Nature 385, 613 - 615 (13 February 1997); doi:10.1038/385613a0

Asymmetric synthesis by enantiomer-selective activation of racemic catalysts

Koichi Mikami & Satoru Matsukawa

Department of Chemical Technology, Faculty of Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo 152, Japan

Asymmetric catalysis of organic reactions to provide enantiomerically enriched products is of central importance to modern synthetic and pharmaceutical chemistry^1–3. While non-racemic catalysts can generate non-racemic products, racemic catalysts inherently produce only a racemic mixture of chiral products. But a strategy whereby a racemic catalyst is selectively deactivated by a chiral molecule has been shown to yield non-racemic products^4–6. Here we describe an alternative, conceptually opposite strategy to asymmetric catalysis in which a chiral activator selectively activates one enantiomer of a racemic chiral catalyst. Our catalyst is a titanium(IV) complex for which a chiral additive acts as the chiral activator. The advantage of this approach over the deactivation strategy is that the activated catalyst can produce a greater enantiomeric excess in the products than can the enantiomerically pure catalyst on its own, as our results demonstrate.

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