Abstract
Optically active bis (oxazolinyl) phenyl (Phebox) was designed as an anionic N-C-N pincer ligand, and (Phebox) SnMe3 was prepared as its stable precursor. The aqua complexes, (Phebox) RhIIIX2H2O) [X=Cl, Br, F], [(Phebox) MII (H2O)] (BF4) [M=Pd, Pt] and [(Phebox) PtIV (H2O)] (BF4), were synthesized by the oxidative addition or transmetallation of RhI, PdII and PtII precursors with (Phebox) SnMe3 and subsequent ligand exchange reaction. X-ray structure studies revealed that the octahedral structure of RhIII complex is isosteric with the PtIV, and the PdII and PtII complexes are almost the same configuration with a square-planar structure. These aqua complexes acted as efficient catalysts for enantioselective allylation of aldehydes with allyltin reagents, hetero Diels-Alder reaction of Danishefsky's diene with glyoxylates and the aldol-type condensation of tosylmethyl isocyanide with aldehydes. While (Phebox) RhIII (SnMe3) Cl complexes catalyzed the Michael addition of α-cyanopropionates to acrolein.
