1. Doubilet, D., and Kohl, L., Natn geogr. Mag.157, (1980) 538.
2. Ayer, S.W., and Andersen, R.J., Tetrahedron Lett.10 (1982) 1039 and references therein.
3. Nybakken, J., and Ajeska, R.A., Veliger19 (1976) 19.
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5. 1H NMR (400 MHz, CDCl3), δ 1.11 (d, 7.1 Hz, 3H), 1.41 (m, 1H), 1.61 (bs, 3H), 1.70 (bs, 3H), 1.77 (m, 1H), 2.05 (m, 2H), 2.36 (m, 1H), 5.10 (m, 1H), 9.62 (d, 1.9 Hz, 1H).13C NMR (100.6 MHz, CDCl3), δ 13.3 (q), 17.7 (q), 25.4 (t), 25.7 (q), 30.7 (t), 45.9 (d), 123.5 (d), 132.7 (s), 205.0 (d). Mass-spectrum (electron impact); 140 (2.2), 125 (0.3), 82 (100), 69 (26.9), 67 (67.0), 55 (26.3), 41 (73.4).