A. A. Kolomeitsev et al. / Tetrahedron Letters 49 (2008) 449–454
453
6. Taylor, S. L.; Martin, J. C. J. Org. Chem. 1987, 52, 4148–4156.
7. (a) Leroux, F.; Jeschke, P.; Schlosser, M. Chem. Rev. 2005, 105, 827–
856; and references cited therein; (b) Shimizu, M.; Hiyama, T. Angew.
Chem., Int. Ed. 2005, 44, 214–231.
8. Farnham, W. B.; Smart, B. E.; Middleton, W. J.; Calabrese, J. C.;
Dixon, W. J. J. Am. Chem. Soc. 1985, 107, 4565–4567.
9. (a) Seppelt, K. Angew. Chem., Int. Ed. 1977, 16, 322; (b) Kloeter, G.;
Seppelt, K. J. Am. Chem. Soc. 1979, 101, 347–349; (c) Christe, K. O.;
Hegge, J.; Hoge, B.; Haiges, R. Angew. Chem., Int. Ed. 2007, 46,
6155–6158.
10. Burk, P.; Koppel, I.; Rummel, A.; Trummal, A. J. Phys. Chem. A
2000, 104, 1602–1607.
11. Redwood, M. E.; Willis, C. J. Can. J. Chem. 1965, 43, 1893–
1897.
12. (a) Prakash, G. K. S.; Hu, J.; Olah, G. A. ARKIVOC 2003, 104–119;
(b) Kawashima, T.; Mori, I; Ohashi, M; Tamura, T. JP 2003081919
0046180 (to Central Glass Co.), March, 19, 2003.
13. Kolomeitsev, A. A.; Bissky, G.; Barten, J.; Kalinovich, N.; Lork, E.;
Ro¨schenthaler, G.-V. Inorg. Chem. 2002, 41, 6118–6124.
14. (a) Cheburkov, Y.; Lillquist, G. J. Fluorine Chem. 2002, 118, 123–126;
(b) Zhang, H.; Seppelt, K. Inorg. Chem. 1997, 36, 5689–
5693.
silicate (2c)13 in CH2Cl2 following the published method for 3d.8
Colorless powder, yield 98%, mp 122–124 °C (from CH3CN/ether at
ꢀ30 °C). 1H NMR (200.13 MHz, CD3CN, 20 °C): d 2.92 (s, 6H,
CH3); 3.03 (s, 6H, CH3); 3.59 (s, 4H, CH2); 13C NMR (50.32 MHz,
CD3CN, 20 °C): d 36.6 (CH3); 40.3 [(CH3)2N]; 50.1 (CH2); 164.3 (C+);
the carbon atom from CF3Oꢀ is not observed at 20 °C; 19F NMR
(188.31 MHz, CD3CN, 20 °C): d ꢀ23.7 (br s, D1/2 = 540 Hz, CF3,
3F). Anal. Calcd for C8H16F3N3O: C, 42.29; H, 7.10; N, 18.49.
Found: C, 42.41; H, 7.37; N, 18.71.
22. Ethyl-2-(trifluoromethoxy)propanoate (4-OCF3). To a cooled with
ice and magnetically stirred solution of 3b in 37 mL CH3CN,
prepared from 1 (17.6 mmol) and 2b (17.6 mmol) in situ as is
described in Ref. 20, was added in one portion 4.0 g (16.0 mmol) of
triflate 4. The temperature was raised to 20 °C within 1 h and the
mixture stirred for 2 h. The mixture was poured into sodium
hydrocarbonate solution (3%, 50 mL) and extracted with pentane
(3 ꢁ 50 mL). The combined organic extracts were washed with water
and dried over MgSO4. The final purification by distillation under
reduced pressure gave the indicated compound (3.3 g, 87.4%) as a
colorless liquid with bp 61–62 °C/ 55 Torr. 1H NMR (200.13 MHz,
3
3
CDCl3): d 1.29 (t, JHH = 7.3 Hz, 3H, CH3); 1.51 (d, JHH = 7.2 Hz,
3
3
3H, CH3); 4.24 (q, JHH = 7.3 Hz, 2H, CH2), 4.82 (q, JHH = 7.2 Hz,
1H, CH); 13C NMR (50.32 MHz, C6D6): d 14.0 (CH3), 18.5 (CH3),
15. 2,2-Difluoro-1,3-dimethylimidazolidine, DFITM (2a): Hayashi, H.;
Sonoda, H.; Fukumura, K.; Nagata, T. Chem. Commun. 2002,
1618–1619.
