Open AccessBiferrocene-Based Diphosphine Ligands: Synthesis and Application of Walphos Analogues in Asymmetric Hydrogenations
Author(s) -
Afrooz Zirakzadeh,
M. Gross,
Yaping Wang,
Kurt Mereiter,
Felix Spindler,
Walter Weissensteiner
Publication year - 2013
Publication title -
organometallics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.231
H-Index - 172
eISSN - 1520-6041
pISSN - 0276-7333
DOI - 10.1021/om3012147
Subject(s) - chemistry , ferrocene , negishi coupling , catalysis , iridium , rhodium , ruthenium , stereochemistry , combinatorial chemistry , ligand (biochemistry) , organic chemistry , electrochemistry , receptor , biochemistry , electrode
A total of four biferrocene-based Walphos-type ligands have been synthesized, structurally characterized, and tested in the rhodium-, ruthenium- and iridium-catalyzed hydrogenation of alkenes and ketones. Negishi coupling conditions allowed the biferrocene backbone of these diphosphine ligands to be built up diastereoselectively from the two nonidentical and nonracemic ferrocene fragments ( R )-1-( N , N -dimethylamino)ethylferrocene and ( S Fc )-2-bromoiodoferrocene. The molecular structures of ( S Fc )-2-bromoiodoferrocene, the coupling product, two ligands, and the two complexes ([PdCl 2 (L)] and [RuCl( p -cymene)(L)]PF 6 ) were determined by X-ray diffraction. The structural features of complexes and the catalysis results obtained with the newly synthesized biferrocene-based ligands were compared with those of the corresponding Walphos ligands.