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

摘要

A series of enantiomerically enriched tropanes was synthesized by the rhodium(II) octanoate- catalyzed reaction of various N-BOC-protected pyrroles with vinyldiazomethanes. The overall 3+ 4 annulation occurs by a tandem cyclopropanation/Cope rearrangement. Asymmetric induction was best achieved in these transformations by using either (S)-lactate or (R)-pantolactone as a chiral auxiliary on the vinyldiazomethanes.