摘要:

AbstractThe reaction of allyl cations and 1,3‐dienes affords seven‐, five‐, and six ‐membered rings as well as products of electrophilic substitution and linear 1:1‐adducts. In this review article, preparative and mechanistic advances are summarized with special emphasis on the synthesis of seven‐membered carbocycles. For the first time, a comprehensive mechanistic description is presented: Three classes A, B, and C correlate product type and stereochemistry with the nucleophilicity of the diene, the electrophilicity of the allyl cation intermediate, and the donor capacity of the group Y attached to the central carbon of the allylic moiety. The problem “allylic resonance versus nucleophilic participation of Y” is discussed and experimental evidence is adduced for some participation of Y as a function of its nucleophilicity. For cyclopentenyl cations, enhanced charge separation and electrophilicity are postulated, even when Y is a good donor, due to the structurally enforced polarity of the

ISSN:0570-0833    

DOI:10.1002/anie.198400013

出版商:Hüthig&Wepf Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractCarbocations are intrinsically reactive species, and in early studies of their generation and properties the more accessible with stabilizing influences were naturally the prime objects of interest. Now, however, it is possible to extend the scope of these studies to include factors which tend to destabilize carbocations. By using the carbocations CH 3⊕and C2H 5⊕as reference ions, such destabilizing factors can be defined; these include various structural factors, antiaromaticity effects, and the presence of electron‐withdrawing substituents. Such factors can be studied by their effect on the thermodynamics of carbocations, their effect on reactivities, and by the spectroscopic properties of long‐lived carbocations. Destabilized carbocations of this type are receiving increasing attention and promise to remain an active subject of in

ISSN:0570-0833    

DOI:10.1002/anie.198400201

出版商:Hüthig&Wepf Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractNodal nomenclature is compared with classical organic nomenclature, and the procedure by which an organic compound is given a nodal name is described. Parent hydride–especially hydrocarbon–names are derived from the names of structure graphs and are modified to incorporate descriptions of heteroatoms, unsaturation, free valences, and ionic charges. It is also shown how the substitutive method, though not an integral part of the nodal system, may nevertheless be used as a way to simplify the structure graphs without impairing the logic of the nodal system. For this purpose, it is indicated how to use prefixes or suffixes generally formed according to IUPAC Rules. The rôle of substitution in organic nodal nomenclature is more restricted than in classical nomenclature because many classical substituents are treated as part of the parent hydrides. The concept of “characteristic group” is not used in nodal nomenclature for similar reasons, and the term “principal substituent” is preferred to “principal charact

ISSN:0570-0833    

DOI:10.1002/anie.198400331

出版商:Hüthig&Wepf Verlag    

年代:1984

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198400532

出版商:Hüthig&Wepf Verlag    

年代:1984

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198400541

出版商:Hüthig&Wepf Verlag    

年代:1984

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198400551

出版商:Hüthig&Wepf Verlag    

年代:1984

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198400571

出版商:Hüthig&Wepf Verlag    

年代:1984

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198400581

出版商:Hüthig&Wepf Verlag    

年代:1984

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198400591

出版商:Hüthig&Wepf Verlag    

年代:1984

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198400601

出版商:Hüthig&Wepf Verlag    

年代:1984

数据来源: WILEY