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(4‐methoxyphenyl)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 /1,1,1‐tris(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. magnified image