A second-generation total synthesis of (+)-phorboxazole A. |
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| Authors: | Amos B Smith Thomas M Razler Jeffrey P Ciavarri Tomoyasu Hirose Tomoyasu Ishikawa Regina M Meis |
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| Institution: | Department of Chemistry, The Penn Center for Molecular Discovery, and Monell Chemical Senses Center, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA. smithab@sas.upenn.edu |
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| Abstract: | A highly convergent second-generation synthesis of (+)-phorboxazole A has been achieved. Highlights of the synthetic approach include improved Petasis-Ferrier union/rearrangement conditions on a scale to assemble multigram quantities of the C(11-15) and C(22-26) cis-tetrahydropyrans inscribed with the phorboxazole architecture, a convenient method to prepare E- and Z-vinyl bromides from TMS-protected alkynes utilizing radical isomerization of Z-vinylsilanes, and a convergent late-stage Stille union to couple a fully elaborated C(1-28) macrocyclic iodide with a C(29-46) oxazole stannane side chain to establish the complete phorboxazole skeleton. The synthesis, achieved with a longest linear sequence of 24 steps, proceeded in 4.6% overall yield. |
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