摘要:

AbstractThis work considers the theoretical aspects of the shift of an alkyl(or aryl) group from a coordinated phosphine to the 16‐electron d8transition metal to which it is coordinated. This rearrangement at first seems to resemble an anionic [1,2]‐sigmatropic shift. But a detailed analysis of the relatively low barrier calculated for the reaction shows how all traces of the forbiddeness of the reaction have vanished. Phenyl migration should eb still more facile. We also analyze in some detail the possible pathways of alkyl halide addition to a phenyl‐Pt complex. An alkyl migration, now from metal to coordinated C‐atom, could possibly intervene in this

ISSN:0018-019X    

DOI:10.1002/hlca.19840670102

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractA new route to the synthesis of the title compound is described.

ISSN:0018-019X    

DOI:10.1002/hlca.19840670103

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

C45‐ and C50‐Carotenoids. Synthesis of Optically Active Acyclic C15‐End GroupsThe optically active C15‐end groups (S)‐12, (S)‐13and (R)‐14were prepared from the C12‐synthon (S)‐11in good chemical and optical yield. These C15‐end groups are suitable compounds for the synthesis of optically active C45

ISSN:0018-019X    

DOI:10.1002/hlca.19840670104

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractA series of 12‐, 14‐, and 16‐membered N2S2‐macrocycles (9–11and19–21) withcisandtrans‐arrangement of the heteroatoms have been synthesized by high‐dilution cyclization and subsequent reduction of the amides with B2H6. With these ligands the corresponding Cu2+‐complexes were prepared and their UV/VIS spectra, their electrochemistry and their EPR properties have been studied. Generally three absorption bands at 270–320 nm, 330–370 nm and 530–620 nm can be observed in aqueous solution and these have been assigned to the N→Cu2+and S→Cu2+charge‐transfer bands and to the d‐d* transition, respectively. The cyclic voltammetry in CH3CN shows in all cases a reversible or quasi‐reversible Cu2+/Cu+‐transition at potentials of 10–480 mV against SHE. The values of g‖and A‖obtained from EPR spectra indicate that the geometry of the Cu2+‐complex of the 14‐memberedcis‐N2S2‐macrocycle i

ISSN:0018-019X    

DOI:10.1002/hlca.19840670105

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractIn the crystal structure of the title compound at 98 K the dimethylamino group has pyramidal geometry. The nitrogenlone pair is not directed towards the triple bond; instead, one NCH3bond lies almost in the plane of the disubstituted ring, directed away from the triple bond, while the other NCH3bond and the lone pair are directed to opposite sides of the plane, nearer to the acetylene. There is a remarkably short intramolecular contact (2.39 Å) between a methyl H‐ and an acetylenic C‐atom. TheTaftσIparameter of the arylethynyl substituent appears to be similar to that of a carboxylic ester, judging from the bond‐angle deformation at the

ISSN:0018-019X    

DOI:10.1002/hlca.19840670106

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractThe He(Iα) photoelectron (PE) spectra of tris(perfluorocyclobuta)benzene4(F)3,3,4,4,7,7,8,8,11,11,12,12‐Dodecafluorotetracyclo[8.2.0.02,5.06,9]dodeca‐1,5,9‐triene, tris(perfluorocyclopenta)benzene5(F)1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9‐Octadecafluoro‐2,3,4,5,6,7,8,9‐octahydro‐1H‐trindene., tetrakis(perfluorocyclobuta)cyclooctatetraene6(F)3,3,4,4,7,7,8,8,11,1l,l2,l2,l5,15,16,16‐Hexadecafluoropentacyclo[12.2.0.02,5.06,9.010,13]hexadeca‐1,5,9,13‐tetraene., and of tetrakis(perfluorocyclopenta)cyclooctatetraene7(F)1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12‐Tetracosafluoro‐1,2,3,4,5,6,7,8,9,10,11,12‐dodeca‐hydrotetracyclopenta[a,c,e,g]cyclooctene.are reported. A tentative assignment of the PE spectra is derived by empirical correlation with those of relevant reference compounds. The results suggest that6(F) retains theD4h‐conformation in the gas phase,i.e. A conformation with a planar cyclooctatetraene ring, as observed in the crystal. All four compounds exhibit a sharp increase of their first ionization energies, relative to the corresponding parent hydrocarb

