A Turn for the Better

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Science  07 Jul 2000:
Vol. 289, Issue 5476, pp. 13
DOI: 10.1126/science.289.5476.13a

When inorganic chemists want to generate new ligands in order to make improved catalysts, they often turn to molecules containing phosphine groups, whose coordination to metal centers can be carefully tuned, but the design and synthesis of large ligands with multiple binding sites can be tedious.

Gilbertson et al. have modified standard resin-based peptide library synthesis by utilizing a phosphine- containing amino acid, (diphenylphosphino)serine (Pps), in addition to a D-amino acid and a proline residue that together form a β-turn motif. Libraries of hexapeptides incorporating two Pps residues were used as ligands in palladium complexes that were screened for catalysis of the asymmetric addition of dimethyl malonate to cyclopentyl acetate, a reaction for which few catalysts achieve a high enantiomeric excess (ee). Peptides that maintained the β-turn gave the highest ee's (75 to 80%), and immobilized and free complexes displayed similar catalytic activities. — PDS

J. Am. Chem. Soc., in press.

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