Nickel(II)–N<sup>Λ</sup>N<sup>Λ</sup>O Pincer Type Complex-Catalyzed N-alkylation of Amines with Alcohols via the Hydrogen Autotransfer Reaction
Gunasekaran Balamurugan, Rengan Ramesh, J.G. Małecki
Abstract
A highly sustainable catalytic protocol for the coupling of alcohols and amines for selective monoalkylated amines using Ni(II)–NΛNΛO pincer type complexes through the borrowing hydrogen methodology is described. An array of Ni(II) catalysts (1–3) was synthesized and characterized by various spectral and analytical methods. Furthermore, the distorted square planar geometry of the complexes (1 and 2) was substantiated with single crystal X-ray diffraction study. The inexpensive nickel-based catalytic methodology displays a broad substrate scope for the N-alkylation of aromatic and heteroaromatic amines using a diverse range of primary alcohols with excellent yields up to 97%. The present approach is environmentally benign, which liberates water as the sole byproduct. A short synthesis of drug intermediates such as mepyramine and chloropyramine illustrates the utility of the present protocol.