7258
B. Alcaide et al. / Tetrahedron Letters 45 (2004) 7255–7259
9. (a) Magnuson, S. R.; Sepp-Lorenzino, L.; Rosen, N.;
Danishefshy, S. J. J. Am. Chem. Soc. 1998, 120, 1615; (b)
Boukouvalas, J.; Cheng, Y.-X.; Robichaud, J. J. Org.
Chem. 1998, 63, 228.
skeleton in Diels–Alder reactions with different dieno-
philes are currently under investigation and fur-
ther aspects of this chemistry will be reported in due
course.
10. (a) Brownbridge, P. Synthesis 1983, 85, and references
´
cited therein; (b) Smith, A. B., III; Perez Sestelo, J.;
Dormir, P. G. J. Am. Chem. Soc. 1995, 117, 10755; (c)
Acknowledgements
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Perez Sestelo, J.; Real, M. M.; Mourin˜o, A.; Sarandeses,
L. A. Tetrahedron Lett. 1999, 40, 985.
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´
11. Alcaide, B.; Pardo, C.; Rodrıguez-Ranera, C.; Rodrıguez-
We are grateful to the DGI (MCYT-Spain) for financial
support of this research (Project BQU2003-07793-C02-
01). C.R.-R. thanks the DGI (CEC-Comunidad de
Madrid-Spain) for a predoctoral grant. R.M.M. thanks
Vicente, A. Org. Lett. 2001, 3, 4205.
12. Carbacephems are a promising new family of b-lactam
antibiotics closely related to the widely used cephalospo-
rins, with similar antibacterial profiles but with greater
chemical stability and enhanced pharmacokinetic proper-
ties. See, for example: (a) Cooper, R. D. G. In The
Chemistry of b-Lactams; Page, M. I., Ed.; Chapman and
Hall: London, 1992; Chapter 8, p 272. See, also: (b)
Folmer, J. J.; Acero, C.; Thai, D. L.; Rapoport, H. J. Org.
Chem. 1998, 63, 8170; (c) Palomo, C.; Ganboa, I.; Kot, A.;
Dembkowski, L. J. Org. Chem. 1998, 63, 6398; (d)
Ciufulini, M. A. Chem. Commun. 1996, 881; (e) Lotz, B.
T.; Miller, M. J. J. Org. Chem. 1993, 58, 618.
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the MECD for a studentship (Ôbeca de colaboracionÕ).
References and notes
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13. (a) Alcaide, B.; Almendros, P.; Rodrıguez-Salgado, N. J.
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2. For selected references, see: (a) Sandanayaka, V. P.;
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15. Representative experimental procedure for the synthesis of
2-(silyloxy)dienes 4: tert-Butyldimethylsilyl trifluorometh-
ane-sulfonate (1.2mmol) was added dropwise to a solution
of the corresponding enone 3 (1mmol) and Et3N, under
argon and cooled at 0°C in anhydrous dichloromethane
(5mL). The reaction mixture was stirred for 2h. The
mixture was washed with water, extracted with CH2Cl2,
dried over MgSO4, filtered, and concentrated under
reduced pressure. Chromatography of the residue on silica
gel deactivated with Et3N and eluting with EtOAc/hexanes
gave analytically pure compounds 4. Selected data for 2-
(silyloxy)diene (À)-4a. From 23mg (0.12mmol) of enone
(+)-3a, 36mg (100%) of compound (+)-4a was obtained as
a colorless oil. [a]D = +61.9 (c 1.0, C6H6). 1H NMR
(C6D6): 0.24 (s, 3H), 0.25 (s, 3H), 1.09 (s, 9H), 1.74 (ddt,
1H, J = 1.4, 2.4, 15.0Hz), 2.28 (m, 1H), 2.39 (m, 1H), 3.29
(s, 3H), 3.66 (dd, 1H, J = 2.3, 4.7Hz), 3.78 (dd, 1H,
J = 6.0, 12.5Hz), 4.23 (d, 1H, J = 4.7Hz), 4.33 (s, 1H),
4.39 (s, 1H), 6.48 (s, 1H). 13C NMR (C6D6): d 170.1, 155.7,
134.6, 120.7, 91.9, 85.9, 58.3, 51.7, 35.9, 26.0, 23.5, 18.4,
À4.5, À4.8. IR (CHCl3, cmÀ1): m 1741. MS (CI), m/z: 30 9
(M+, 8), 252 (M+À57, 11), 73 (100).
´
´
(c) Dıaz, N.; Suarez, D.; Merz, K. M. M., Jr. J. Am. Chem.
