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New chiral diphosphoramidite rhodium(I) complexes for asymmetric hydrogenation
Author(s) -
Drommi Dario,
Micalizzi Giuseppe,
Arena Carmela Grazia
Publication year - 2014
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.3170
Subject(s) - rhodium , chemistry , asymmetric hydrogenation , cationic polymerization , catalysis , chelation , cyclooctadiene , ligand (biochemistry) , nuclear magnetic resonance spectroscopy , medicinal chemistry , enantioselective synthesis , stereochemistry , polymer chemistry , organic chemistry , biochemistry , receptor
Chiral 1,5‐cyclooctadiene rhodium(I) cationic complexes with C 2 ‐symmetric chelate diphosphoramidite ligands containing ( R , R )‐1,2‐diaminocyclohexane as the backbone and two atropoisomeric biaryl units were easily synthesized and fully characterized by multinuclear one‐ and two‐dimensional NMR spectroscopy and elemental analysis. These complexes were used as catalysts in the asymmetric hydrogenation of dimethyl itaconate, methyl 2‐acetamidoacrylate and ( Z )‐methyl‐2‐acetamido‐3‐phenylacrylate. The rhodium complexes derived from diphosphoramidite ligands that contain two ( R ) or ( S ) BINOL (2,2′‐dihydroxy‐1,1′‐binaphthyl) units proved to be efficient catalysts, giving complete conversion and very good enantioselectivity (up to 88% ee). An uncommon positive H 2 pressure effect on the enantioselectivity was observed in the hydrogenation of dimethyl itaconate catalyzed by Rh‐complex with diphosphoramidite ligand that contains two ( S )‐binaphthol moieties. Copyright © 2014 John Wiley & Sons, Ltd.