The bis(imino)acenaphthene (BIAN) is a remarkable ligand from the standpoint of reactivity. It is well known that the BIAN ligand class will undergo the sequential addition of as many as four electrons. Furthermore, this interesting behavior has resulted in extensive use of this redox-active ligand. Recently, there has been a focus on the functionalization of the BIAN ligand class. In this context, we have demonstrated the radical backbone dearomatization, two-electron reduction of the redox-active BIAN ligand. Moreover, BIAN ligands can also be functionalized by nucleophilic attack on the imino carbon atom, which results in the formation of chiral amido-imine BIAN derivatives. We have discovered a method for controlling this functionalization by sterically directing these reactions to proceed either via a radical backbone dearomatization pathway or a nucleophilic imine C-alkylation pathway. This pathway differentiation has been examined by means of single-crystal X-ray diffraction in conjunction with EPR spectroscopy. Furthermore, computational modeling has been employed to explain the observed reactivity patterns and to obtain an enhanced understanding of the driving forces involved in the reactivity patterns of BIAN functionalization.

Sterically directed functionalization of bis(imino)acenaphthene: Radical dearomatization vs. nucleophilic imine C-alkylation

247th National Meeting (2014)

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