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DOI: 10.1055/s-2005-871961
The First Synthesis and Reaction of β-Ethoxy-α-fluoro-α-(phenylselanyl)ethene: Scandium or Lanthanum Triflate Catalyzed α-Fluoroformylalkenylation of Aldehydes
Publication History
Publication Date:
13 July 2005 (online)
Abstract
We describe the first preparation of the hitherto unknown β-ethoxy-α-fluoro-α-(phenylselanyl)ethenes and the successful Lewis acid catalyzed α-fluoroformylalkenylation of non-enolizable aldehyde acetals to provide α,β-unsaturated aldehydes or acetals exclusively.
Key words
(phenylselanyl)ethane - scandium triflate - lanthanum triflate - double bond formation - fluorine - α,β-unsaturated aldehydes
-
1a
Welch JT. Tetrahedron 1987, 43: 3123 -
1b
Fluorine in Bioorganic Chemistry
Welch JT.Eswarakrishnan S. Wiley; New York: 1991. -
1c
Filler R.Kobayashi Y. Biomedicinal Aspects of Fluorine Chemistry Kodansha/Elsevier; Tokyo/New York: 1993. - Horner-Wadsworth-Emmons reactions:
-
2a
Sano S.Teranishi R.Nagao Y. Tetrahedron Lett. 2002, 43: 9183 -
2b
Suzuki Y.Sato M. Tetrahedron Lett. 2004, 45: 1679 -
2c
Sano S.Yokoyama K.Teranishi R.Shiro M.Nagao Y. Tetrahedron Lett. 2002, 43: 281 -
2d
Sano S.Saito K.Nagao Y. Tetrahedron Lett. 2003, 44: 3987 -
2e Zn-Cu promoted synthesis using methyl dichlorofluoroacetate:
Ishihara T.Kuroboshi M. Chem. Lett. 1987, 1145 -
2f From trifluorovinyl lithiums:
Normant JF.Foulon JP.Masure D.Sauvetre R.Villieras J. Synthesis 1975, 122 -
2g Using α-fluoro-α-organosulfinylacetate:
Chevrie D.Lequeux T.Pommelet J.-C. Tetrahedron 2002, 58: 4759 -
2h
Wong A.Welch CJ.Kuethe JT.Vazquez E.Shaimi M.Henderson D.Davies IW.Hughes DL. Org. Biomol. Chem. 2004, 168 -
3a
Liu J.Colmenarres LU.Liu RSH. Tetrahedron Lett. 1997, 38: 8495 -
3b
Andres DF.Dietrich U.Laurent EG.Marquet BS. Tetrahedron 1997, 53: 647 - 4
Sauvetre R.Masure D.Chuit C.Normant JF. Synthesis 1978, 128 - 5
Bessiere Y.Savary DN.-H.Schlosser M. Helv. Chim. Acta 1977, 60: 1739 - 6
Camps F.Coll J.Fabrias G.Guerrero A. Tetrahedron 1984, 40: 2871 -
7a
Yamakawa H.Yamashita S.Ishihara T. Synlett 1993, 353 -
7b
Yamakawa H.Odani Y.Ishihara T.Gupton JT. Tetrahedron Lett. 1998, 39: 6943 -
8a
Funabiki K.Ohtsuki T.Yamanaka H. Chem. Lett. 1994, 1075 -
8b
Funabiki K.Kurita T.Matsui M.Shibata K. Chem. Lett. 1997, 739 -
8c
Funabiki K.Ohtake C.Muramatsu H.Matsui M.Shibata K. Synlett 1996, 444 -
9a
Blanco L.Rousseau G. Bull. Soc. Chim. Fr. 1985, 455 -
9b
Patrick TB.Hosseini S.Bains S. Tetrahedron Lett. 1990, 31: 179 -
10a
Yoshimatsu M. J. Synth. Org. Chem., Jpn. 2002, 60: 847 -
10b
Vlattas I.Vecchia LD.Lee AO. J. Am. Chem. Soc. 1976, 98: 2008 -
10c
Yoshimatsu M.Oguri K.Ikeda K.Gotoh S. J. Org. Chem. 1998, 63: 4475 -
10d
Yoshimatsu M.Yamaguchi S.Matsubara Y. J. Chem. Soc., Perkin Trans. 1 2001, 2560 -
10e
Yoshimatsu M.Sugimoto T.Okada N.Kinoshita S. J. Org. Chem. 1999, 64: 5162 -
10f
Matsubara Y.Yoshimatsu M. J. Org. Chem. 2000, 65: 4456 -
10g
Yoshimatsu M.Timura Y. J. Org. Chem. 2002, 67: 5678 - 13
Ghosh S.Schlosser M. J. Fluorine Chem. 1994, 67: 53 - 14
Shi G.-q.Schlosser M. Tetrahedron 1993, 49: 1445 - 15
Andres DF.Laurent EG.Marquet BS. Tetrahedron Lett. 1997, 38: 1049 - 16
