Chiral Oxazaborolidines as Catalysts for the Enantioselective Addition of Diethylzinc to Aldehydes
PURDUE UNIV LAFAYETTE IN RICHARD B WETHERILL LAB
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While the chemistry involving stoichiometric reactions of organoboranes has been amply investigated and shown to be rich and diversified, catalytic processes especially asymmetric, have been relatively neglected, and only recently have a number of enantioselective reactions catalyzed by chiral organoboranes appeared in the literature. However, since many reactions are catalyzed by Lewis acids and since chiral organoboranes are readily accessible chiral Lewis acids, we have undertaken a program to develop new catalysts based on boron and to apply them to suitable reactions. The addition of diethylzinc, DEZ, to aldehydes is one such reaction. DEZ reacts with aldehydes very sluggishly at 25 C in non-coordinating solvents. In 1984 Oguni and Omi reported that small amounts of amino alcohols greatly accelerated the reaction and induced optical activity, albeit modest, when optically active amino alcohols were involved. Organic chemistry.
- Organic Chemistry