Simple RuCl3‐catalyzed N‐Methylation of Amines and Transfer Hydrogenation of Nitroarenes using Methanol. Issue 7 (25th February 2021)

• Record Type: Journal Article
• Authors: Sarki, Naina; Goyal, Vishakha; Tyagi, Nitin Kumar; Puttaswamy, ; Narani, Anand; Ray, Anjan; Natte, Kishore
• Is Part Of: ChemCatChem. Volume 13:Issue 7(2021)
• Page Start: 1722
• Page End: 1729
• Publication Date: 2021-02-25
• Subjects: Methanol -- RuCl3.xH2O -- N-Methylation -- Transfer hydrogenation -- Pharmaceutical intermediates; Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.202001937
• Languages: English
• ISSNs: 1867-3880

Abstract

Abstract: Methanol is a potential hydrogen source and C1 synthon, which finds interesting applications in both chemical synthesis and energy technologies. The effective utilization of this simple alcohol in organic synthesis is of central importance and attracts scientific interest. Herein, we report a clean and cost‐competitive method with the use of methanol as both C1 synthon and H2 source for selective N ‐methylation of amines by employing relatively cheap RuCl3 .xH2 O as a ligand‐free catalyst. This readily available catalyst tolerates various amines comprising electron‐deficient and electron‐donating groups and allows them to transform into corresponding N ‐methylated products in moderate to excellent yields. In addition, few marketed pharmaceutical agents (e. g., venlafaxine and imipramine) were also successfully synthesized via late‐stage functionalization from readily available feedstock chemicals, highlighting synthetic value of this advanced N ‐methylation reaction. Using this platform, we also attempted tandem reactions with selected nitroarenes to convert them into corresponding N ‐methylated amines using MeOH under H2 ‐free conditions including transfer hydrogenation of nitroarenes‐to‐anilines and prepared drug molecules (e. g., benzocaine and butamben) as well as key pharmaceutical intermediates. We further enable one‐shot selective and green syntheses of 1‐methylbenzimidazole using ortho ‐phenylenediamine (OPDA) and methanol as coupling partners. Abstract : Keep it simple : Readily available RuCl3 .xH2 O served as an excellent ligand‐free catalyst for selective N ‐methylation of amines and transfer hydrogenation of nitroarenes including the synthesis of drug molecules