Selective dearomatization of N-heteroarenes has recently attracted much interest from researchers because the resulting products are useful building blocks to synthesize valuable pharmaceutical or natural compounds. In this context, the catalyst plays the key role to control the selectivity. In this thesis, we developed 1,2-selective dearomatizations of N-heteroarenes using iridium and N-heterocyclic carbene catalysts. We studied functional group tolerance, mechanism determining the selectivity, and the applicability in our catalytic systems.
In the first study, we developed 1,2-hydrosilylation of pyridines and quinolines via transition metal catalyst. While several catalytic systems have been developed for the selective dearomatization of pyridines via 1,4-hydrosilylation, but no catalytic system through 1,2-hydrosilylation has been reported. On the basis of mechanistic assumption, we discovered the first catalytic system for 1,2-hydrosilylation of pyridines and quinolines using commercially available iridium precursor and silane.
In the second study, we developed 1,2-hydroboration of quinolines with N-heterocyclic carbene. The previous catalytic systems were problematic in applications toward dearomatization of complex N-heterocycles due to the low regioselectivity and lack of functional group tolerance. To overcome these issues, we developed 1,2-hydroboration of quinolines using neutral Lewis base, N-heterocyclic carbene, displaying the high regioselectivity and good functional group compatibility.