Catalytic reduction of aryl trialkylammonium salts to aryl silanes and arenes

Abstract

Aryl trialkylammonium salts serve as versatile substrates for nickel-catalyzed reductions, allowing access to functionalized arenes and aryl silanes.

Trialkylammonium salt degradation: implications for methylation and cross-coupling

“…19, see Experimental ESI Section 20 † for optimisation). A range of substituents and structural complexities around the phenol ring were tolerated in these methylation reactions, and most with good to excellent isolated yields (17,(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)34). Additionally, thiophenol and benzoic acid could be methylated under the applied conditions to give thioether 32 and ester 33 with good 77% and 80% yields, respectively.…”

“…Applications and divergent reactivity of trialkylammonium salts Trialkylammonium (specically N,N,N-trimethylanilinium) salts have found wide-ranging applications in synthesis, spanning phase-transfer catalysis, 1 supramolecular ion-pairing catalysis, 2,3 host-guest binding studies, 4 O-methylation, 5 O-arylation, 6 heteroatom arylations, 7 C-H methylation, 8 C-arylation, [9][10][11] uorine radiolabeling, [12][13][14][15] organometallic ligand design, [16][17][18][19][20][21] antimicrobial polymer design, 22 arene reduction, 23 pH sensing, 24 and a range of metal-catalysed cross-coupling methodologies. [25][26][27][28][29][30][31][32] The dichotomy of arylation versus methylation reactivity, while important for optimising the above-listed applications, is rarely studied in detail.…”

“…Fig. 1 Demonstration of dichotomous reactivity of trimethylanilinium salts in: (A) C-H methylation, 8 (B) Kumada coupling, 9 (C) arene reduction, 23 (D) silylation, 23 (E) phenol methylation, 5 and (F) alcohol arylation. 6 Part (G) summarises the dual reactivity of trimethylanilinium salts and the key mechanistic problem investigated in this study.…”

“…1, Part A). 8 Pioneering nickel-catalysed arene reduction methods from Rand and Montgomery 23 showed that ligand and solvent variations could be exploited to enable either C-H or C-Si bond formation from the same anilinium salt source (Fig. 1, Parts C and D).…”

Conversion of anilines to chiral benzylic amines via formal one-carbon insertion into aromatic C–N bonds

“…However, the direct cleavage of aromatic carbon–nitrogen bonds is challenging due to the particularly inert and stable nature of these bonds 22 , 23 . Although aromatic carbon–nitrogen bonds can be activated by converting anilines to more reactive intermediates such as aryldiazonium salts 24 – 27 , arylammonium salts 28 – 30 , amides 31 , 32 , or triazenes 33 , the nitrogen atom is usually discarded in byproducts (Fig. 1b ).…”