Examination of the Aromatic Amination Catalyzed by Palladium on Charcoal

Abstract

Abstract:The Buchwald-Hartwig amination of aryl halides with secondary amines and functionalized aromatic amines catalyzed by solid-supported palladium is reported. The choices of ligand, base and solvent are crucial for the successful coupling. The amination of aromatic iodides, bromides and chlorides can be easily achieved with palladium on charcoal in the presence of a biphenylphosphane-type ligand at 80-110 8C. In addition, the palladium on charcoal catalyst is easily separable after the reaction, and reusable several times with only small activity loss.

Development of the Applications of Palladium on Charcoal in Organic Synthesis

“…Two years later, Novak's group reported the improved Pd/C‐catalyzed Buchwald–Hartwig amination of secondary amines or functionalized aromatic amines with aryl halides (including the use for the first time of aryl iodides in C–N coupling) in the presence of a biphenylphosphane‐type ligand and NaO‐ t‐ Bu in t‐ BuOH at 80 °C [Eq. (25)] . Apart from aromatic halides, the Pd/C‐catalyzed C–N coupling of amines or nitro compounds with alcohols and phenols has also been reported.…”

Synthesis of Arylamines via Non‐Aerobic Dehydrogenation Using a Palladium/Carbon‐Ethylene System

“…N ‐(3,5‐Dimethylphenyl)morpholine : yellow liquid. IR (neat) 556, 666, 693, 826, 872, 930, 959, 1016, 1070, 1120, 1195, 1262, 1303, 1348, 1376, 1449, 1475, 1593, 2818, 2851, 2914, 2955, 3013; 1 H NMR (400 MHz, CDCl 3 ), δ=2.31 (s, 6H), 3.15 (t, 4H), 3.87 (t, 4H), 6.57 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ=21.6, 49.5, 67.0, 113.7, 122.0, 138.7, 151.4.…”

2,6‐Diisopropoxyphenyl(dicyclohexyl)phosphine: A New Ligand for Palladium‐Catalyzed Amination Reactions of Aryl Chlorides with Potassium Hydroxide as the Base

“…Bis(4‐acetophenyl)amine (3w): The reaction of 1l (155.7 mg, 1.0 mmol), 2i (163.4 mg, 1.2 mmol), Pd(OAc) 2 (6.8 mg, 0.030 mmol), L2 ⋅ HBF 4 (21.6 mg, 0.045 mmol), and KOH (112.9 mg, 2.0 mmol) in 5 mL of toluene at 110 °C under nitrogen afforded 3w 32 after work‐up (eluent: petroleum ether/ethyl acetate/CH 2 Cl 2 =3/1/1) as a solid; yield: 214.6 mg (84%); mp 155.9–157.3 °C ( n ‐hexane/CH 2 Cl 2 , lit: 117–119 °C, no solvents information). 1 H NMR (300 MHz, CDCl 3 ): δ =7.95–7.88 (m, 4 H), 7.20–7.14 (m, 4 H), 7.00 (bs, 1 H), 2.55 (s, 6 H); 13 C NMR (75 MHz, CDCl 3 ): δ =196.6, 146.0, 130.5, 130.4, 116.8, 26.2; IR (KBr): ν=3310, 3192, 3100, 2992, 1679, 1657, 1609, 1584, 1527, 1428, 1353, 1341, 1306, 1275, 1250, 1173, 1075, 1021 cm −1 ; MS (70 eV, EI): m / z (%)=254 (M + +1, 9.31), 253 (M + , 51.12), 238 (100).…”