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Zinc Complexes of β ‐Ketoiminato Ligands as Efficient Catalysts for the Synthesis of α‐Amino Nitriles via Strecker Reaction
Author(s) -
Das Suman,
Kumar Ravi,
Devadkar Ajitrao,
Panda Tarun K.
Publication year - 2020
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.202000278
Subject(s) - chemistry , zinc , homoleptic , trimethylsilyl cyanide , catalysis , medicinal chemistry , strecker amino acid synthesis , aldehyde , ligand (biochemistry) , stereochemistry , organic chemistry , enantioselective synthesis , metal , biochemistry , receptor
We report the synthesis of α‐aminonitriles by one‐pot coupling reaction of aldehyde, amines and trimethylsilyl cyanide (TMSCN) using β ‐ketoiminato zinc complexes as a pre‐catalyst in very good yield under mild reaction condition. Homoleptic zinc complex [{ κ 2 ‐(2,4,6‐Me 3 C 6 H 2 NC(Me)=CHC(Me)=O)} 2 Zn] ( 1 a ) was synthesized by the treatment of protic ligand [(2,4,6‐Me 3 C 6 H 2 NHC(Me)=CHC(Me)=O)] ( L 1 H ) with potassium hydride and anhydrous zinc diiodide in 2 : 2 : 1 molar ratio in THF. Analogous reactions using [(2,6‐ i Pr 2 C 6 H 3 NHC(Me)=CHC(Me)=O)] ( L 2 H ) and [(Ph 2 CHNHC(Me)=CHC(Me)=O)] ( L 3 H ) as protic ligands, dinuclear zinc complexes [{ κ 3 ‐(2,6‐ i Pr 2 C 6 H 3 NC(Me)=CHC(Me)=O)}ZnI] 2 ( 1 b ) and [Zn(Ph 2 CHNHC−(Me)=CHC(Me)=O)ZnI 2 ] ( 1 c ) were obtained in good yield. Molecular structures of ligands L 1 H , L 3 H , and zinc complexes 1 a , 1 b , and 1 c were established by single‐crystal x‐ray diffraction analysis. Dinuclear zinc complexes 1 b , and 1 c exhibited high transformation, greater selectivity and broad substrate scope for the synthesis of α‐aminonitrile under mild condition. A most plausible mechanism for synthesis α‐aminonitrile is proposed based on several controlled reactions.