Catalytic Asymmetric Transfer Hydrogenation of Imines: Recent Advances

Abstract

Abstract:In this review article recent developments in the asymmetric transfer hydrogenation of imines from 2008 up today are presented. The main methodology involves either metalcatalyzed procedures in the presence of a chiral ligand or organocatalyzed technologies using a Hantzsch ester and a chiral BINOL-derived phosphoric acid. The most important procedures are collected paying special attention to the synthetic application of this methodology in synthetic organic chemistry.

Asymmetric Transfer Hydrogenation of 1‐Aryl‐3,4‐Dihydroisoquinolines Using a Cp*Ir(TsDPEN) Complex

“…Therefore, orthophosphoric acid was investigated further, including the anhydrous phosphoric acid (APA) [11] prepared by mixing the 85 % H 3 PO 4 with stoichiometric amounts of phosphorus pentoxide (Table S2, entries [16][17][18][19][20][21][22][23][24][25][26][27][28]. Interestingly, APA obtained from a commercial source gave consistently lower reactivity (Table S2, [6][7][8][9]. Interestingly, APA obtained from a commercial source gave consistently lower reactivity (Table S2, [6][7][8][9].…”

Rational Design of Simple Organocatalysts for the HSiCl3 Enantioselective Reduction of (E)-N-(1-Phenylethylidene)aniline

“…In this context, the asymmetric transfer hydrogenation of imines represents a simple and attractive approach to target the synthesis of enantiopure amines, and a variety of catalytic methodologies have been developed for this purpose [4][5][6][7][8][9][10][11][12]. The use of trichlorosilane and related reagents for this purpose has attracted much attention in recent years, having shown their capacity for the transfer hydrogenation of a variety of groups, such imines [4][5][6][7][8][9][10][11][12], enones [13,14], nitro groups [15,16], and N-heteroarenes [17,18], in the synthesis of substituted hydrazines [19], and in the reduction of CO 2 in the presence of amines [20][21][22][23]. Thus, the organocatalytic reduction of ketimines with trichlorosilane provides an efficient methodology for the asymmetric preparation of amines [24][25][26].…”

Artificial imine reductases: developments and future directions

“…28,29 Although results so far are promising, artIREDs are yet to demonstrate improved selectivity or activity compared to more established chemical reduction methods. 30,31 The range of accessible products is also limited by the stability of the imine substrates in aqueous conditions necessary for the stability of the protein scaffold. Cyclic imines tend to be stable in such conditions, but more hydrolytically labile noncyclic imines are much less so, limiting the types of amine intermediates that can be produced.…”

“…Over 80 different proteins have been used for the construction of ArMs and engineered to catalyse a huge variety of synthetic reactions, covered in a recent comprehensive review 33 and recorded in an online database (https://amp.ward-lab.ch/), produced and maintained by the Ward group. Likewise, we guide interested readers towards detailed reviews in the areas of natural IREDs 2,10,34 and synthetic organometallic imine reduction catalysts, 30,31,35 to avoid covering the same ground here. This review surveys the design of artIREDs and the and evolution strategies employed to improve their performance.…”