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In chemistry a carbenoid is a reactive intermediate that shares reaction characteristics with a carbene. [1] In the Simmons–Smith reaction the carbenoid intermediate is a zinc / iodine complex that takes the form of I-CH 2-Zn-I. This complex reacts with an alkene to form a cyclopropane just as a carbene would do.
[citation needed] [18] The transition metal carbene complexes can be classified according to their reactivity, with the first two classes being the most clearly defined: Fischer carbenes, in which the carbene is bonded to a metal that bears an electron-withdrawing group (usually a carbonyl). In such cases the carbenoid carbon is mildly ...
A transition metal carbene complex is an organometallic compound featuring a divalent carbon ligand, itself also called a carbene. [1] Carbene complexes have been synthesized from most transition metals and f-block metals, [2] using many different synthetic routes such as nucleophilic addition and alpha-hydrogen abstraction. [1]
The Charette modification replaces the CH 2 I 2 normally found in the Simmons–Smith reaction with aryldiazo compounds, such as phenyldiazomethane, in Pathway A. [30] Upon treatment with stoichiometric amounts of zinc halide, an organozinc compound similar to the carbenoid discussed above is produced. This can react with almost all alkenes and ...
These reactions have the general features of having an exocyclic leaving group on a carbon adjacent to the ring and an electron donating group on the ring capable of initiating a migration of an endocyclic bond. A common migration introduction of carbon is a pinacol rearrangement. [1]
Bonding scheme of carbene radical complexes as compared to Schrock and Fischer-type carbene complexes. Carbene radicals are a special class of organometallic carbenes.The carbene radical can be formed by one-electron reduction of Fischer-type carbenes using an external reducing agent, or directly upon carbene formation at an open-shell transition metal complex (in particular low-spin cobalt(II ...
The disadvantages of the reaction involve side reactions of the carbene moiety. The choice of solvent for the reaction needs to be considered. In addition to the potential for carbon-hydrogen bond insertion reactions, carbon-halogen carbene insertion is possible when dichloromethane is used as the solvent. [20] C-Cl bond insertion
The carbene carbon of a Fischer carbene is electrophilic in nature. Thus, Fischer carbenes exhibit similar reactivity compared to carbonyl compounds. Many of the reactions can be understood by using the carboxylic equivalent structure such as transesterification, Michael addition, and aldol reaction.