L. Zoute et al. / Tetrahedron Letters 47 (2006) 7931–7933
7933
2002, 102, 3345–3384; (c) Charette, A. B.; Boezio, A. A.;
Janes, M. K. Org. Lett. 2000, 2, 3777–3779; (d) Charette, A.
B.; Boezio, A. A.; Janes, M. K. J. Org. Chem. 2001, 66,
2178–2180.
2 mL) under argon. The reaction was then stirred at room
temperature for 10 min and then the appropriate aldehyde
or ketone (0.5 mmol, 1 equiv) was rapidly added. The
reaction mixture was then stirred for 10 min. The resulting
solution was then quenched with ethanol (5 mL) and the
solution was concentrated under reduced pressure. The
residue was diluted with dichloromethane (2 mL) and
filtered on a small pad of celite to remove zinc salts.
Diethylether (25 mL) was then added to the filtrate that
induced the precipitation of the phosphonium salt. The
mixture was filtered on a pad of celite. The organic phase
was concentrated in vacuo to afford the nearly pure
compound. A quick flash chromatography on silica gel
(10% ethylacetate/cyclohexane) gave the expected a-fluoro
a,b-unsaturated ester. Rf = 0.5 (cyclohexane–EtOAc, 9:1).
(Z) and (E) 3-pentyl-2-fluoroacrylic acid ester: 60/40 (2d):
1H NMR (300 MHz, CDCl3): d = 6.05 (dt, 3JH–H = 8.0 Hz,
3. (a) Song, C. E.; Lee, S.-G. Chem. Rev. 2002, 102, 3495–
3524; (b) Lu, Z.-L. L.; Lindner, E.; Mayer, H. A. Chem.
Rev. 2002, 102, 3543–3578.
4. (a) Audic, N.; Clavier, H.; Mauduit, M.; Guillemin, J.-C. J.
Am. Chem. Soc. 2003, 125, 9248–9249; (b) Kim, D. W.; Chi,
D. Y. Angew. Chem., Int. Ed. 2004, 43, 483–485.
5. (a) Nakamura, H.; Linclau, B.; Curran, D. P. J. Am. Chem.
Soc. 2001, 123, 10119–10120; (b) Zhang, W. Chem. Rev.
2004, 104, 2531–2556.
6. Poupon, J.-C.; Boezio, A. A.; Charette, A. B. Angew.
Chem., Int. Ed. 2006, 45, 1415–1420.
7. (a) Zoute, L.; Dutheuil, G.; Quirion, J.-C.; Jubault, P.;
Pannecoucke, X. Synthesis, in press; For previous methods
for the synthesis of a-fluoro-a,b-unsaturated esters, see: (b)
Burton, D. J.; Yang, Z.; Qiu, W. Chem. Rev. 1996, 96, 1641;
(c) Barma, D. K.; Kundu, A.; Zhang, H.; Mioskowski, C.;
Falck, J. R. J. Am. Chem. Soc. 2003, 125, 3218–3219; (d)
Ishihara, T.; Shintani, A.; Yamanaka, H. Tetrahedron Lett.
1998, 39, 4865–4868; (e) Sano, S.; Yokohama, K.; Tera-
shini, R.; Shiro, M.; Nagao, Y. Tetrahedron Lett. 2002, 43,
281–284; (f) Sano, S.; Saito, K.; Nagao, Y. Tetrahedron
Lett. 2003, 44, 3987–3990; (g) Suzuki, Y.; Saro, M.
Tetrahedron Lett. 2004, 45, 1679–1681.
3
3JH–F = 33.3 Hz, 0.6H, H3Z), 5.85 (dt, JH–H = 8.3 Hz,
3JH–F = 21.6 Hz, 0.4H, H3E), 4.20–4.10 (m, 2H, H9), 2.40
(dq, J = 1.7 Hz, J = 8.6 Hz, 0.8H, H4E), 2.15 (dq, J =
2.2 Hz, J = 7.2 Hz, 1.2H, H4Z), 1.40–1.20 (m, 9H, H5,6,7,8),
0.83 (t, 3H, J = 6.8 Hz, H10). 13C NMR (75.5 MHz,
CDCl3): d = 161.1 (d, J = 36 Hz), 161.0 (d, J = 26 Hz),
148.0 (d, J = 255 Hz), 147.0 (d, J = 250 Hz), 123.8 (d,
J = 18 Hz), 121.0 (d, J = 12 Hz), 61.5, 61.3, 31.4, 29.0
(d, J = 2 Hz), 29.0 (d, J = 2 Hz), 25.5 (d, J = 5 Hz), 24.2 (d,
J = 2 Hz), 22.5, 22.4, 14.1, 14.0. 19F NMR (282.5 MHz,
CDCl3): d = À123.2 (d, J = 21.5 Hz, 0.4F), À131.6 (d,
J = 33.3 Hz, 0.6F). IR (neat): 2960, 2932, 1732, 1678, 1467,
1373, 1309, 1261, 1201, 1148, 1089, 765 cmÀ1. MS (EI):
m/z = 188 (M+), 91, 41.
8. General procedure: To a solution of SCG-PPh3 1 (2 mmol
4 equiv, 1.2 g) and ethyl dibromofluoroacetate (1 mmol,
2 equiv, 140 lL) in dichoromethane (5 mL) was rapidly
added diethylzinc (1 M solution in hexane, 2 mmol, 2 equiv,