摘要:

AbstractTetra‐tert‐butyltetrahedrane—a useless molecule? In the first part of this progress report an attempt is made to answer this provoking question in order that the reader can evaluate why it is worthwhile to track such an esoteric molecule. An account of the unusual properties of tetra‐tert‐butyltetrahedrane, the only tetrahedrane unequivocally identified so far, and the most highly strained saturated hydrocarbon of all, is followed by a summary of attempts to synthesize the parent compound. The emphasis in these two sections is on our own research achievements. Since any discussion of the tetrahedranes must necessarily include the corresponding cyclobutadienes, it was found appropriate to organize the article at the same time as a final account of the cyclobutadiene problem.Masamune[8c]characterized his excellent report in 1980 in the journal Tetrahedron as acommain the history of cyclobutadiene. Meanwhile, the significant questions have been answered. The time is now ripe to replace the comma by a

ISSN:0570-0833    

DOI:10.1002/anie.198803093

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThere has recently been a revival of interest in microbial biochemistry. Part of this resurgence is due to the increased presence of man‐made organic compounds in the biosphere and the resultant interest in microorganisms which can degrade these xenobiotic molecules. Also, advances in genetic engineering have raised the possibility of utilizing the chemical machinery of bacteria for commercial profit and social benefit. The Baeyer‐Villiger reaction is a useful transformation in organic synthesis which provides chemists with a gentle means of converting ketones into esters or lactones. The reaction, however, suffers from the problems of low yield and the need, in some cases, to utilize harsh conditions. There exist bacteria, capable of growth on aliphatic molecules, that contain enzymes which can catalyze Baeyer‐Villiger reactions. These enzymes, known as monooxygenases, are involved in the breakdown of acyclic and alicyclic ketones to provide simpler carbon units for further catabolism. The gamut of reactions catalyzed by some of these enzymes is remarkable. This diversity, plus their availability in pure form in quantity by genetic engineering raises the possibility that these biocatalysts can be useful as reagents in organic synt

ISSN:0570-0833    

DOI:10.1002/anie.198803331

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe functions of iron in biology are often associated with heme or iron‐sulfur proteins. But dioxygen transport, reduction of ribo‐ to deoxyribonucleotides, acid phosphatase activity, oxidation of methane to methanol, and iron storage are amont the growing list of biological phenomena known or believed to be associated with a newly emerging class of proteins having oxo‐bridged di‐ or polyiron aggregates at their metallic cores. The recognition of these iron–oxo proteins as a separate class has stimulated efforts on the part of inorganic chemists to prepare and characterize model compounds that replicate the physical properties and functions of the polymetallic protein cores. As a consequence, a variety of new oxo‐bridged di‐, tri‐, tetra‐, hexa‐, octa‐, and undecairon aggregates has been synthesized. These novel molecules promise not only to provide insight into the detailed characteristics of the metal centers in iron–oxo proteins, but also to serve as a focal point for preparing new materials, including oxidation catalysts and corrosion inhibitors, for the evolution of new theories to describe their physical properties, for developing new strategies for the treatment of iron‐related disease, and for building links between the chemistry of the bi

ISSN:0570-0833    

DOI:10.1002/anie.198803441

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractSince the discovery of the crown ethers byPedersentwenty years ago, the chemistry of synthetic hosts for the selective complexation of organic and inorganic guests has seen an extraordinarily rapid development. This article discusses in particular the contributions provided by synthetic cyclophanes as hosts to the understanding of molecular complexation of neutral organic guest molecules in aqueous and organic solvents. In aqueous solution, cyclophanes form stoichiometric complexes with neutral aromatic guests which can approach enzyme‐substrate complexes in their stability. Efficient molecular complexation is also observed in organic environments. Here, as a result of large solvation effects, the strength of complexation is strongly dependent on the nature of the organic solvent. Electron donor‐acceptor interactions can contribute significantly to the stability of complexes formed between cyclophane hosts and aromatic guests. Force‐field calculations together with computer graphics are powerful tools in the design of water‐soluble, optically active hosts for chiral recognition of complexed racemic guests. Simple and selective functionalization of the cyclophane framework leads to stable, bioorganic catalysts. Like enzymes, these catalysts bind their substrates in a rapid equilibrium prior to the reaction steps. As a perspective, some fascinating research objectives in the field of molecular recognition and catalysis which can be targeted with designed cyclophane hosts ar

ISSN:0570-0833    

DOI:10.1002/anie.198803621

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198803871

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198803891

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198803911

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198803921

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198803931

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198803941

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY