PdI2 as a Simple and Efficient Catalyst for the Hydroamination of Arylacetylenes with Anilines

Abstract

The hydroamination reaction is a convenient alternative strategy for the formation of C–N bonds. Herein, we report a new versatile and convenient protocol for the hydroamination of arylacetylenes with anilines using palladium iodide in the absence of any added ligand as catalyst. Mild conditions, excellent regio- and stereoselectivity, and high functional group tolerance are the main features of this methodology. A subsequent reduction step gives access to a wide variety of secondary aromatic amines.

Ag(I) Complexes of Imine Derivatives of Unexpected 2-Thiophenemethylamine Homo-Coupling and Bis-(E)-N-(furan-2-ylmethyl)-1-(quinolin-2-yl)methanimine

“…The preparation of Schiff bases can proceed by the condensation reaction of carbonyl compounds with primary amines. Apart from the condensation reaction commonly used in the synthesis of Schiff bases, other synthetic methods have been reported, such as the reductive imination of nitro compounds [3], rebound hydrolysis [4], hydroamination of alkynes with anilines [5], oxidative coupling of alcohols and amines [6] and cross-coupling of amines [7,8].…”

Regioselective Mercury(I)/Palladium(II)-Catalyzed Single-Step Approach for the Synthesis of Imines and 2-Substituted Indoles

“…Since modest efficiency of the mixture of the catalyst and oxidant agent Pd(OAc) 2 /Cu(OAc) 2 was achieved for the one-pot conversion of anilines and ketones to indoles in only two cases [ 66 ], the Hg(I)-free reaction of aniline 1i with 2a in the presence of the Pd(OAc) 2 /Cu(OAc) 2 couple was also tested. However, no indole was found [ 51 ]. Indeed, the alkyne was consumed only to generate 1,4-diphenylbuta-1,3-diyne, being the well-known, palladium-catalyzed, self-coupling product of terminal alkynes [ 94 ].…”

“…-2’), 20.9 ( CH 3 Ar), 119.4 (C-2), 127.1 (C-2”), 128.3 (C-3”), 129.5 (C-3), 130.3 (C-4”), 132.6 (C-4), 139.7 (C-1”), 149.0 (C-1), 165.5 (C-1’). HRMS (EI): m/z [M + ] calcd for C 15 H 15 N: 209.1204; found: 209.1210 [ 51 ].…”

“…13 C NMR (150 MHz, CDCl 3 ): δ 17.3 (C-2’), 55.5 ( CH 3 O), 114.2 (C-3), 120.7 (C-2), 127.1 (C-2”), 128.3 (C-3”), 130.3 (C-4”), 139.8 (C-1”), 144.8 (C-1), 155.9 (C-4), 165.7 (C-1’). HRMS (EI): m/z [M + ] calcd for C 15 H 15 NO: 225.1154; found: 225.1164 [ 51 , 99 ].…”

“…Intermolecular imine is usually synthesized by condensation reactions with an azeotropic agent [ 1 ], a desiccant [ 46 ], or a water scavenger [ 47 ] to remove water. Alkyne hydroamination arose as an alternative, being an attractive and elegant pathway with complete atom economy [ 48 , 49 , 50 , 51 ]. Barluenga et al described several catalytic and noncatalytic hydroamination methods with terminal acetylenes (e.g., 2a ) promoted by Tl(III) or Hg(II) salts [ 52 ].…”