The mechanism of an unusual Cu(I)-catalyzed 1,3-bromine migration was investigated using quantum chemical calculations. The reaction involves the displacement of a benzylic copper by an adjacent aryl bromide through a series of formal sigmatropic shifts along an unusual dearomative pathway to yield an intermediate containing a benzyl bromide and an aryl copper. In contrast to most first-row transition metals, which undergo one-electron oxidation state changes, this pathway appears to involve no oxidation state changes at the copper center. Our calculations indicate that the dearomative step and 1,2-bromine shift to copper occurs on a relatively flat potential energy surface before restoring aromaticity in an exergonic step. The final step involving a 1,4-bromine migration from copper to the benzylic carbon was found to be the stereoablative step for this reaction. Our current model and ongoing work on this reaction will be presented.

Computational mechanistic investigation of a Cu(I)-catalyzed 1,3-halogen migration

249th National Meeting (2015)

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