Unnikrishnan, Anju ; Sunoj, Raghavan B. (2021) Iridium-Catalyzed Regioselective Borylation through C–H Activation and the Origin of Ligand-Dependent Regioselectivity Switching Journal of Organic Chemistry, 86 (21). pp. 15618-15630. ISSN 0022-3263
Full text not available from this repository.
Official URL: http://doi.org/10.1021/acs.joc.1c02126
Related URL: http://dx.doi.org/10.1021/acs.joc.1c02126
Abstract
Research efforts in catalytic regioselective borylation using C–H bond activation of arenes have gained considerable recent attention. The ligand-enabled regiocontrol, such as in the borylation of benzaldehyde, the selectivity could be switched from the ortho to meta position, under identical conditions, by just changing the external ligand (L) from 8-aminoquinoline (8-AQ) to tetramethylphenanthroline (TMP). The DFT(B3LYP-D3) computations helped us learn that the energetically preferred catalytic pathway includes the formation of an Ir−π-complex between the active catalyst [Ir(L)(Bpin)3] and benzaldimine, a C–H bond oxidative addition (OA) to form an Ir(V)aryl-hydride intermediate, and a reductive elimination to furnish the borylated benzaldehyde as the final product. The lowest energetic span (δEortho = 26 kcal/mol with 8-AQ) is noted in the ortho borylation pathway, with the OA transition state (TS) as the turnover-determining TS. The change in regiochemical preference to the meta borylation (δEmeta = 26) with TMP is identified. A hemilabile mode of 8-AQ participation is found to exhibit a δEortho of 24 kcal/mol for the ortho borylation, relative to that in the chelate mode (δEortho = 26 kcal/mol). The predicted regioselectivity switching is in good agreement with the earlier experimental observations.
Item Type: | Article |
---|---|
Source: | Copyright of this article belongs to American Chemical Society. |
ID Code: | 124364 |
Deposited On: | 18 Nov 2021 12:11 |
Last Modified: | 18 Nov 2021 12:11 |
Repository Staff Only: item control page