Lithium dihydropyridine dehydrogenation catalysis : a group 1 approach to cyclisation of diamine-boranes

McLellan, Ross and Kennedy, Alan R. and Orr, Samantha A. and Robertson, Stuart D. and Mulvey, Robert E. (2017) Lithium dihydropyridine dehydrogenation catalysis : a group 1 approach to cyclisation of diamine-boranes. Angewandte Chemie International Edition, 56 (4). pp. 1036-1041. ISSN 1433-7851

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    Abstract

    In reactions restricted previously to a ruthenium catalyst, a 1-lithium-2-alkyl-1,2-dihydropyridine complex is shown to be a competitive alternative dehydrogenation catalyst for the transformation of diamine boranes to cyclic 1,3,2-diazaborolidines, which can in turn be smoothly arylated in good yields. This study establishes the conditions and solvent dependence of the catalysis via NMR monitoring, with mechanistic insight provided by NMR (including DOSY) experiments and X-ray crystallographic studies of several model lithio intermediates.