Synthesis of Primary Amines:  First Homogeneously Catalyzed Reductive Amination with Ammonia

Abstract

[reaction: see text] The synthesis of primary amines via reductive amination of the corresponding carbonyl compounds with aqueous ammonia is achieved for the first time with soluble transition metal complexes. Up to an 86% yield and a 97% selectivity for benzylamines were obtained in the case of various benzaldehydes by using a Rh-catalyst together with water-soluble phosphine and ammonium acetate. In the case of aliphatic aldehydes, a bimetallic catalyst based on Rh/Ir gave improved results.

Two Iron Catalysts are Better than One: A General and Convenient Reduction of Aromatic and Aliphatic Primary Amides

“…Owing to their importance, the development of novel methods for the synthesis of primary amines continues to be an active area of research. [2] The most common approaches for their synthesis include reduction of nitriles, [3] reductive amination of aldehydes and ketones, [4] reduction of carboxylic acids in the presence of ammonia, [5] alkylation of organic halides with ammonia or ammonia equivalents, [6] borrowing hydrogenation methodologies, [7] and hydroamination of alkynes. [8] In addition to all these achievements, the selective reduction of primary amides represents a straightforward route to this class of compounds because of the availability of carboxylic acid amides.…”

Selective Synthesis of Primary Amines Directly from Alcohols and Ammonia

“…[10] Amines are also prepared by the reduction of amides, generally under harsh conditions to result in a mixture of products. [11] Iridium-and rhodium-catalyzed preparation of amines from the corresponding aldehydes under hydrogen pressure was also reported, [12] demonstrating homogeneous catalytic reductive amination with ammonia. Lewis acid catalyzed reductive amination methods for the synthesis of amines are also known.…”

Heterogeneous Ru-Based Catalysts for One-Pot Synthesis of Primary Amines from Aldehydes and Ammonia

“…Since the first catalyzed amination of aldehydes or ketones using NH3 and H2 with Ni catalyst was reported by Mignonac in 1919 [19], both homogeneous and heterogeneous catalysts were used for the direct reductive amination of carbonyl compounds [20][21][22][23][24][25][26][27][28][29][30]. For example, the reductive amination of aliphatic and aromatic ketones catalyzed by homogeneous Ir and Rh complexes was presented in the patent literature [20], but the selectivity of a primary amine was poor and the reaction conditions were strictly rigorous.…”

“…Although high selectivity and yield towards aromatic primary amines was achieved, high pressures and temperatures were required (135 °C, 65 bar H2). Moreover, the yields of the aliphatic primary amines from aliphatic aldehydes were still poor under similar reaction condition [21]. Recently, homogeneous methods were reported to prepare primary amines from ketones with reductants such as ammonium formate [22,23], silane [24,25], NaBH4 [26], the Hantzsch ester [27], NaBH3CN [28], nBu3SnH [29], and Zn(BH4)2 [30] instead of hydrogen.…”