16. Anhydrous Me4NF: Christe, K. O.; Wilson, W. W.; Wilson, R. D.;
Bau, R.; Feng, J. J. Am. Chem. Soc. 1990, 112, 7619–7625; In this
work Me4NF was prepared by easily to scale up method disclosed in:
Kolomeitsev, A.; Seifert, F. U.; Roeschenthaler, G.-V. J. Fluorine
Chem. 1995, 71, 74–76.
3
1
61.4 (CH2), 72.6 (q, JCF = 2, 8 Hz, CH), 122.5 (q, JCF = 257.4 Hz,
CF3); 169.7 (C@O); 19F NMR (188.31 MHz, CDCl3): d ꢀ61.1 (s,
CF3). HRMS (EI) calcd for C6H9F3O3 (M+): 186.05007. Found:
186.05038.
23. Ethyl phenyl(trifluoromethoxy)acetate (5-OCF3). Triflate
generated following Effenberger‘s method.24 Triflic anhydride (1.6 g,
5.6 mmol) was added to stirred solution of (R/S) ethyl
8 was
a
17. 3i was previously synthesized on mg scale by reaction of dangerous to
handle CF3OCl with Me4N+Cl and characterized by IR/Raman
spectra: Minkwitz, R.; Broechler, R. Z. Naturforsch. B 1997, 52, 401–
404.
18. Synthesis of (CF3)2Nꢀ salts from bis(trifluoromethyl)perfluoroal-
kanesulfonamides was claimed: Hilarius, V.; Buchholz, H.; Sartori, P;
Ignatiev, N.; Kucherina, A.; Datsenko, S. WO 2000046180 (to Merck
patent G.m.b.H., Germany), August, 10, 2000.
19. (a) The all operations with the reagents 2a–i and 3a–i were performed
in oven-dried glassware under an atmosphere of dry nitrogen.
CF3SO2F was quantitatively collected in a cooled with liquid nitrogen
trap at the reduced temperature (ꢀ30 °C) and pressure (3 Torr). For
application of CF3SO2F in organic synthesis as fluorinating or
CF3SO2 transfer reagent see: Nagamori, M.; Narizuka, S. JP
2007119355 (to Central Glass Co., Ltd), May, 17, 2007; Desmarteau,
D. D.; Witz, M. J. Fluorine Chem. 1991, 52, 7–12.
hydroxy(phenyl)acetate (0.9 g, 5 mmol) in CH2Cl2 (55 mL) at
ꢀ78 °C. At the mentioned temperature the mixture was consequently
treated with 0.71 g (5.9 mmol) of 2,4,6-trimethylpyridine (collidine)
and solution of the in situ generated (similarly to Ref. 20) from 1 and
2c trifluoromethanolate 3c (2.84 g, 12.5 mmol) in CH3CN (20 mL)
and was slowly (within 6 h) warmed up till 20 °C. After aqueous
(basic) work up the crude product, contaminated with 5-F impurity,
was purified by column chromatography (hexane/ethyl acetate 10: 1)
to give the title product 5-OCF3 (0.71 g, 57%) as a colorless oil. 1H
NMR (200.13 MHz, CDCl3): d 1.26 (t, 3JHH = 7.3 Hz, 3H, CH3); 4.25
(m, 2H, CH2); 5.54 (s, 1H, CH), 7.37–7.52 (m, 5H, Ar-H); 13C NMR
3
(50.32 MHz, CDCl3): d 14.3(CH3), 62.6 (CH2), 77.4 (q, JCF = 2,
8 Hz, CH), 121.9 (q, 1JCF = 257.3 Hz, CF3); 127.5, 129.3, 130.1, 133.7
(CArH), 167.9 (C@O); 19F NMR (188.31 MHz, CDCl3): d ꢀ60.5 (s,
CF3). HRMS (EI) calcd for C11H11F3O3 (M+): 248.06603. Found:
248.06523.
