Enantioselective synthesis of functionalized tropanes by rhodium(II) carboxylate-catalyzed decomposition of vinyldiazomethanes in the presence of pyrroles

The assymmetric synthesis of a series of enantiomerically enriched tropanes is described. The method involves the rhodium(II) octanoate-catalyzed reaction between vinyldiazomethanes and N-BOC-protected pyrroles. The use of either (S)-lactate or (R)-pantolactone as chiral auxiliaries on the vinyldiazomethanes is found to be the most effective for pyrolles in asymmetric vinylcarbenoid transformations.