D.A. Engel et al. / Tetrahedron 64 (2008) 6988e6996
6995
held at room temperature for an additional 3 h. Saturated aque-
Acknowledgements
ous NH4Cl solution was added to quench the reaction and the
mixture was extracted with ethyl acetate. The organic layer
was washed sequentially with water, saturated aqueous sodium
bicarbonate, and brine. The organic layer was dried over
MgSO4, filtered, and concentrated under reduced pressure.
To the concentrated mixture in an open flask were added
CH2Cl2 (8 mL), absolute ethanol (2 mL), and Sc(OTf)3
(2.5 mg, 0.005 mmol). After 6 h, the reaction mixture was
concentrated under reduced pressure and purified using silica
gel column chromatography (hexanes/ethyl acetate, 50:1) to
give adamantan-2-ylidene-acetic acid ethyl ester (3a) in 96%
yield over two steps (106 mg).
This research was supported by the James and Ester King
Biomedical Research Program, Florida Department of Health,
the Donors of the American Chemical Society Petroleum
Research Fund, and by the FSU Department of Chemistry
and Biochemistry. D.A.E. is the recipient of graduate fellow-
ships from FSU and the MDS Research Foundation. We are
profoundly grateful to all of these agencies for their support.
We thank Dr. Umesh Goli (FSU) for providing the mass spec-
trometry data and the Krafft Lab for the use of their FT-IR
instrument.
References and notes
4.4.1. Adamantan-2-ylidene-acetic acid ethyl ester (3a)
1H NMR (300 MHz, CDCl3) d 1.27 (t, J¼7.1 Hz, 3H), 1.86
(br s, 6H), 1.93e1.96 (m, 6H), 2.43 (br s, 1H), 4.07 (br s, 1H),
4.13 (q, J¼7.1 Hz, 2H), 5.58 (s, 1H).32
´
1. Kurti, L.; Czako, B. Strategic Applications of Named Reactions in Organic
¨
Synthesis; Elsevier: New York, NY, 2003; pp 8e9 and references cited.
2. (a) Maryanoff, B. E.; Reitz, A. B. Chem. Rev. 1989, 89, 863e927; (b)
Kelly, S. E. Alkene Synthesis; Trost, B. M., Fleming, I., Eds.; Comprehen-
sive Organic Synthesis; Pergamon: Oxford, 1991; Vol. 1, pp 729e817.
3. Trost, B. M. Science 1991, 254, 1471e1477.
4.4.2. (4,6,6-Trimethyl-bicyclo[3.1.1]hept-3-en-(2E/Z)-
ylidene)-acetic acid ester (3c)
4. Shindo, M. Synthesis 2003, 2275e2288.
5. (a) Fuks, R.; Viehe, H. G. Chem. Ber. 1970, 103, 564e572; (b) Hsung,
R. P.; Zificsak, C. A.; Wei, L.-L.; Douglas, C. J.; Xiong, H.; Mulder,
J. A. Org. Lett. 1999, 1, 1237e1240.
Title compound was prepared in a similar manner as
described above (97% yield); 1H NMR (300 MHz, CDCl3,
minor isomer) d 0.86 (s, 3H), 1.28 (t, J¼7.1 Hz, 3H), 1.40
(s, 3H), 1.68 (d, J¼7.9 Hz, 1H), 1.90 (d, J¼1.5 Hz, 3H),
2.20e2.45 (m, 1H), 2.53e2.63 (m, 2H), 4.08e4.20 (m, 2H),
6. (a) You, L.; Al-Rashid, Z. F.; Figueroa, R.; Ghosh, S. K.; Li, G.; Lu, T.;
Hsung, R. P. Synlett 2007, 1656e1662; (b) Hsung, R. P., Ed. Chemistry
of electron-deficient ynamines and ynamides (Tetrahedron Symposium-
in-Print Number 118). Tetrahedron 2006, 62, 3771e3938.
1
7. Shindo, M.; Kita, T.; Kumagai, T.; Matsumoto, K.; Shishido, K. J. Am.
Chem. Soc. 2006, 128, 1062e1063.
5.32 (s, 1H), 7.13 (s, 1H); H NMR (300 MHz, CDCl3, major
isomer) d 0.84 (s, 3H), 1.26 (t, J¼7.1 Hz, 3H), 1.44 (s, 3H),
1.58 (d, J¼8.8 Hz, 1H), 1.86 (d, J¼1.4 Hz, 3H), 2.20e2.45
(m, 1H), 2.53e2.63 (m, 2H), 4.08e4.20 (m, 2H), 5.46 (s,
1H), 5.77 (s, 1H); 13C NMR (75 MHz, CDCl3, E/Z mixture)
d 14.3, 14.4, 21.7, 21.8, 23.2, 23.6, 26.4, 26.5, 37.5, 38.1,
45.3, 47.8, 48.2, 49.0, 49.1, 53.1, 59.2, 59.3, 107.6, 110.0,
117.6, 121.6, 156.9, 158.0, 159.6, 161.2, 166.8, 167.4; IR
(neat) 2979, 2930, 2870, 1708, 1622, 1466, 1443, 1380,
1370, 1226, 1164, 1040, 874, 705 cmꢁ1; HRMS (EI) calcd
for C14H20O2 (Mþ) 220.1463. Found 220.1462.