Thornberry NA.Bull HG.Taub D.Greenlee WJ.Patchett AA.Cordes EH. J. Am. Chem. Soc. 1987, 109: 7543
References
Preparation of β-ethoxy-α-fluoro-α-(phenylselanyl)ethene(4). To a toluene (80 mL) solution of ethyl 2-fluoro-2-(phenylselanyl)acetate (1; 4.00 g, 15.3 mmol) was added DIBAL-H (18.4 mL, 1 M toluene solution, 18.4 mmol) at -78 °C under an Ar atmosphere. After the reaction mixture was stirred for 30 min, 1 M HCl solution (16 mL) was added to the mixture. The resulting mixture was stirred for 10 min and then poured into H2O (200 mL). The organic layer was separated and the aqueous layer was extracted with Et2O. The combined organic layer was dried over MgSO4. The solvent was removed under reduced pressure. To the residue in EtOH (23 mL) was added ethyl orthoformate (11.4 g, 76.6 mmol) and p-TsOH (0.26 g, 1.53 mmol). The mixture was stirred for 12 h at 20 °C and poured into a sat. soln of NaHCO3 (200 mL). Work-up and purification by column chromatography on silica gel eluting with EtOAc-hexane (1:50) gave 2-fluoro-2-(phenylselanyl)acetaldehyde diethyl acetal(3) (14.1 g, 91%) as a yellow oil. IR: 2978, 2929, 2884, 2362, 2344, 1579, 1478, 1372, 1340, 1301, 1118, 1067, 1023, 999, 891, 741, 691, 470 cm-1; 1H NMR: δ = 1.25 (3 H, t, J = 7 Hz, Me), 1.26 (3 H, t, J = 7 Hz, Me), 3.62-3.68 (2 H, m, OCH2), 3.76-3.82 (2 H, m, OCH2), 4.71 (1 H, dd, J = 4, 9 Hz, acetal H), 6.02 (1 H, dd, J = 4, 52 Hz, CHF), 7.24-7.33 (3 H, m, ArH), 7.64-7.66 (2 H, m, ArH); 19F NMR (referenced to CF3CO2H): δ = -87.05 (dd, J = 9, 53 Hz); MS: m/z = 292 (M+). Anal. Calcd for C12H17FO2Se: C, 49.49; H, 5.88. Found: C, 49.27; H, 5.79
An ethereal (5.0 mL) solution of 3 (3.0 g, 10.3 mmol)was added to lithium isopropylcyclohexylamide (prepared from isopropylcyclohexylamine (2.90 g, 20.6 mmol) and BuLi (6.0 mL, 15.4 mmol) in Et2O (60 mL)) at -60 °C. The reaction mixture was warmed to -40 °C and then stirred for 10 min. The mixture was poured into H2O (200 mL). The organic layer was separated and the aqueous layer was extracted with Et2O. The combined organic layers were dried over MgSO4. The solvent was removed under reduced pressure. The residue was purified by flash chromatography on silica gel eluting with EtOAc-hexane (1:100) to give 4 (2.02 g, 80%) as a yellow oil. IR: 3444, 2980, 2357, 1658, 1577, 1477, 1439, 1395, 1313, 1194, 1130, 1061, 1000, 902, 737, 689, 535, 515, 466, 441, 425, 406 cm-1; 1H NMR: δ = 1.33 (3 H, t, J = 7 Hz, Me), 3.97 (2 H, q, J = 7 Hz, OCH2), 6.24 (1 H, d, J = 19 Hz, olefinic H), 7.24-7.30 (3 H, m, ArH), 7.48 (2 H, d, J = 8 Hz, ArH); 19F NMR: δ = -39.67 (d, J = 18 Hz); MS: m/z = 246 (weak M+). Compound 4 was too volatile to measure the elemental analysis.
A typical procedure for the preparation of 2-fluoro-4′-methoxycinnamaldehyde dimethyl acetal(6a): Lanthanum triflate (60 mg, 0.10 mmol) was added to a ClCH2CH2Cl (5.0 mL) solution of 4 (0.50 g, 2.04 mmol) and p-methoxybenz-aldehyde dimethyl acetal (0.80 g, 4.07 mmol) under an Ar atmosphere. The reaction mixture was refluxed for 10 min, cooled, and treated with Et3N (2 drops). Work-up afforded 2-fluoro-4′-methoxycinnamaldehyde dimethyl acetal (6a, 0.77 g, 85%).