ISSN:0570-0833    

DOI:10.1002/anie.197705593

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractSubstituents capable of stabilizing negative charge endow ethylene oxides with the ability to undergo electrocyclic ring opening at the CC bond; heating or irradiation generates small equilibrium concentrations of carbonyl ylides which can engage in 1,3‐dipolar cycloadditions. Apart from the normal conrotatory mode of ring opening, predicted by the Woodward‐Hoffmann rules, the disrotatory process, forbidden by orbital symmetry, also appears to occur in the case of α‐cyano‐cis‐stilbene oxide. Kinetic studies on α‐cyano‐trans‐and ‐cis‐stilbene oxide permit construction of the energy profile for electrocyclic ring opening to give the stereoisomeric carbonyl ylides and for their recyc

ISSN:0570-0833    

DOI:10.1002/anie.197705721

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractThe progress of macrolide chemistry and biochemistry over the past several years has indeed been remarkable. This review attempts to cover the important contributions which have been made in the fields of structural and synthetic chemistry as well as in the biosynthesis and mode of antimicrobial activity of the “polyoxo” macrolide antibiotics. Emphasis has been placed on the recent synthetic achievements in this fi

ISSN:0570-0833    

DOI:10.1002/anie.197705851

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractSalt solutions can be separated into pure water and concentrated salt solution by reverse osmosis using semipermeable membranes. The distinct features and limitations of osmotic separations are developed from a consideration of the pertinent solution properties and the conditions inherently to be met by the membranes, seen as interacting barrier phase in a process which substantially separates water from water.

ISSN:0570-0833    

DOI:10.1002/anie.197706071

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractMolecules change their properties on acquisition or loss of energy. The state of a molecule can be characterized by the difference between its energy and that of the preceding initial state or that of the subsequent final state, as well as by the respective charge distribution. Molecules in their various energy states each display a particular structure and characteristic properties, and it is these entities which the chemist uses as synthetic building blocks.—The best model hitherto available for describing molecular states is the molecular orbital representation. Molecular orbitals are especially suitable for comparing mutually corresponding molecular states of similar compounds, and thus provide a manifold and stimulating overview of large areas of chemistry.—An attempt will now be made to point out important characteristic parameters of molecular states and to explain the rules governing their description by molecular orbitals, while circumventing mathematical barriers. A principal objective is the comparison of states of “chemically related” molecules with regard to the connection, the arrangement, and the potential of their atoms. The simple models employed for this purpose, whose inherent limitations and potential expansions are discussed, have meanwhile become valuable tools in the hand of the

ISSN:0570-0833    

DOI:10.1002/anie.197706131

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197706371

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197706392

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197706401

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197706411

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197706421

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY