Affiliation: | 1. Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141 Republic of Korea Department of Chemistry, Korea Advanced Institute of, Science and Technology (KAIST), Daejeon, 34141 Republic of Korea;2. Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141 Republic of Korea |
Abstract: | While numerous organo(metallic)catalyst systems were documented for dearomative hydroboration of N-aromatics, alkoxide base catalysts have not been disclosed thus far. Described herein is the first example of alkoxide-catalyzed hydroboration of N-heteroaromatics including pyridines, providing a broad range of reduced N-heterocycles with high efficiency and selectivity. Mechanistic studies revealed an unprecedented counterintuitive dearomatization pathway, in which 1) pyridine-BH3 adducts undergo a hydride attack by alkoxyborohydrides, 2) in situ generated BH3 serves as a catalytic promoter, and 3) 1,4-dihydropyridyl borohydride is in a predominant resting state. |