hlca.19800630307

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

Detection of Fragment Genesis in the Mass Spectrometer. V. Amino Acid Sequence Analysis by DADI/MIKE, Linked Scan and Collisional Activation Mass Spectrometry. Aliphatic Amino AcidsThe amino acid sequence in tripeptides and tetrapeptides has been analyzed by DADI/MIKE and B/E‐‘linked scan’ spectrometry, as well as by collisional activation in the first and second field free region of a mass spectrometer embodying the inverseNier‐Johnsongeometry. Collisional activation enhances the intensity of fragme

ISSN:0018-019X    

DOI:10.1002/hlca.19800630308

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

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 mo

ISSN:0018-019X    

DOI:10.1002/hlca.19800630309

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

Syntheses and Pharmacological Properties of 2,2‐Dialkyl‐5‐aryl‐3‐pyridylpyrrolidinesReaction of the photochemically generated benzonitrile methylides2with vinylpyridines yields 2‐aryl‐4‐pyridyl‐1‐pyrrolines3.Depending on reduction methods, the compounds3are selectively transformed to the correspondingcis‐ or thetrans‐substituted pyrrolidines10or11, respectively. Furthermore, a non‐photochemical synthesis has been developed: the easily available nitro‐ketones8provide through reductive cyclization the pyrrolines3or directly the pyrrolidines11.Twenty‐seven compounds of types10and11have been evaluated in the writhing, hot plate and kaolin tests; especially thecis‐pyrrolidines10exhibit a valuable antinociceptive activity. Some of the pyrrolines and pyrrolidines have been separated into their enantiomers,

ISSN:0018-019X    

DOI:10.1002/hlca.19800630310

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

Synthesis and Photochemistry of 3‐(2‐Thienyl)‐2,2‐dimethyl‐2H‐azirineThe synthesis of 3‐(2‐thienyl)‐2,2‐dimethyl‐2H‐azirine(1)is described. UV. irradiation of1in benzene solution generates the nitrile isopropylide2which 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 of2to the C,

ISSN:0018-019X    

DOI:10.1002/hlca.19800630311

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY