R. Liu et al, Org. Lett. 2024, 26, 9847−9851
https://doi.org/10.1021/acs.orglett.4c03625
Efficient methods for preparing electron-deficient (hetero)aryl anilines are limited. This paper by the Liu group describes a operationally simple method for synthesizing primary anilines from (hetero)aryl boronic acids and esters using commercially available O-(diphenylphosphinyl)hydroxylamine (DPPH) under mild, metal-free conditions. The transformation occurs efficiently at room temperature (DPPH, KOH, CH3CN) with high functional group tolerance and is particularly effective for electron-deficient substrates—an area where existing methods often struggle. The reaction proceeds via a proposed mechanism involving a 1,2-aryl shift from boron to nitrogen, followed by hydrolysis. Experimental data, including a Hammett study, reveal that the reaction rate is largely insensitive to the electronic properties of the aryl group, distinguishing it from similar transformations. The DPPH reagent also works with boronic esters and heterocycles, including challenging nitrogen-containing compounds.
- Metal-free direct transformation of aryl boronic acid to primary amines: V. Verma et al, J. Org. Chem. 2022, 27, e202200508
- Reductive molybdenum-catalyzed direct amination of boronic acids with nitro compounds: S. Suarez-Pantiga et al, Angew. Chem. Int. Ed. 2019, 131, 2151-2155
- Aminative Suzuki–Miyaura coupling: R. Liu et al, Science 2024, 383, 1019-1024
