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We describe our efforts toward the total synthesis of the natural product elisabethin A. The first route was guided by the proposed biosynthesis, assembling the 6,6-ring system before forming the five-membered ring including the quaternary carbon. The second approach includes a high yielding cyclization under Mitsunobu conditions as a key step. It allowed the preparation of an unusual and highly functionalized bicyclic 6,5-spiro compound. Both routes share a common advanced precursor obtained from an “underdeveloped” Claisen rearrangement of an aryl dienyl ether.

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The two substituted 1,2,3,4-tetrahydronaphthalenes, methyl (R)-3-{(1R,4S)-6-methoxy-4,7-dimethyl-5,8-bis[(triisopropylsilyl)oxy]-1,2,3,4-tetrahydronaphthalen-1-yl}butanoate, C36H66O5Si2, (2), and methyl (E)-3-{(1R,4S)-8-hydroxy-6-methoxy-4,7-dimethyl-5-[(triisopropylsilyl)oxy]-1,2,3,4-tetrahydronaphthalen-1-yl}acrylate, C26H42O5Si, (8), crystallize in the Sohncke space groups P212121 and P21, respectively, with the absolute structure determined on the basis of anomalous dispersion effects. The configurations of the stereo centres in the 1,2,3,4-tetrahydronaphthalene moiety of (2) and (8) are the same, and the conformation of the non-aromatic part of the ring system is nearly identical. In the crystal of (2), weak non-classical C—H...O interactions consolidate the packing, whereas in (8), intermolecular O—H...O hydrogen-bonding interactions of medium-to-weak strength direct the molecules into Z-shaped strands extending parallel to [010].