Kazuo Okumura

Recyclable fluorous chiral ligands and catalysts: Asymmetric addition of diethylzinc to aromatic aldehydes catalyzed by fluorous BINOL-Ti complexes

Fluorous chiral BINOLs were prepared and used as the ligands for the titanium catalyzed asymmetric addition of Et2Zn to aromatic aldehydes. Consecutive reactions were examined by utilizing fluorous–organic biphase and fluorous solid phase extraction techniques. Enantioselectivities were similar in consecutive reactions and were close to that attained in the non-fluorous system. The solid phase extraction method also enabled us to perform a simultaneous screening procedure.

Preparation of a fluorous chiral BINAP and application to an asymmetric Heck reaction

Abstract Fluorous chiral BINAP (( R )-F 13 BINAP) was prepared and was applied to an asymmetric Heck reaction. The enantioselectivity was similar in BTF homogeneous system (90% ee) to that of the original non-fluorous reaction and marginally higher in benzene and FC-72 biphasic system (93% ee) than that of the original non-fluorous one.

Enantioselective addition of diethylzinc to aldehydes catalyzed by fluorous β-aminoalcohols

Abstract A fluorous aminoalcohol prepared from ephedrine has been used as a catalyst for the enantioselective addition of diethylzinc to aldehydes to afford the corresponding alcohols in up to 84% ee. The fluorous amino alcohol was easily recovered by a simple filtration through a fluorous reverse phase silica gel and was reusable without purification.