Cobalt‐Catalyzed Selective Transformation of Levulinic Acid and Amines into Pyrrolidines and Pyrrolidinones using Hydrogen

Abstract

Cobalt-catalyzed selective transformation of levulinic acid and primary amines into pyrrolidines and pyrrolidinones under H 2 has been developed. The catalyst system consisting of Co(NTf 2 ) 2 , 1,1,1-tris(di(4methoxyphenyl)phosphinomethyl) ethane ((p-anisyl)triphos) and Me 3 SiOTf works well for the synthesis of pyrrolidines via reductive amination/cyclization/deoxygenative reduction of amide, and using Co(NTf 2 ) 2 /1,1,1tris(diphenylphosphinomethyl) ethane (triphos) as the catalyst under reduced hydrogen pressure results in exclusive formation of pyrrolidinones. Both aryl and alkyl primary amines are suitable substrates, and a variety of functional groups are tolerated. Meanwhile, 4-oxo-4-arylbutanoic acids, 5-oxohexanoic acid, 6-oxoheptanoic acid, 2-formylbenzoic acid, 2-acetylbenzoic acid and 2'-acetyl-[1,1'-biphenyl]-2-carboxylic acid are also applicable, allowing for convenient access to cyclic amines and lactams with different ring size.

Reductive Amination of Levulinic Acid to Pyrrolidones: Key Step in Biomass Valorization towards Nitrogen‐Containing Chemicals

“…However, residual siloxanes were inevitably formed, leading to atomic inefficiencies and cumbersome checking procedures. Based on this, Shi et al [32] . developed a Co‐based catalyst for the reductive amination of LA and obtained surprising results (Table 1, Entry 34).…”

“…However, residual siloxanes were inevitably formed, leading to atomic inefficiencies and cumbersome checking procedures. Based on this, Shi et al [32] developed a Co-based catalyst for the reductive amination of LA and obtained surprising results (Table 1, Entry 34). Co(NTf 2 ) 2 /(p-anisyl) triphosphorus/Me 3 SiOTf catalyst efficiently produced pyrrolidones through reductive amination/ cyclization/deoxidation of amides, while the Co(NTf 2 ) 2 /triphosphorus catalyst produced pyrrolidones at a reduced hydrogen pressure.…”

Catalytic Conversion of Levulinic Acid to Pyrrolidone under Mild Conditions with Disordered Mesoporous Silica‐Supported Pt Catalyst

“…[27,28] During the past decades, various heterogeneous catalysts were developed for reductive amination processed with hydrogen. [29][30][31][32][33][34][35][36][37] The reactions with non-noble-metal based catalysts, such as Ni and Cu, always needed high temperature (> 120 °C) and high hydrogen pressure (> 3 MPa). For example, in 2022, Chen group reported Cu/Al 2 O 3 catalyzed reductive amination reaction.…”

“…Hence, hydrogen, the greenest and most atom economical reductant for the reductive amination of LA was researched [27,28] . During the past decades, various heterogeneous catalysts were developed for reductive amination processed with hydrogen [29–37] . The reactions with non‐noble‐metal based catalysts, such as Ni and Cu, always needed high temperature (>120 °C) and high hydrogen pressure (>3 MPa).…”

Calcium(II)-Catalyzed Reductive Amination of Biomass-Derived Keto Acids to Functionalized Lactams under Solvent-Free Conditions

“…5 Compared with industrial processes, the synthesis of pyrrolidones starting from biomass-derived LA by a catalytic reductive amination process is an attractive and more sustainable protocol. In this context, various heterogeneous catalytic systems have been developed for the synthesis of pyrrolidones but employing only transition metals, such as Pd, 6 Pt, 7 Cu, 8 Ru, 9 Ni, 10 Au, 11 Ir, 12 and Co. 13 Also, various homogeneous catalysts have been used for the reductive amination of LA, such as Ir, 14 Fe, 15 Co, 16 or Ru complexes, 17 In(OAc) 3 , 18 AlCl 3 , 19 B(C 6 F 5 ) 3 , 20 and ionic liquids. 21 Additionally, a handful of catalyst-free systems have been developed for the synthesis of pyrrolidones relying on a Leuckart− Wallach type mechanism under harsh reaction conditions or the use of DMSO and Et 3 N, 22 which made them less environmentally friendly (Scheme 1a).…”