20. Tris(dimethylamino)methylium trifluoromethanolate (3b). Into
a
24. Effenberger, F.; Burkard, U.; Willfahrt, J. Angew. Chem., Int. Ed.
1983, 22, 65–66.
Schlenk vessel (500 mL) containing a magnetically stirred solution
of 10.1 g (39.6 mmol) of ðMe2NÞ3CþMe3SiF (2b)13 in 75 mL of
25. Methyl 4-[(trifluoromethoxy)methyl]benzoate (6-OCF3). Yield 87%.
ꢀ
2
1
CH3CN cooled till ꢀ30 °C was condensed 8.6 g (39.6 mmol) of 1. The
Colorless liquid with bp 79–81 °C/ 0.1 Torr. H NMR (200.13 MHz,
vessel was closed and during a period of 2 h the reaction temperature
was raised from ꢀ30 °C to ambient temperature. The vessel was
cooled again till ꢀ35 °C and CF3SO2F was pumped off in vacuum
(3 Torr, for ca. 5 min) into a trap cooled with liquid nitrogen to afford
a solution of 3b in CH3CN. Then the mixture was warmed to 0 °C and
the solvent was removed in vacuo and the residue was washed with
diethyl ether (1 ꢁ 70 mL) to leave a colorless solid, which was dried in
vacuo 0.05 Torr at ꢀ30 °C for 3 h to furnish 8.9 g (98%) of 3b, purity
99.5%, mp 197–199 °C (from CH3CN/ether at ꢀ30 °C). 1H NMR
(200.13 MHz, CD3CN, 20 °C): d 2.93 (s, 18H, CH3); 13C NMR
(50.32 MHz, CD3CN, 20 °C): d 39.7 (CH3)2N]; 163.3 (C+); the carbon
atom from CF3Oꢀ is not observed at 20 °C; 19F NMR (188.31 MHz,
CD3CN, 20 °C): d ꢀ21.2 (br s, D1/2 = 370 Hz, 3F, CF3). Anal. Calcd
for C8H18F3N3O: C, 41.91; H, 7.91; N, 18.33. Found: C, 41.73; H,
8.06; N, 18.43.
CDCl3): d 3.58 (s, 3H, CH3); 4.44 (s, 2H, CH2); 6.84–6.93 (m, 2H,
Ar-H); 8.02–8.10 (m, 2H, Ar-H); 13C NMR (50.32 MHz, CDCl3): d
3
1
52.6 (ester CH3), 68.6 (q, JCF = 3.4 Hz, CH2), 122.1 (q, JCF
=
255.9 Hz, CF3), 127.8, 130.5, 131.0, 139.1 (CArH), 166.9 (C@O); 19F
NMR (188.31 MHz, CDCl3): d ꢀ60.5 (s, CF3). HRMS (EI) calcd for
C10H9F3O3 (M+): 234.05038. Found: 234.05077.
26. N-[2-(Trifluoromethoxy)ethyl]phthalimide (7-OCF3). Yield 91%
(from the triflate 7). Colorless solid with mp 77–78 °C (lit. mp 77–
77.4 °C).26 The 1H, 19F and 13C NMR data for 7-OCF3 were identical
to those found for the prepared by desulfurization–fluorination
method7 compound: Blazejewski, J.-C.; Anselmi, E.; Wakselman, C.
J. Org. Chem. 2001, 66, 1061–1063.
´
27. (a) Kolomeitsev, A. A.; Medebielle, M.; Kirsch, P.; Lork, E.;
Ro¨schenthaler, G.-V. J. Chem. Soc., Perkin Trans. 1 2000, 2183–
2185; (b) Kirsch, P.; Ro¨schenthaler G.-V.; Bissky, G.; Kolomeitsev,
A. A. DE 10254597 (to Merck patent G.m.b.H., Germany), July, 3,
2003; (c) Kolomeitsev, A. A.; Ro¨schenthaler, G.-V.; Chabanenko, K.
Yu.; Yagupolskii, Yu. L. Synthesis 1994, 145–146.
21. 2-(Dimethylamino)-1,3-dimethylimidazolidin-2-ylium trifluoromethan-
olate (3c). The compound was alternatively prepared from carbonyl-
difluoride and 2-dimethylamino-1,3-dimethylimidazolinium difluoro-