Disubstituted Carbenium Ions as Reactive Intermediates in Organic Chemistry
نویسندگان
چکیده
Recent results in the chemistry of disubstituted carbenium ions (vinyl cations and phenyl cations) are described separately under three different sections: From kinetic and solvolytic data of several 1—cyclobutenyl nonaflates, the intermediacy of a non-classical vinyl cation, namely the 1-cyclobutenyl cation 2 is established. Cycloaddition reactions of solvolytically generated vinyl cations with olef ins to form cyclobutenyland cyclopropyl compounds are described and the mechanisms of the cycloaddition reactions are discussed. Phenyl cations have been generated by a novel route involving triple bond participation with vinyl cations. INTRODUCTION Disubstituted carbenium ions are an important class of reactive intermediates. Vinyl cations are the most illustrative examples of disubstituted carbenium ions and have been investigated very intensively during the last fifteen years (Ref. 1). In connection with our work on vinyl cations, some new results on the generation of phenyl cations, which also belong to disubstituted carbenium ions, will also be reported. Vinyl cations 1 can be generated by a variety of methods, e.g. by the addition of electrophilic reagents to allenic or acetylenic bonds, by triple bond participation in a carbenium ion reaction, or by heterolysis of vinyl sulfonate esters. We shall be concentrating mostly on the latter mode of generation of vinyl cations (Scheme 1). E + E Y R-CEC-R' + E — C=C-R' +Y R' la / + N' +YN C=CC + E — C=C-C CC / E / lb
منابع مشابه
Carbenium and carbonium ions in liquid- and solid-superacid-catalyzed activation of small alkanes*
Acid-catalyzed hydrocarbon reactions involve by far the largest amount of catalyst and the largest volume of transformation in oil refinery and chemical industry. However, despite the general agreement on the carbocationic nature of the reaction intermediates, the initial steps and the true nature of the cations on the surface are still open to debate. On these points our basic knowledge has ga...
متن کاملThree-Component and Click Strategy for Synthesis of β-Hydroxy 1,4-Disubstituted 1,2,3-Triazoles Derivatives Catalyzed by 1,4-Dihydroxyanthraquinone-copper(II) Complex onto Nano AlPO4
In this work, copper(II) heterogeneous nanocatalyst supported on modified AlPO4 (Cu(II)-DA@Nano AlPO4) was used for the synthesis of some biological active heterocyclic molecules, particularly for the efficient conversion of a wide range of non-activated terminal alkynes to β-hydroxy 1,4-disubstituted 1,2,3-triazolethrough a three-component “click” reaction at room temperature in water. The reg...
متن کاملCharacterization and Investigation of Benzylic Carbenium Ion and Carbanion Ion-diradical Intermediates with 3,5- Disubstiuted Π–donors/acceptors
Title of Document: CHARACTERIZATION AND INVESTIGATION OF BENZYLIC CARBENIUM ION AND CARBANION ION-DIRADICAL INTERMEDIATES WITH 3,5DISUBSTIUTED π–DONORS/ACCEPTORS Raffaele Romano Perrotta, Doctor of Philosophy, 2012 Directed by: Professor Daniel E. Falvey Department of Chemistry & Biochemistry High-spin magnetic materials have been based on monomeric units that contain metals. Far less research ...
متن کاملSelenium Stabilized Carbenium Ions on Organic Synthesis
Organoselenium compounds have been known for a long time as versatile reagents in organic chemistry. In the last years there has been a considerable development of selenium-based methods for organic synthesis. Many of these methods are currrently been used as standard procedures to introduce new functional groups under mild conditions. From the several areas of interest in organoselenium chemis...
متن کاملSynthesis of 1,5 and 2,5-disubstituted tetrazoles using NiO nanoparticles and their evaluation as antimicrobial agents
Treatments of tetrazolate salts prepared in situ from various aldehyde; malononitrile and sodium azide in the presence of NiO nanoparticles with benzyl bromide gave the corresponding 1,5- and 2,5-disubstituted tetrazoles. Reaction of tetrazolate salts with 2,4′-dibromoacetophenone in the presence of NiO nanoparticles provided the corresponding 2,5-disubstituted derivatives as an only isomer. T...
متن کامل