The Catalytic Amination of Alcohols

Abstract

In this Minireview, the synthesis of amines by the amination of alcohols, by means of the so‐called borrowing hydrogen methodology, is presented. Compared to other synthetic methodologies for the synthesis of amines, these transformations are highly attractive because often alcohols are readily available starting materials, some of them on a large scale from renewable sources. In addition, the amination of alcohols produces water as the only by‐product, which makes the process potentially environmentally benign. Already today, lower alkyl amines are produced in bulk by the chemical industry with this synthetic method. In particular, the recent progress applying organometallic catalysts based on iridium, ruthenium, and other metals will be discussed. Notable recent achievements include the conversion of challenging substrates such as diols, the development of recyclable catalysts, milder reaction temperatures, and the direct alkylation of ammonia or its equivalents with alcohols.

Complete lignocellulose conversion with integrated catalyst recycling yielding valuable aromatics and fuels

“…6b). Amines play a central role in the chemical industry since nitrogen-containing compounds are key structural motifs in pharmaceutically active compounds, polymers or surfactants 19,20 . Surprisingly however, systematic chemo-catalytic approaches for the production of amines from lignin 29 have, to the best of our knowledge, not been realized.…”

“…Importantly, this approach delivers aromatic and aliphatic alcohols from lignocellulose, which retain part of the functionality inherent to the renewable starting material and are thus ideally suited substrates for accomplishing direct, atomeconomic transformations toward products with concrete valorization potential. Notably, among these pathways are systematic methodologies to obtain lignin-derived amines, including the highly challenging direct coupling with ammonia 19,20 , producing water as the only by-product. The overall strategy seeks to maximize sustainability in the individual reaction steps and globally through minimizing the number of reaction steps required and significantly reducing the amount of waste formed.…”

Iron catalysed direct alkylation of amines with alcohols

“…A mines are among the most valuable classes of compounds in chemistry, omnipresent in natural products, in particular alkaloids, and widely used as pharmaceuticals, agrochemicals, lubricants and surfactants [1][2][3] . Therefore the development of efficient catalytic methodologies for C-N bond formation is a paramount goal in organic chemistry 4 .…”

“…Despite recent progress, the key challenge is the development of catalysts that rely on the use of widely abundant, inexpensive metals 3,17 . Iron is considered to be the ultimate, sustainable alternative for ruthenium 18 ; however, no unequivocal reductive amination via a borrowing hydrogen mechanism has been reported 19 .…”

Direct Synthesis of Secondary Amines From Alcohols and Ammonia Catalyzed by a Ruthenium Pincer Complex

“…Later, the research groups of Vogt [15] and Beller [16] developed methods for the conversion of secondary alcohols to primary amines with ammonia. Catalytic methods for the synthesis of secondary amines starting from alcohols and amines were described by Williams [17,18], Yamaguchi [19,20], Beller [21,22], Yus [23,24] and Kempe [25,26]. Multi alkylation of ammonia to get either secondary or tertiary amines was developed by Yamaguchi, Fujita and co-workers using an iridium complex as catalyst [27,28].…”