3-tert-Butyl-Substituted Cyclohexa-1,4-dienes as Isobutane Equivalents in the B(C6F5)3-Catalyzed Transfer Hydro-tert-Butylation of Alkenes

Cyclohexa-1,4-dienes with a tert-butyl group at C3 are shown to function as isobutane equivalents when activated by the strong boron Lewis acid tris(pentafluorophenyl)borane. The hitherto unprecedented transfer hydro-tert-butylation from one unsaturated hydrocarbon to another is achieved with 1,1-diarylalkenes as substrates, thereby presenting itself as a new way of incorporating tertiary alkyl groups into carbon frameworks. Transient carbocation intermediates give rise to competing reaction pathways that could not be fully suppressed.