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Novel Chiral PNNP Ligands with a Pyrrolidine Backbone – Application in the Fe‐Catalyzed Asymmetric Transfer Hydrogenation of Ketones
Author(s) -
Mercadé Elisabet,
Zangrando Ennio,
Clotet Anna,
Claver Carmen,
Godard Cyril
Publication year - 2019
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201900778
Subject(s) - pyrrolidine , chemistry , transfer hydrogenation , catalysis , benzaldehyde , diamine , ligand (biochemistry) , medicinal chemistry , polymer chemistry , ruthenium , organic chemistry , biochemistry , receptor
The PNNP ligand ( R , R )‐{PPh 2 (2‐C 6 H 4 )CH=N(pyrrolidine‐NBn)‐} 2 2 was prepared by condensation between 2‐diphenylphosphino benzaldehyde and the pyrrolidine‐substituted diamine 1 . Reduction with NaBH 4 in MeOH afforded ( R , R )‐{PPh 2 (2‐C 6 H 4 )CH–NH(pyrrolidine‐NBn)‐} 2 3 . The corresponding iron(II) complexes [FeCl 2 ( 2 )] ( 4 ), [Fe(CH 3 CN) 2 ( 2 )](BF 4 ) 2 ( 5 ) and [Fe(CH 3 CN) 2 ( 2 )](PF 6 ) 2 ( 6 ) were synthesized and fully characterized by NMR, ESI‐HRMS, and EA. DFT calculations for complexes [FeCl 2 ( 2 )] ( 4 ) and [Fe(CH 3 CN) 2 ( 2 )](BF 4 ) 2 ( 5 ) were carried out in order to investigate the stability of related structures. The PNNP ligands 2 and 3 in combination with Fe 3 (CO) 12 as iron source were tested as catalysts in the asymmetric transfer hydrogenation of a variety of ketones with conversions higher than 95 % and enantioselectivities up to 97 %.