Enantioselective Conversion of Primary Alcohols to α-exo-Methylene γ-Butyrolactones via Iridium-Catalyzed C-C Bond-Forming Transfer Hydrogenation: 2-(Alkoxycarbonyl)allylation
T. Patrick Montgomery, Abbas Hassan, Boyoung Y. Park and Michael J. Krische*
*Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, United States, Email: mkrischemail.utexas.edu
T. P. Montgomery, A. Hassan, B. Y. Park, M. J. Krische, J. Am. Chem. Soc., 2012, 134, 11100-11103.
DOI: 10.1021/ja303839h (free Supporting Information)
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In the presence of a cyclometalated iridium catalyst modified by (−)-TMBTP, catalytic C-C coupling of acrylic ester with alcohols provides enantiomerically enriched 5-substituted α-exo-methylene γ-butyrolactones. Bromination of the methylene butyrolactone products followed by zinc-mediated reductive aldehyde addition provides the disubstituted α-exo-methylene γ-butyrolactones with very good levels of diastereoselectivity.
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