N-Heterocyclic Carbenes Synthesis and Stereoelectronic Parameters

Introduction to N-Heterocyclic Carbenes Synthesis and Stereoelectronic Parameters 

Institut fiir Anorganische und Analytische Chemie, Westfalische Wilhelms-Universitat Munster, Corrensstrasse 30, D-48149 Munster, Germany 

Chemists have been fascinated with carbenes for more than 150 years. The simplest member of this class of compounds, possessing a neutral divalent carbon atom and six electrons in its valence shell, is methylene, CH2. Numerous attempts to isolate methylene or related compounds failed, although carbenic reactivity of methylene derivatives was described in connection with cyclo-propanation reactions as early as 1953. 

In 1964, Fischer prepared and characterized unambiguously the first metal carbene complex 3 obtained by nucleophilic attack of phenyl lithium at 

N-Heterocyclic Carbenes From Laboratory Curiosities to Efficient Synthetic Tools 

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