ISSN:0018-019X    

DOI:10.1002/hlca.19840670107

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

The Heart Glycosides of the Arrow Poison ofLophopetalum toxicumLOHERFrom the cytotoxic and positive inotropic acting bark extract of the PhilippinanLophopetalum toxicumeight heart glycosides have been isolated and their structures have been elucidated mainly by field‐desorption‐MS‐ and1‐ and13C‐NMR spectroscopy. Besides the known k‐Strophanthidin (1), Antiarigenin (6) and β‐Antiarin (Antiarigenin‐3‐β‐O‐α‐L‐rhamnoside,10) the following mono‐ and diglycosides could be identified: strophanthidin‐3‐β‐O‐α‐6‐desoxy‐D‐allopyranoside (strophalloside,2), strophanthidin‐3‐β‐O‐β‐6‐desoxy‐D‐glucopyranoside (= Strophanthidin chinovoside,3), strophanthidin‐3‐β‐O[‐4Oβ‐D‐allopyranosyl‐β‐6‐desoxy‐D‐allopyranoside] (4), strophanthidin‐3‐β‐O‐[3‐O‐β‐D‐glucopyranosyl‐β‐6‐desoxy‐D‐talopyranoside] (5), antiarigenin‐3‐β‐O‐[3‐O‐β‐D‐gulopyranosyl‐β‐6‐desoxy‐D‐talopyranoside] (7), antiarigenin‐3‐β‐O‐[4O‐β‐D‐allopyranosyl‐β‐6‐desoxy

ISSN:0018-019X    

DOI:10.1002/hlca.19840670108

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractThe ligand 2,11‐bis(diphenylphosphinomethyl)benzo[c]phenanthrene (1) has been used to prepare complexes of the type [PtL(1)] (L  C2H4, CH2CHCO2Me, PhCCPh, MeCCMe, MeO2CCCCO2Me, (i‐Pr)O2CCCCO2(i‐Pr), Ph3P and CO). It is shown that these complexes are less labile than the corresponding species [PtL(Ph3P)2]. The preparation of complexestrans‐[PtX(R)(1)] by oxidative addition of RX (RX  PhCH2Br and Mel) to [Pt(C2H4)(1)] is described. The isolation of [PtO2(CH3)2

ISSN:0018-019X    

DOI:10.1002/hlca.19840670109

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

The Acylation of Acetylenes with β,γ‐Unsaturated Acid Chlorides, A New Synthesis of 5‐Substituted 2‐CyclopentenonesThe acylation of acetylenes with α,α‐disubstituted, β,γ‐unsaturated acid chlorides underFriedel‐Crafts‐type conditions leads to 5‐substituted 2‐cyclopentenones. Phenols are formed with β,γ‐unsaturated acid chlorides bearing at least one α‐H‐atom. These transformations are explained by the intramolecular cyclization of the initially formed vinyl cation, which, in the cases of α,α‐disubstituted acid chlorides, is followed by ring contraction. The reaction leading to 2‐cyclopentenones is applied to the synthesis of some spiro[4.4

ISSN:0018-019X    

DOI:10.1002/hlca.19840670110

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractA recent controversy on the interpretation of the ESR spectrum of ionized oxirane is clarified on the basis of the electronic absorption spectra of ionized tetramethyloxirane and 9,10‐octalineoxide. The results favour a ring‐opened structure for oxirane molecular cation, resulting from CC bond cleavage and being iso‐π‐electronic to all

ISSN:0018-019X    

DOI:10.1002/hlca.19840670111

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY