Straightforward Synthesis of Aromatic Imines from Alcohols and Amines or Nitroarenes Using an Impregnated Copper Catalyst

Abstract

The impregnated copper on magnetite catalyst is a versatile system for the synthesis of imines starting from alcohols and amines. This catalyst does not require any type of expensive and difficult to handle organic ligand or typical transition metals, and provides excellent yields achievable under mild reaction conditions. Moreover, the catalyst is very easy to remove from the reaction medium by simply using a magnet. The one‐pot process of dehydrogenation of alcohols in the presence of aniline followed by aqueous hydrolysis gave pure alcohols in excellent yields. In addition to amines, nitroarenes could be used as the nitrogen‐containing reagent. In the case of primary amines the expected imines were successfully prepared under similar reaction conditions.

Recent Advances in Aerobic Oxidation of Alcohols and Amines to Imines

“…20 The reactions, however, were performed under an inert atmosphere, and stoichiometric NaOH was added in both the self-coupling of amines and cross-coupling of alcohol with amines. Besides, it should be pointed out that the presence of nitrogen-containing compounds can increase the particle size of CuO and promote the copper leaching by formation of copper complexes.…”

Copper/Imidazolium/TEMPO-Catalyzed Aerobic Oxidation of Benzylic Alcohols­ in Water

“…13 C NMR (100 MHz, CDCl 3 ): δ = 190.3, 165.9 (d, J C-F = 258.4 Hz), 132.1 (d, J C-F = 10.9 Hz), 130.4 (d, J C-F = 2.8 Hz), 128.2 (d, J C-F = 11.2 Hz), 121.3 (d, J C-F = 23.9 Hz), 115.8 (d, J C-F = 21.3 Hz).3,4-Dichlorobenzaldehyde (2n)22 White solid; yield: 108 mg (62%) 1. H NMR (400 MHz, CDCl 3 ): δ = 9.95 (s, 1 H), 7.96 (s, 1 H), 7.72 (d, J = 8.4 Hz, 1 H), 7.63 (d, J = 7.6 Hz, 1 H).…”

C‐N Bond Formation Catalyzed by Ruthenium Nanoparticles Supported on N‐Doped Carbon via Acceptorless Dehydrogenation to Secondary Amines, Imines, Benzimidazoles and Quinoxalines

“…The nature of substituents had a similar influence on product yields as was observed with the corresponding ATH reactions. As displayed in Table S3, the turnover number (TON) and turnover frequency (TOF) of Ru/N−C (TON=450, TOF=18.8 h −1 ) were higher than those of Pd/DNA (TON=33, TOF=2.8 h −1 ; DNA=fish sperm DNA), Ag/Al 2 O 3 (TON=15.8, TOF=0.7 h −1 ), Cu‐Fe 3 O 4 (TON=75.4, TOF=0.8 h −1 ), and TiO 2 /PMHSIPN (TON=470, TOF=3.98 h −1 ; PMHSIPN=polymethylhydrosiloxane‐based semi‐interpenetrating networks) …”