摘要:

AbstractThe naturally occurring Lycopodium alkaloid (+)‐luciduline (1) has been synthesized from (R)‐5‐methyl‐cyclohex‐2‐en‐1‐one (12) by a sequence of seven steps (s.Scheme 6) in 33% overall yield. The key step4→6presumably involves a transient nitrone5which undergoes a highly regioselective intramolecular addition to a non‐pola

ISSN:0018-019X    

DOI:10.1002/hlca.19780610802

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

AbstractThe radical anions of [2.2.2.2]paracyclophane‐ 1,9,17,25‐tetraene (I), [2](2, 5)‐furano [2]paracyclo [2](2,5)furano [2]paracyclophane‐1,8, 16,23‐tetraene (II), [2]‐(2,5)thiopheno [2]paracyclo [2](2,5)thiopheno [2]paracyclophane‐1,8,16,23‐tetraene (III) and [2.2.2.2](2,5)thiophenophane‐1,8,15,22‐tetraene(IV)have been studied by ESR. and ENDOR. spectroscopy. The assignment of the proton coupling constants, aHμis to a large extent based on investigations of deuteriated derivatives. These investigations impressively demonstrate the potential of ENDOR. spectroscopy as an analytical tool. TheArrheniusactivation energies, Ea, for the rotation of phenylene fragments about the bonds linking them with the ethylenic parts inI⊖ andII⊖ are 36±6 and 28±4 kJ/mol, respectively. The value aHμof the olefinic protons in I⊖ appears substantially smaller than expected for the corresponding planar radical anion. The hyperfine data forII⊖,III⊖ andIV⊖ are consistent with the conformations which should minimize the deviations of the macrocyclic π‐systems from planarity. In the case ofII⊖, tight ion pairs are formed by the radical anion and its counter‐ion,K⊕, inDME, owing to the strong association of the alkali metal cation with one of the furan moieties. An analogous interaction ofK⊕ with a thiophene moiety inIII⊖ must be weaker, since no effects of ion pairing on the ESR. and ENDOR. s

ISSN:0018-019X    

DOI:10.1002/hlca.19780610803

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

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 resolvedviadiastereomeric camphanic acid esters. Conversion of the (+)‐enantiomer2via(+)‐5and (+)‐6as 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, (+)‐5and (+)‐6as well as that of (+)‐bicyclo [3.3.1]nonane‐2,6‐dione (1) obtained by oxidation of (+)‐2. T

ISSN:0018-019X    

DOI:10.1002/hlca.19780610804

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

AbstractDye‐sensitized photooxygenations of 3 pairs of (E)/(Z) trisubstituted olefins were studied in order to establish the partitioning between the 3 possible ene additions. The (E)‐isomers underwent only the 2 ene additions (>95%) involving H‐atom abstractions at the same, disubstituted side of the olefins, termedsynene additions, with almost equal ease. The (Z)‐isomers underwent mainly (85‐90%) thesynene additions, with the ones leading to the tertiary hydroperoxides distinctly favoured, and some (10‐15%)ene additions at the monosubstituted side of the olefin, termedantie

ISSN:0018-019X    

DOI:10.1002/hlca.19780610805

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

AbstractResults of crystal structure analyses of seven 1, 8‐disubstituted naphthalenes (2a, 8‐(N,N‐dimethylamino)‐1‐naphthyl methyl ketone;2b, 8‐(N, N‐dimethylamino)naphthalene‐1‐carboxylic acid;2c, methyl 8‐(N, N‐dimethylamino)naphthalene‐1‐carboxylate;2d, 8‐methoxy‐1‐naphthyl methyl ketone;2e, 8‐methoxynaphthalene‐1‐carboxylic acid;2f,N, N‐dimethyl‐8‐methoxynaphthalene 1‐carboxamide;2g,N, N‐dimethyl‐8‐hydroxynaphthalene‐1‐carboxamide) with a nucleophilic centre (N(CH3)2, OCH3, OH) at one of theperipositions and an electrophilic centre (carbonyl C) at the other are described. All seven molecules show a characteristic distortion pattern: the exocyclic bond to the electrophilic centre is splayed outward, and the one to the nucleophilic centre is splayed inward; the carbonyl C is displaced from the plane of its three bonded atoms towards the nucleophile. This distortion pattern differs from that found in other 1,8‐disubstituted naphthalenes and is interpreted as an expression of incipient nucleophilic addition to a carbonyl group. The crystal structure of2bcontains an ordered arrangement

ISSN:0018-019X    

DOI:10.1002/hlca.19780610806

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

AbstractA synthesis of 4, 6‐dimethyl‐2,3,5,7‐tetrathiaoctane (1), from 3,5‐dimethyl‐1,2,4‐trithiolane (6), is described. Compound1, possessing a unique structure was recently found to be a constituent of roaste

ISSN:0018-019X    

DOI:10.1002/hlca.19780610807

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

AbstractThe syntheses of the bis (styryl)benzenes4and5and of the aza analogue3are described. Diamine3and dialdehyde5were cyclized to the 14‐membered macrocycles19and27, respectively. Diamine4and glyoxal give the 28‐membered macrocycle28. The cyclizations are discus

ISSN:0018-019X    

DOI:10.1002/hlca.19780610808

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

AbstractRelative rates of the photoreactions of 1‐(1), 2‐(2) and 4(5)‐valerylimidazole (3) as well as the yields of photo‐fragmentation product10from 1‐(7), 2‐(8) and 4(5)‐stearoylimidazole (9), respectively, were determined. A reaction pathvia NorrishType II fragmentation involving the carbonyl group of 1‐acylimidazole

ISSN:0018-019X    

DOI:10.1002/hlca.19780610809

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

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 product

ISSN:0018-019X    

DOI:10.1002/hlca.19780610810

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

AbstractThe irradiation of 1‐(dehydroabietoyl) imidazole(3)gave no Type II elimination product but yielded instead compounds6and7by migration of the imidazolylcarbonyl group from C(4′) to C(6′) of the abietan moiety, probably via a cyclobutanol intermediate. Similarly, irradiation of 1‐(13′‐deisopropyl‐10′‐epi‐dehydro‐abietoyl)imidazole(13)gave only a small amount of Type II fragmentation product20, the main products derived from γ‐hydrogen abstraction being the cyclobu

ISSN:0018-019X    

DOI:10.1002/hlca.19780610811

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY