Electro-Organic Reactions. Part 48: Pathways for Carbon-Carbon Bond Formation: The Redox Chemistry of Quinodimethanes and of Alkenyl-Substituted Heteroaromatics
Carbon-carbon bond-forming reactions involving cathodic reduction of quinonemethides, electrogeneration of quinodimethanes and reduction of some vinylpyridines and vinylquinolines, are compared and contrasted. The quinonemethides undergo “conventional” electrohydrodimerisation via radical-anion coupling. Quinodimethanes (QDMs), formed by cathodic elimination from 1,4- and 1,2-di-(halomethyl)arenes, react usefully to give polymers or, for o-quinodimethanes, as dienes in Diels-Alder reactions. QDMs are electroactive and have been characterised electrochemically and spectroscopically. The vinylheteroaromatics give trans-1, 2-diheteroarylcyclobutanes as major products and these are shown to arise from an overall 0 F reaction (catalytic chain process) but with the key initial step being reaction between radical-anion and the neutral starting material.
KeywordsMaleic Anhydride Fumaric Acid Cathodic Reduction Benzyl Bromide Redox Catalysis
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