|
|
|
Journal
Publications |
|
Highly Efficient Asymmetric Lewis Acid
Catalysis with Platinum Group Complexes of Conformationally Flexible
1,3-Butadiene-Bridged Diphosphines, NUPHOS.
Simon Doherty, Colin R. Newman, Rakesh K.
Rath, He-Kuan Luo, Mark Nieuwenhuyzen and Julian G. Knight, Organic
Lett., 2003, 5, 3863. |
|
Abstract: 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 d-[(NUPHOS)M{(S)-BINOL}]
(M = Pd, Pt). The homochiral Lewis acid complexes d-[(NUPHOS)M][OTf]2,
generated by protonation of d-[(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
d-[(NUPHOS)PtCl2] react with AgClO4
to form highly efficient catalysts that give good endo/exo selectivities
and high endo enantioselectivity. |
| |
|
|
|