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3. (a) For selected references, see: Kanno, O.; Kawamoto, I.
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Tetrahedron 1999, 55, 3427; (c) Biondi, S.; Pecunioso, A.;
Busi, F.; Contini, S. A.; Donati, D.; Maffeis, M.; Pizzi, D.
A.; Rossi, L.; Rossi, T.; Sabbatine, F. M. Tetrahedron
2000, 56, 5649; (d) Ghiron, C.; Rossi, T. In The Chemistry
of Trinems in Targets in Heterocyclic Systems-Chemistry
and Properties; Attanasi, O. A., Spinelli, D., Eds.; Societa
Chimica Italiana: Rome, 1997; Vol. 1, pp 161–186.
4. For selected examples, see: (a) Page, M. I.; Laws, A. P.
Tetrahedron 2000, 56, 5631; (b) Haley, T. M.; Angier, S. J.;
Borthwick, A. D.; Singh, R.; Micetich, R. G. Drugs 2000,
3, 512; (c) Bonneau, P. R.; Hasani, F.; Plouffe, C.;
Malenfant, E.; LaPlante, S. R.; Guse, I.; Ogilvie, W. W.;
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M. M.; Cordingley, M. G.; Deziel, R. J. Am. Chem. Soc.
1999, 121, 2965; (d) Vaccaro, W. D.; Davis, H. R., Jr.
Bioorg. Med. Chem. Lett. 1998, 8, 313.
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2002, 381; (b) Alcaide, B.; Almendros, P. Chem. Soc. Rev.
2001, 30, 226; (c) Alcaide, B.; Almendros, P. Org. Prep.
Proced. Int. 2001, 33, 315; (d) Palomo, C.; Aizpurua, J.
M.; Ganboa, I.; Oiarbide, M. Synlett 2001, 1813; (e)
Palomo, C.; Aizpurua, J. M.; Ganboa, I.; Oiarbide, M.
Amino-acids 1999, 16, 321; (f) Ojima, I.; Delaloge, F.
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nonclassical structure, see: Alcaide, B.; Almendros, P.
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16. Selected data for compound 5b: Colorless oil. [a]D = +8.4
(c 0.5, C6H6). 1H NMR (C6D6): d 0.06 (s, 3H), 0.07 (s,
3H), 0.93 (s, 9H), 1.13 (ddd, 1H, J = 6.6, 12.6, 13.6Hz),
1.93 (dt, 1H, J = 4.7, 10.9Hz), 2.34 (tq, 1H, J = 2.3,
11.9Hz), 2.66 (s, 3H), 2.71 (m, 2H), 2.96 (ddd, 1H, J = 2.7,
3.5, 7.7Hz), 3.26 (s, 3H), 3.42 (s, 3H), 4.29 (d, 1H,
J = 4.8Hz), 4.67 (bd, 1H, J = 6.0Hz), 4.99 (dd, 1H,
J = 2.1, 3.5Hz), 5.12 (dd, 1H, J = 4.8, 10.7Hz). 13C
NMR (C6D6): d 177.0, 176.9, 170.1, 167.2, 153.5, 100.3,
85.1, 58.5, 52.1, 51.8, 49.6, 41.5, 38.9, 37.8, 33.7, 30.0, 25.6,
24.1, 18.2, À4.6, À5.1. IR (CHCl3, cmÀ1): m 1743, 1703.
MS (EI), m/z: 478 (M+, 2), 421 (M+À57, 19), 364
(M+À115, 45), 73 (100). (Anal. Calcd for C23H34N2O7Si:
C, 57.72; H, 7.16; N, 5.85. Found: C, 57.79; H, 7.22; N,
5.95). Compound 6b: colorless oil. [a]D = +38.5 (c 0.5,
C6H6). 1H NMR (C6D6): d 0.02 (s, 3H), 0.15 (s, 3H), 0.98
(s, 9H), 1.80(m, 1H), 2.26 (bt, 1H, J = 14.5Hz), 2.34 (t,
1H, J = 7.6Hz), 2.58 (bd, 1H, J = 16.5Hz), 2.63 (s, 3H),
2.74 (m, 2H), 3.28 (m, 1H), 3.31 (s, 3H), 3.44 (s, 3H), 4.22
7. Oppolzer, W. Intermolecular Diels–Alder Reactions. In
Comprehensive Organic Synthesis; Trost, B. M., Fleming,
I., Eds.; Pergamon: Oxford, 1991; Vol. 5, p 315.
8. Fringuelli, F.; Taticchi, A. Dienes in Diels–Alder Reaction;
Wiley: New York, 1990.