Rhodium-Catalyzed Enantioselective Hydrogenation of β-Acylamino Nitroolefins: A New Approach to Chiral β-Amino Nitroalkanes

Abstract

An efficient and highly enantioselective catalytic asymmetric hydrogenation of β-acylamino nitroolefins has been realized by using Rh-TangPhos as the catalyst. A series of β-amino nitroalkane products, which are versatile intermediates in organic synthesis, were obtained with high yield and good enantioselectivity.

Synthesis and structures of copper complexes bearing unsymmetric derivatives of (R,R)‐1,2‐diaminocyclohexane: An efficient catalyst for asymmetric Henry reaction

“…[36,54,55] The 2.7239(2)-2.7239(2) Å distance between Cu1···Cl3 and Cu2···Cl1 in [L 4 CuCl 2 ] 2 suggests a weak interaction (Table 2). However, the N-Cu-N [84.20(2)-84.7(2)°], Cl1-Cu1-Cl2 [93.16 (7)°] and Cl3-Cu2-Cl4 [91.69(8)°] angles were smaller than we previously reported with C 2 -symmetric ligands. [44][45][46]54] The angles between the Cu1-C1l-Cl2 and Cu1-N1-N2 planes ranged from 6.5(2)°to 9.8(2)°.…”

“…The asymmetric Henry reaction is one of the most significant and versatile organic transformation reactions for the synthesis of β ‐nitroalcohols (Scheme ) . This reaction has received much attention in synthetic chemistry because the resulting β ‐nitroalcohols can be conveniently converted into many valuable building blocks, such as β ‐aminoalcohols, 1,2‐diamines and α‐hydroxy carboxylic acids . Although this reaction has been known for over a century, Shibasaki's and co‐workers pioneering work on its asymmetric version attracted the attention of the synthetic community.…”

“…[1] This reaction has received much attention in synthetic chemistry [2][3][4] because the resulting β-nitroalcohols can be conveniently converted into many valuable building blocks, such as β-aminoalcohols, 1,2-diamines and αhydroxy carboxylic acids. [5][6][7][8] Although this reaction has been known for over a century, [9] Shibasaki's and coworkers pioneering work [10][11][12][13][14] on its asymmetric version attracted the attention of the synthetic community. Since then, a great number of metal-based catalysts [15,16] and organocatalysts [17][18][19] have been successfully established in the development of asymmetric Henry reactions.…”

Organocatalytic Enantioselective Transfer Hydrogenation of β‐Amino Nitroolefins

“…More recently, enantioselective metal‐catalysed asymmetric hydrogenations13 of β‐acylamino nitroolefins have been developed. In 2013, Wang and Zhang used a Rh‐Tangphos complex achieving high enantioselectivities for β‐aryl β‐amino nitroalkenes (up to 93% ee ) but rather poor enantioselectivities for alkyl substrates (only 8–22% ee ) [Scheme , (i)] 14. Afterward, a highly efficient enantioselective hydrogenation of β‐acylamino nitroolefins has been successfully accomplished employing an Ir‐spiroPhos complex and 20 atm H 2 as reported by Hou15 [Scheme , (ii)] and by a rhodium/bifunctional bisphosphine‐thiourea ligands complex employing 50 atm H 2 as very recently reported by Hu, Dong and Zhang [Scheme , (iii)] 16…”

A General Catalytic Enantioselective Transfer Hydrogenation Reaction of β,β-Disubstituted Nitroalkenes Promoted by a Simple Organocatalyst

“…Concurrently, enantioselective metal-catalyzed reductions of β,β-disubstituted nitroalkenes have been developed, employing different chiral complexes based on Cu, Rh, and Ir in hydrosilylation, transfer hydrogenation, and hydrogenation reactions [9,10,11,12,13,14,15,16,17,18,19,20]. Protocols featuring very broad substrate scopes encompassing not only a variety of β-alkyl-β-aryl and β,β-dialkyl nitroalkenes 1 [9,10,11,12,13,14,15,16], but also their β-amido [17,18,19] and β-carbonyl [20] counterparts 2 – 3 are available. A Lewis base catalyzed hydrosilylation reaction with substrates 2 has also been reported [21].…”