Highly efficient asymmetric Lewis acid catalysis with platinum group complexes of conformationally flexible 1,3-butadiene-bridged diphosphines, NUPHOS.
[structure: see text] Palladium and platinum complexes of conformationally flexible 1,3-butadiene-bridged diphosphines NUPHOS can be resolved with (S)-BINOL at elevated temperatures to afford diastereopure delta-[(NUPHOS)M[(S)-BINOL]] (M = Pd, Pt). The homochiral Lewis acid complexes delta-[(NUPHOS)M][OTf](2), generated by protonation of delta-[(NUPHOS)M[(S)-BINOL]] with trifluoromethanesulfonic acid, catalyze the Diels-Alder reaction between acryloyl-N-oxazolidinones and cyclopentadiene to give ee values up to 96%. The corresponding enantiopure dichlorides delta-[(NUPHOS)PtCl(2)] react with AgClO(4) to form highly efficient catalysts that give good endo/exo selectivities and high endo enantioselectivity.
Doherty
Simon
S
Centre for the Theory and Applications of Catalysis, School of Chemistry, The Queen's University of Belfast, David Keir Building, Stranmillis Road, Belfast, BT9 5AG, UK. s.doherty@qub.ac.uk
Newman
Colin R
CR
Rath
Rakesh K
RK
Luo
He-Kuan
HK
Nieuwenhuyzen
Mark
M
Knight
Julian G
JG