Issue in Honor of Prof. Albert Padwa ARKIVOC 2002 (viii) 62-70
equivalent of 4 (0.200 g, 0.67 mmol), 10.0 equiv. of freshly distilled cyclopentadiene (0.444 g,
6.71 mmol), and CH2C12 (3.35 ml, 0.20 M). Purification of the crude product by flash chromatography (25% EtOAc/hexanes) gave 0.0865 g of 7 as a brown oil (50% yield). Further purification of the oil by MPLC (20% EtOAc/hexanes) gave an analytically pure sample: 1H NMR (250 MHz, CDC13): d 7.48–7.45 (m, 2H), 7.35–7.26 (m, 3H), 6.17 (br s, 2H), 4.13 (d, 1H, J = 2.0 Hz), 3.94 (d, 1H, J = 3.4 Hz), 3.55 (s, 3H), 3.13–3.10 (m, 1H), 2.99–2.97 (m, 1H), 2.20– 2.13 (m, 1H), 1.85 (d, 1H, 11.8 Hz); 13C NMR (62.9 MHz, CDC13) d 203.1, 135.2, 133.9, 132.8, 129.0, 127.4, 63.0, 59.1, 45.4, 40.0, 41.0; IR (neat) 3056w, 2952m, 2869s, 2831w, 1719s, 1584w, 1474m, 1441m, 1352w, 1312w, 1280w, 1202w, 1124s, 1048m, 1029w, 1005w, 938w, 900w, 803w, 75 m, 695m cm-1; Anal. calcd. for C15H16O2S: C, 69.20; H, 6.19. Found: C, 69.11; H, 6.39%. Acknowledgments
The authors thank the National Science Foundation and the Petroleum Research Fund, sponsored by the American Chemical Society, for support.
References
1. (a) Harmata, M. Acc. Chem. Res. 2001, 34, 595. (b) Harmata, M. Tetrahedron 1997, 53, 6235. (c) Harmata, M. Intramolecular [4+3] Cycloaddition Reactions. In Advances in Cycloaddition; Lautens, M., Ed.; JAI: Greenwich, 1997; Vol. 4, pp 41–86. (d) Rigby, J. H.; Pigge, F.C. Org. React. 1997, 51, 351. (e) Mann, J. Tetrahedron 1986, 42, 4611. (e) Hoffman, H.M.R. Angew. Chem., Intl. Ed. 1984, 23, 1. (g) Hosomi, A.; Tominaga, Y. [4+3] Cycloadditions. In Comprehensive Organic Synthesis; Trost, B. M.; Fleming, I., Eds; Pergamon: Oxford, 1991; Vol. 5, Ch. 5.1, pp 593–615. (h) Noyori, R.; Yayakawa, Y. Org. React. 1983, 29, 163. 2. Harmata, M. Heteroatom-Stabilized Allylic Cations in 4+3 Cycloaddition Reactions. In Recent Research Developments in Organic Chemistry; Transworld Research Network: Trivandrum, 1997; Vol. 1, pp. 523– 35. 3. Murray, D. H.; Albizati, K. F. Tetrahedron Lett. 1990, 31, 4109. 4. (a) Harmata, M.; Jones, D. E. J. Org. Chem. 1997, 62, 1578. (b) Harmata, M.; Jones, D.E.; Kahraman, M.; Sharma, U.; Barnes, C. L. Tetrahedron Lett. 1999, 40, 1831. (c) Harmata, M.; Jones, D. E. Tetrahedron Lett. 1997, 38, 3861. 5. (a) Stark, C. B. W.; Eggert, U.; Hoffmann, H. M. R. Angew. Chem., Int. Ed. 1998, 37, 1266. (b) Pierau, S.; Hoffmann, H. M. R. Synlett 1999, 213. (c) Roeper, S.; Frackenpohl, J.; Schrake, O.; Wartchow, R.; Hoffmann, H. M. R. Org. Lett. 2000, 2, 1661. (d) Stark, C. B. W.; Pierau, S.; Wartchow, R.; Hoffmann, H. M. R. Chem. Eur. J. 2000, 6, 684. ISSN 1424-6376 Page 69 ©ARKAT USA, Inc
