Asymmetric Hydrogenation vs Transfer Hydrogenation in the Reduction of Cyclic Imines

Abstract

A comparison between the two most common reduction approaches for obtaining chiral amines, asymmetric hydrogenation (AH) versus asymmetric transfer hydrogenation (ATH), was accomplished by using iridium complexes based on atropoisomeric diphosphines and cyclic diamines as ligands respectively. Seven substrates, different in electronic and steric properties, were screened applying both reduction methods. For AH the best results in terms of enantioselectivity (e.e. up to 64%) were obtained by using [Ir(COD)(TetraMe‐BITIOP)]Cl in the presence of DCDMH as additive. ATH was carried out with [IrCp*(CAMPY)Cl]Cl as catalyst, allowing the obtainment of the products with appreciable e.e. (up to 76%).

Stereoselective Reducing Complexes Supported in Solid Phase: Preparation and Reactivity Study

“…These changes are attributed to the generation of secondary amine. It should be noted the repeating pattern of total fluorescence quenching in the resin containing a nitro group …”

“…It should be noted the repeating pattern of total fluorescence quenching in the resin containing a nitro group. [3,7,16]…”

“…Nowadays one of the most important challenges in organic chemistry is the preparation of new chiral molecules in enantiomerically pure forms, evaluating different ways to carry out the hydrogenation of prochiral molecules and better yet to obtain materials which can be a potential chiral catalyst . Multiple results about the synthesis of new enantiomerically pure materials that provides satisfactory results, and show high yields and enantioselectivity, have been reported.…”

An Easy Approach to Obtain Alcohol-Amines by Reduction of Alcohol Functionalized Imines

“…The reduction of imines to isolate amines is a well-known field of study. In fact, it is one of the central reactions in organic chemistry, and the search for more efficient and practical synthetic methods for carrying out this reduction is a theme of constant interest [3][4][5]. Many reduction agents have been tested in order to produce the mentioned transformation, and H2 [6], silanes [7,8], boranes [9], and borohydrides [10] are maybe the most popular ones.…”

Synthesis and crystallographic structure of nickel(0) carbonyl complex with Bitianp, an atropoisomeric diphosphine

“…Bidentate diphosphine have played a key role in several catalytic processes and have proved to be among the most active chiral ligands for stereoselective applications [1][2][3][4][5]. Atropoisomeric diphosphines [6][7][8][9], in particular, represent a class of phosphorus ligands that have been established as being extremely efficient in the asymmetric hydrogenation of a wide range of substrates, particularly aryl and heteroaryl ketones [10][11][12][13][14][15][16][17]. Whereas, Ni(0) complexes of atropoisomeric diphosphines are known for stereo-selectively catalysis of αarylation [18][19][20][21].…”