Michael addition of nitromethane to non-racemic chiral Cr(CO)3 complexes of ethyl cinnamate derivatives: stereoselective synthesis of (R)-(-)-baclofen

We carried out a highly stereoselective Michael addition (96% de) of nitromethane to enantiomerically pure tricarbonyl(ethyl-4-chloro-2-trimethylsilylcinnamate)chromium(0). This reaction is the key step in the synthesis of (R)-(^)-baclofen, a potent antispastic drug.