Palladium catalysed aryl amination reactions in supercritical carbon dioxide

Abstract

Palladium catalysed C-N bond formation in supercritical carbon dioxide has been accomplished. Carbamic acid formation is avoided in part through the use of an N-silylamine as the coupling partner. Employing a catalyst system of Pd2dba3(1 mol%) and 2-dicyclohexylphosphino-2',4',6'-triisopropyl-1,1'-biphenyl (X-Phos)(2 mol%) enabled the catalytic amination of aryl bromides and chlorides with N-silylanilines to be realised in excellent yield. Extension of the methodology to the N-arylation of N-silyldiarylamines, N-silylazoles and N-silylsulfonamides is reported.

Biaryl Phosphane Ligands in Palladium‐Catalyzed Amination

“…[243] Another area of reaction development has been in the application of supercritical carbon dioxide (scCO 2 ) as solvent for the palladium-catalyzed amination of aryl halides using biaryl phosphine ligands (Scheme 71). [244,245] Holmes showed that for successful reaction to occur in this medium it is necessary to protect the amine with a trimethylsilyl group. The authors hypothesize that this is necessary to prevent carbamate formation from occurring.…”

Recent Advances in Palladium‐Catalyzed Carboxylation with CO2

“…In path a, the oxidative addition of an aryl halide to Pd 0 species 9 gives ArPdX(Xphos) (10), which generates (ArCOO)PdX(Xphos) (11) in the presence of CO 2 . In path a, the oxidative addition of an aryl halide to Pd 0 species 9 gives ArPdX(Xphos) (10), which generates (ArCOO)PdX(Xphos) (11) in the presence of CO 2 .…”

“…[10] In the protocol, the methodology was extended to the N-arylation of N-silyldiarylamines, N-silylazoles, and N-silylsulfonamides. [10] In the protocol, the methodology was extended to the N-arylation of N-silyldiarylamines, N-silylazoles, and N-silylsulfonamides.…”

Carbene adduct of cyclopalladated ferrocenylimine as an efficient catalyst for the amination of aryl chlorides

“…N-Methyl-N-phenyl-2-methoxyaniline (Table 3, entry 5) [26]. Pale yellow oil; 1 H NMR: d 7.19-7.12 ( 4H, m), 6.95-6.94 (2H, m), 6.70 (1H, t, J = 7.3 Hz), 6.64-6.62 (2H, m), 3.72 (3H, s), 3.19 (3H, s).…”