Lewis Acid Activation by the Interactions with n Electrons

3 Lewis Acid Activation by the Interactions with n Electrons 359 

An interesting feature of gallium(III) compounds as classified Lewis acids is their ability to interact with unsaturated bonds particularly with alkynes. GaCl3 formed a tt complex with alkynes, which strongly activated the triple bond toward nucleophilic attack. Carbometalation (carbogallation) with alkynes is another characteristic reaction of organogallium(III) compounds, and it is likely that the initial step for this reaction is the interaction of the tt electrons of alkynes with the Lewis acid gallium (III) center. 

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