Total synthesis of tropoloisoquinolines: imerubrine, isoimerubrine, and grandirubrine. |
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Authors: | J C Lee J K Cha |
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Institution: | Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487, USA. |
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Abstract: | A unified, ready access to the tropoloisoquinoline alkaloids imerubrine (1), grandirubrine (2), and isoimerubrine (3) is delineated and features sequential application of the intramolecular Diels-Alder reaction of an acetylene-tethered oxazole and the 4 + 3] cycloaddition of an oxyallyl. A regioselective synthesis of 1 was achieved by stereo- and regioselective oxidation of an 8-oxabicyclo3.2.1]oct-6-en-3-one cycloadduct by means of the Moriarty method. Such a post-cycloaddition functionalization complements the synthetic utility of an alpha-alkoxy-substituted oxyallyl so as to broaden the scope of the oxyallyl 4 + 3] cycloaddition reaction. |
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