Chiu-Wing Yip

ENANTIOSELECTIVE ADDITION OF DIETHYLZINC TO AROMATIC ALDEHYDES CATALYZED BY TI(BINOL) COMPLEX

Abstract The enantioselective addition of diethylzinc to aldehydes was conveniently achieved by using a catalyst prepared in situ by mixing titanium tetraisopropoxide with S - or R -binaphthol. Optical yields as high as 95.6% were obtained.

Hydrogen-bonded polymer network-poly(ethylene glycol) complexes with shape memory effect

Complexes of a poly(methacrylic acid-co-methyl methacrylate) network with poly(ethylene glycol) stabilized by hydrogen bonds were prepared. By introducing poly(ethylene glycol), the complexes possessed shape memory effect, due to which a large difference in storage modulus below and above the glass transition temperature occurred. The morphology of the complexes was investigated and the mechanism of the shape memory behavior was discussed. This kind of complexes can be regarded as a novel shape memory network.

Catalytic asymmetric addition reactions leading to carbon-carbon bond formation: Phenyl and alkenyl transfer to aldehydes and alkynylation of α-imino esters

Optically active tertiary aminonaphthol ligands were obtained by a new, convenient procedure and were found to catalyze the enantioselective alkenyl and phenyl transfer to aldehydes in high yields and excellent enantiomeric excesses (ees). The catalytic asymmetric introduction of alkynyl functionality to α-amino acid derivatives was realized by the direct addition of terminal alkynes to α-imino ester in the presence of chiral copper(I) complex under mild reaction conditions.

Enantioselective borane reduction of ketones catalyzed by chiral lanthanum alkoxides

Abstract The reaction of lanthanum triisopropoxide with chiral diols gave a highly active catalyst system for the asymmetric borane reduction of prochiral ketones.

The acceleration of the catalytic asymmetric borane reduction of ketones by organoaluminum compounds

Abstract The rates of the asymmetric borane reduction of prochiral ketones catalyzed by oxazaborolidines were found to substantially accelerate in the presence of organoaluminum compounds. The enantioselectivities of the reactions were relatively unaffected.