8. (a) Meyer, K. H.; Schuster, K. Chem. Ber. 1922, 55, 819e822; (b)
Swaminathan, S.; Narayanan, K. V. Chem. Rev. 1971, 71, 429e438.
9. Examples: (a) Erman, M. B.; Aul’chenko, I. S.; Kheifits, L. A.; Dulova,
V. G.; Novikov, J. N.; Vol’pin, M. E. Tetrahedron Lett. 1976,
2981e2984; (b) Chabardes, P. Tetrahedron Lett. 1988, 29, 6253e
6256; (c) Choudary, B. M.; Durga Prasad, A.; Valli, V. L. K. Tetrahe-
dron Lett. 1990, 31, 7521e7522; (d) Narasaka, K.; Kusama, H.; Haya-
shi, Y. Chem. Lett. 1991, 1413e1416; (e) Yoshimatsu, M.; Naito, M.;
Kawahigashi, M.; Shimizu, H.; Kataoka, T. J. Org. Chem. 1995, 60,
4798e4802; (f) Lorber, C. Y.; Osborn, J. A. Tetrahedron Lett. 1996,
37, 853e856; (g) Suzuki, T.; Tokunaga, M.; Wakatsuki, Y. Tetrahedron
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10. The Rupe rearrangement (Rupe, H.; Kambli, E. Helv. Chim. Acta 1926, 9,
672).
4.4.3. (2-Isopropyl-5-methyl-cyclohexylidiene)-acetic acid
ethyl ester (3h)
The title compound was prepared in a similar manner as
R2
H
R2
R2
H+
+H2O
H+
–H2O
R1
R3
1
R1
R3
R3
described above (98% yield); H NMR (300 MHz, CDCl3,
R1
OH
O
E/Z mixture, diagnostic peaks) d 2.55 (ddd, J¼12.9, 5.5,
1.5 Hz), 3.14 (dd, J¼12.9, 4.3 Hz), 3.48e3.52 (m), 4.13 (q,
J¼7.1 Hz), 4.14 (q, J¼7.1 Hz), 5.63 (br s); 13C NMR
(75 MHz, CDCl3, E/Z mixture) d 14.3, 18.1, 19.5, 20.5,
20.8, 21.8, 23.4, 26.1, 26.8, 27.0, 27.6, 30.4, 31.6, 33.6,
33.9, 35.4, 36.1, 40.0, 43.5, 50.8, 52.6, 55.9, 59.3, 59.4,
113.3, 116.3, 164.8, 167.1.
11. Lewis Acids in Organic Synthesis; Yamamoto, H., Ed.; Wiley-VCH: New
York, NY, 2000.
12. (a) Ho, T.-L. Hard and Soft Acids and Bases Principle in Organic
Chemistry; Academic: New York, NY, 1977; (b) Chattaraj, P. K.; Lee,
H.; Parr, R. G. J. Am. Chem. Soc. 1991, 113, 1855e1856.
13. Furstner, A.; Davies, P. W. Angew. Chem., Int. Ed. 2007, 46, 3410e3449.
¨
14. For seminal examples illustrating this concept, see: Georgy, M.; Boucard,
V.; Campagne, J.-M. J. Am. Chem. Soc. 2005, 127, 14180e14181.
15. Engel, D. A.; Dudley, G. B. Org. Lett. 2006, 8, 4027e4029.
16. Examples of MeyereSchuster reactions of ethoxyalkynyl carbinols using
hard Lewis or protic acids: (a) Duraisamy, M.; Walborsky, H. M. J. Am.
Chem. Soc. 1983, 105, 3252e3264; (b) Welch, S. C.; Hagan, C. P.; White,
D. H.; Fleming, W. P.; Trotter, J. W. J. Am. Chem. Soc. 1977, 99,
549e556; (c) Crich, D.; Natarajan, S.; Crich, J. Z. Tetrahedron 1997,
53, 7139e7158.
4.4.4. Ethyl 3,3-diphenylpropenoate (3i)
The title compound was prepared in a similar manner as
1
described above (99% yield); H NMR (300 MHz, CDCl3)
d 1.11 (t, J¼7.1 Hz, 3H), 4.05 (q, J¼7.1 Hz, 2H), 6.37 (s,
1H), 7.20e7.23 (m, 2H), 7.30e7.39 (m, 8H).33