Abstract
The thorium methyl and hydride complex (C5Me5)2ThMe2 and [(C5Me5)2Th(H)(μ-H)]2 catalyzed highly 1,2-regioselective dearomatization of pyridines via a hydroboration process is reported herein. Twelve different kinds of meta- and para-substituted pyridines are applicable to this reaction, giving the corresponding N-boryl-1,2-dihydropyridine products in high yields. Other N-heteroaromatic compounds, such as benzo-fused N-heterocycles, pyrazines, pyrimidines, 1,3,5-triazine, and benzothiazole, were also found to be hydroborated with high chemoselectivity. Kinetics including isotope effect studies revealed a first-order dependence on the concentration of catalyst, pyridine, and pinacolborane, with release of the dearomatized final product as the rate-determining step. A plausible mechanism is proposed on the basis of stoichiometric reactions and kinetic studies.
Original language | English |
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Pages (from-to) | 3673-3677 |
Number of pages | 5 |
Journal | ACS Catalysis |
Volume | 8 |
Issue number | 4 |
DOIs | |
State | Published - 6 Apr 2018 |
Externally published | Yes |
Keywords
- 1,2-regioselective
- N-heteroaromatic
- dearomatization
- pyridine
- thorium