摘要:

AbstractManaging thermally controlled nuclear fusion will certainly be regarded one day as one of the most successful accomplishments in nuclear physics. At the same time, however, it will represent a technical achievement unparalleled in the history of science and engineering. This in turn would mean, in retrospect, that decisive contributions had to come from a number of disciplines as diverse as materials and engineering sciences and classical chemistry, and that the same collaboration will have to continue in the future in order to reach the ultimate goal, to construct a reactor capable of producing energy from almost inexhaustible source materials (fuels), such as deuterium and lithium. What is the chemist's role in this development? Similarly as in the development of fission reactors, i.e., the nuclear power plants currently in operation, chemists will have to ensure the existence of a reliable fuel cycle–starting from the availability, storage and reprocessing of the fuel through to the provision for safe storage of the waste. In this review article an attempt will be made to outline the problems associated with these tasks and the approaches to be made by the chemist in solving the

ISSN:0570-0833    

DOI:10.1002/anie.198900013

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractMain‐chain chirality is the optical activity resulting from the configurational or conformational arrangement in the main chain of a polymer. The chirality of the most important types of structures has been investigated on the basis of systematic considerations of symmetry. This has led to the surprising result that even in polymers derived from 1‐substituted or nonsymmetric 1,1‐disubstituted olefins (the technologically most important polymers) several types of chiral structures exist, which are expected to result in optical activity if a particular enantiomer is favorably formed. By carrying out an asymmetric cyclopolymerization, it has been possible to obtain certain structural types in the form of optically active copolymers or homopolymers (e.g., copolymers of styrene with methyl methacrylate, or even the homopolymer of styrene). Another new group of optically active polymers consists of the atropisomeric helical polyisocyanides, poly(trityl methacrylates), and polychlorals. Optically active polymers are already used as adsorbents for the chromatographic separation of racemic mixtures. Further applications are likely to e

ISSN:0570-0833    

DOI:10.1002/anie.198900211

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractMetallo‐ene reactions, hardly recognized until very recently, have experienced a breathtaking development when applied in an intramolecular sense. Efficient regio‐ and stereoselective magnesium‐ene cyclizations have served as a cornerstone for numerous syntheses of structurally diverse natural products (e.g., sesquiterpenes of marine or plant origin, alkaloids, fragrances, insect defense compounds, and a fungitoxin). A brilliant example is the synthesis of the elusive odorant (+)‐khusimone which outshines 20 years of work in the field of tricyclovetivane synthesis. Palladium‐, platinum‐, and nickel‐catalyzed versions of the metallo‐ene reaction are in a comparatively early stage of exploration, but, nevertheless, reveal intriguing potential. Hence an almost 100% stereospecific CO→C;Pd‐→ CC chirality transfer permits simple and selective,cis‐ ortrans‐annelation processes. The mild cyclization conditions are compatible with various functional groups, such as nitrogen moieties, which offer interesting perspectives for the preparation of heterocycles (e.g., alkaloids) difficult to obtain by other methods. Carbon monoxide insertion reactions of the cyclized σ‐metal intermediates were shown to afford annelated cyclopentanones and cyclopentenones with concomitant stereocontrolled formation of four carbon–carbon bonds. These and other observations, highlighted in this article, provide a platform for further extensions and applications of this

ISSN:0570-0833    

DOI:10.1002/anie.198900381

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198900531

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198900541

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198900551

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198900561

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198900581

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198900601

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198900611

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY