N-Methylation of ortho-substituted aromatic amines with methanol catalyzed by 2-arylbenzo[d]oxazole NHC–Ir(iii) complexes

Abstract

By the modification on benzo[d]oxazolyl-NHC-ligated cyclometalated Ir complexes, the N-methylation of ortho-substituted aromatic amines with methanol was remarkably improved.

Simple RuCl3‐catalyzed N‐Methylation of Amines and Transfer Hydrogenation of Nitroarenes using Methanol

“…Later, Watanabe and co‐workers [23] used RuCl 3 .nH 2 O/P(OBu) 3 catalytic system for N ‐methylation of amines with methanol at 180 °C, but the substrate scope is very narrow. After their seminal work, many groups have extended the state of selective N ‐methylation of amines or nitroarenes with methanol in presence of noble‐ [3a–e,h,l‐q,s,u‐z,aa, ac‐ae,24] and non‐noble metals ‐ [3f,g,i–k,r,t, ab, af‐ag] . Regarding ruthenium catalysis, to date only five homogeneous catalytic systems are reported ( Figure 1 ) .…”

Facile synthesis of N-doped graphene encapsulated Pd@N/C catalyst and its efficient application in cascade flow synthesis of amines

“…Surprisingly, the high steric substrate diphenylmethanamine could also be converted to the N, N-dimethyldiphenylmethanamine in a 72% yield. Moreover, the linear branched and cyclic aliphatic amines, furan, thiophene, pyrazole, and pyridine heterocyclic amines, which were previously reported challenging substrates [54][55][56] , were successfully converted to the corresponding N, N-di-methylated products in good to excellent yield (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28). The thin graphene layer encapsulated N-doping catalyst also showed very e cient reactivity and selectivity in the double dimethylation reaction of diamines (31).…”

“…Klankermayer group 15 later also developed a high e cient homogeneous catalyst system for the N-methylation of imines, using Ru (triphos) (tmm) complex and HNTf 2 acid. Up to now, there are many advanced N-methylation synthesis processes using not only homogeneous Ru-complex ([RuCpCl 2 ] 2 /dpePhos 10 , [Ru(p-cymene)I 2 ] 2 16 ) but also other homogeneous metal complex like Ir 17,18 , Rh 19 , Cu 20 , Fe 21,22 , Co 23 , and Mn 24 . In the meantime, the heterogeneous catalyst systems have not only obtained the same rapid development but also attracted more and more attention.…”

Research progress in homogeneous catalysis of <italic>N</italic>-methylation of amine using methanol as carbon source

“…2012年, Kempe课题组 [31] [32] (a)、酶抑制剂TNNI3K [33] (b)和药物洛沙平的合成 [34] (c) Figure 4 The regioselective N-methylation of amines [32] (a), synthesis of biologically active molecular TNNI3K [33] (b) and Loxapine [34] [38] (a)以及双金属和单金属配合物的催化差异 [39] (b) Figure 5 N-methylation of amine using a Ir catalyst [38] (a) and the catalytic difference between bimetallic and monometallic complexes [39] . 然而, 通过单晶结构得到该配合物中的两个Ir 的距离为7.5827 Å, 因此推测可能是一个金属中心独立 工作, 或者只有一个具有活性的金属中心在另一个金 属的电子效应影响下工作(图5(b)).…”