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Synfacts 2007(4): 0389-0389  
DOI: 10.1055/s-2007-968356
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

Ring Opening of a meso-Azabicyclic Alkene with an Arylboronic Acid

Contributor(s):Hisashi Yamamoto, Matthew B. Boxer
H. A. McManus, M. J. Fleming, M. Lautens*
University of Toronto, Canada
Enantioselective Total Synthesis of (+)-Homochelidonine by a PdII-Catalyzed Asymmetric Ring-Opening Reaction of a meso-Azabicyclic Alkene with an Aryl Boronic Acid
Angew. Chem. Int. Ed.  2007,  46:  433-436  
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Publication History

Publication Date:
23 March 2007 (online)

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Key words

palladium - asymmetric ring opening - arylboronic acids

Significance

The first enantioselective total synthesis of the biologically important (+)-homochelidonine was accomplished utilizing an excellent desymmetrization of a meso-bicylic alkene based on a palladium-catalyzed ring-opening reaction. This method creates two contiguous syn stereocenters from readily available meso compounds. Once this chirality is installed, subsequent diastereoselective bromohydrin formation leading to an epoxide is expertly accomplished.

Comment

The Lautens group has further utilized their ring-opening reactions to include an asymmetric variant for the addition of arylboronic acid nucleophiles. While they had previously reported the racemic version of this reaction (M. Lautens, C. Dockendorff Org. Lett. 2003, 5, 3695-3698) they show here that (S)-BINAP is a good ligand for this transformation. Importantly, arylboronic acids are now added to the list of nucleophiles suitable for this type of ring-opening reaction.

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