Organic Catalysts Get Better and Better

摘要

The ability of the amino acid proline not only to catalyze organic reactions but to favor a particular enantiomer was first noted more than 30 years ago. It excited little interest. Proline's potential was rediscovered around seven years ago, and now there is a flourishing field of so-called organocatalysis. Proline is somewhat limited as a catalyst. It is a highly polar molecule, which means it needs highly polar solvents, such as water or methanol, and clearly these limit its use by being non-compatible with reactants or reaction products. Organic chemists have sought ways to surmount this difficulty, and Steve Ley and his group in the Department of Chemistry at the University of Cambridge, have succeeded brilliantly. Their findings are reported in paper #1. This describes three types of modified proline, each with an alternative group in place of its polar carboxylic acid group. One variant has a tetrazole ring, and the other two have either a methyl, or phenyl, acyl sulfonamide group. The rationale behind these modifications was to retain an acidic proton in the group while increasing the solubility in a wider range of solvents.