| METHOD |
In a recent review, Reetz says a second-generation system using an eight-channel multiplexed sprayer for ionization can do up to 10,000 determinations per day. THE METHOD is ideal for kinetic resolution; that is, when the substrate is a racemate. "In the ideal case, the asymmetric catalyst will pick out only one enantiomer and transform it to product, which can be easily separated from the unreacted enantiomer," Reetz explains. It is also useful for desymmetrizing prochiral compounds into chiral products. But the method does not cover all possibilities. For example, it cannot be used in the reduction of acetophenone to (R)- or (S)-phenylethanol because the precursor cannot be labeled in such a way that the products can be differentiated. Finn's method, however, can be used for kinetic resolution and desymmetrization, as well as the ketone reduction that Reetz describes. "We take the ketone, subject it to our catalyst, and then take the reaction product and derivatize it with a mass-tagged chiral reagent," Finn explains. Accuracies are ±3% for Reetz's method and ±10% for Finn's method. As Welch says, accuracy of ±10% is good enough to separate the good catalysts from the bad ones. Reetz, however, needs greater accuracy. "In the last phases of directed evolution, when the ee has reached 90% and you want to go even higher, an assay that's ±10% is not good enough," he says |
| UPDATE | 06.02 |
| AUTHOR | Manfred T. Reetz, a chemistry professor at the Max Planck Institute for Coal Research |
| LICENSEE | Several companies are in the process of licensing this technology from us |
| LITERATURE REF. | [Angew. Chem. Int. Ed., 41, 1335 (2002)]. |
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