Polypropionates via asymmetric catalysis

The ability to use different catalysts to obtain complementary stereochemical outcomes in the catalytic asymmetric synthesis of polypropionates has been demonstrated by Scott G. Nelson and coworkers of the University of Pittsburgh (J. Am. Chem. Soc. 2006, 128, 7438). The researchers developed the alkaloid-catalyzed acyl halide-aldehyde cyclocondensation reaction several years ago. They have now extended its applicability to the catalytic asymmetric synthesis of repeating propionate units, which are commonly found in polyketides and other natural products. They demonstrated the reaction's potential by using it to carry out the catalytic asymmetric synthesis of (-)-pironetin (shown), a polyketide with immunosuppressive and anticancer activities. "There are very few reactions in asymmetric catalysis that are effective enough to allow use in the synthesis of stereochemically complex targets," says Eric N. Jacobsen of Harvard University of the polypropionate reaction.