Issue Date: July 30, 2007
Imines and CO form polypeptide mimics
Polypeptide production generally begins with the synthesis of amino acids, which are subsequently activated with stoichiometric amounts of reagents such as carbodiimides and phosgene. Chinese researchers have now developed a much easier metal-catalyzed method to make polypeptide-like compounds from inexpensive and readily available imines and carbon monoxide (Angew. Chem. Int. Ed., DOI: 10.1002/anie.200700646). Because the team used N-methylimines, the resulting polymers bear a methyl group on the nitrogens instead of the hydrogen that occupies corresponding sites in polypeptides. Chemists have been trying for years to copolymerize imines and CO but have been stymied by the lack of a suitable catalyst. Huailin Sun and colleagues at Nankai University in Tianjin, China, have now succeeded, using an acyl cobalt complex that catalyzes the reaction at 50 °C under 800 psi of CO pressure. They are currently modifying the catalyst so they can incorporate more than one type of imine in a single polymer chain.
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