59. Enantioselective Synthesis of Functionalized Tropanes by Rhodium(II) Carboxylate-Catalyzed Decomposition of Vinyldiazomethanes in the Presence of Pyrroles

Authors: Huw M. L. Davies , Julius J. Matasi , L. Mark Hodges , Nicholas J. S. Huby , Craig Thornley , Norman Kong , and Jeffrey H. Houser

J. Org. Chem.,

1997, 62 (4), 1095–1105


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. Reactions carried out with the chiral catalyst tetrakis[N-(4-tert-butylbenzenesulfonyl)-(L)-prolinato]dirhodium (2) provided moderate asymmetric induction, but also resulted in the formation of isomeric azabicyclooctane side products. The utility of the synthetic process was demonstrated through the asymmetric synthesis of (−)-anhydroecgonine methyl ester and (−)-ferruginine.

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