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Explorations in Organic Chemistry Leading to the Total Synthesis of (±)-Gelsemine

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journal contribution
posted on 27.07.2002, 00:00 by Fay W. Ng, Hong Lin, Samuel J. Danishefsky
The total synthesis of (±)-gelsemine (1) is described. A defining phase of the effort involved recourse to a strategic oxetane ring (see compound 25). It was constructed anticipating an intramolecular displacement of the carbon (C17)−oxygen (O4) bond (see product 48). A key intermediate in the stereospecific elaboration of the oxetane linkage was enone 22, which was susceptible to two β-face attacks leading to 24 and, thence, 25. Three sigmatropic rearrangements were employed in building the bridgehead (C20) and the spiroanilide (C7) quaternary centers en route to gelsemine.