Enantioselective Total Synthesis of Macfarlandin C,a Spongian Diterpenoid Harboring a Concave-Substituted cis-Dioxabicyclo[3.3.0]octanone Fragment |
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Authors: | Dr Tyler K Allred Dr André P Dieskau Dr Peng Zhao Dr Gregory L Lackner Prof Larry E Overman |
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Institution: | Department of Chemistry, University of California, Irvine, 1102 Natural Sciences II, Irvine, CA, 92697-2025 USA |
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Abstract: | The enantioselective total synthesis of the rearranged spongian diterpenoid (−)-macfarlandin C is reported. This is the first synthesis of a rearranged spongian diterpenoid in which the bulky hydrocarbon fragment is joined via a quaternary carbon to the highly hindered concave face of the cis-2,8-dioxabicyclo3.3.0]octan-3-one moiety. The strategy involves a late-stage fragment coupling between a tertiary carbon radical and an electrophilic butenolide resulting in the stereoselective formation of vicinal quaternary and tertiary stereocenters. A stereoselective Mukaiyama hydration that orients a pendant carboxymethyl side chain cis to the bulky octahydronapthalene substituent was pivotal in fashioning the challenging concave-substituted cis-dioxabicyclo3.3.0]octanone fragment. |
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Keywords: | C-C-Kupplung Naturstoffsynthese Photoredoxchemie Radikalchemie Terpensynthese |
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