Tetrafluorine-containing Ketones and Acetoacetates
J. Chin. Chem. Soc., Vol. 54, No. 3, 2007 755
2JH,F = 50.8 Hz), 4.35 (q, 2H, 3JH,H = 7.1 Hz), 1.35 (t, 3H,
3JH,H = 7.1 Hz); 13C NMR d 164.7 (d, 2JC,F = 26.2 Hz), 80.9
(d, 1JC,F = 262.7 Hz), 63.2, 13.9.
equal volume of concentrated H2SO4 at 40-45 °C and 35
mmHg gave 1.80 g (56%) of the titled compound. 19F NMR
d -83.3 (d, 4JF,F = 9.8 Hz), -200.7 (dq, 2JF,H = 39.8 Hz, 4JF,F
= 9.8 Hz); 1H NMR d 5.05 (d, 1H, 1JH,F = 47.7 Hz), 4.38 (q,
2H, 3JH,H = 7.1 Hz), 1.43 (t, 3H, 3JH,H = 7.1 Hz). 13C NMR d
Preparation of (i-C3H7O)2P(O)CFHCO2Et (8)
A 300 mL three-necked flask equipped with an air
condenser was charged with 0.76 moles (158 g) of freshly
distilled triisopropyl phosphite and 0.54 moles (100 g, 63
mL) of ethyl bromofluoroacetate. The contents of the flask
were heated to 145 °C for 12 h. Distillation of the reaction
mixture at 101-104 °C and 0.5 mmHg gave 101 g (71%) of
the titled phosphonate; GLPC purity: 99%; 19F NMR d
-209.6 (dd, 2JF,P = 72.3 Hz, 2JF,H = 48.2 Hz); 31P NMR d 8.5
(2JP,F = 72.3 Hz); 1H NMR d 5.40 (dd, 1H, 2JH,F = 44.0 Hz,
2JH,P = 12.0 Hz), 4.80-4.63 (m, 2H), 4.30 (q, 2H, 3JH,H = 7.3
Hz), 1.4-1.3 (m, 15H); 13C NMR d 164.9 (d, 2JC,F = 21.8
191.6 (qd, 2JC,F = 33.0 Hz, 2JC,F = 22.3 Hz), 166.4 (d, 2JC,F
=
22.3 Hz), 122.5 (q, 1JC,F = 285.0 Hz), 85.5 (d, 2JC,F = 199.0
Hz), 63.2 (s), 14.1 (s); MS m/z: 174 (M+-CH2=CH2, 41.8),
157 (M+-OEt, 9.8), 133 (M+-CF3, 13.9), 129 (M+-CO2Et,
48.2), 105 (M+-CF3C(O), 25.8), 45 (100.0). FTIR spectrum
(CC14 solution): 3418 (broad), 2973 (s), 2971 (s), 2930 (s),
2908 (m), 2882 (m), 1743 (s), 1735 (s), 1466 (m), 1299 (s),
1254 (s), 1187 (m), 1162 (m) cm-1. Anal. Calcd. for
C6H6F4O3: C, 35.65; H, 2.97. Found: C, 35.57; H, 2.94%.
Preparation of CF3C(O)CFHPh (12a)
1
1
4
Hz), 84.6 (dd, JC,F = 195.0 Hz, JC,P = 195.0 Hz), 62.3,
24.1, 23.7, 14.1; GC-MS m/z (relative intensity): 272
(M++2, 8.0), 271 (M++1, 77.0), 269 (M+-1, 2.0), 263 (0.8),
253 (0.4), 243 (100.0), 229 (11.0); FTIR spectrum (CCl4
solution): 2985 (m, C-H), 2933 (m), 1760 (s, C=O), 1279
(m, P=O), 1272 (s), 1221 (m, C-O-C), 1032 (m, P-O-C)
cm-1.
Yield: 52%; 19F NMR d -81.1 (d, JF,F = 9.4 Hz),
2
2
1
-198.2 (dq, JF,H = 48.0 Hz, JF,F = 9.4 Hz); H NMR d
7.45-7.41 (m, 2H), 7.32-7.26 (m, 3H), 5.26 (d, 1H, 1JH,F
=
48.0 Hz); MS m/z: 206 (M+, 2.5), 137 (M+-CF3, 32.8), 109
(M+-CF3C(O), 18.5), 97 (CF3C(O), 6.3), 77 (100.0), 69
(CF3, 42.3); FTIR spectrum (CC14 solution): 3308 (broad),
3048 (w), 3016 (m, Ar-H), 2973 (s), 2971 (s), 2880 (m,
C-H), 1743 (s), 1735 (s), 1466 (m), 1382 (s, C-F), 1199 (s)
cm-1. Anal. Calcd. for C9H6F4O: C, 52.43; H, 2.91. Found:
C, 52.58; H, 2.88%.
General Procedure for Preparation of
CF3C(O)CFR2R3 as Described for Preparation of
CF3C(O)CFHCO2Et (13a) from
(i-C3H7O)2P(O)CFHCO2Et (8)
Preparation of CF3C(O)CF(CH3)Ph (12b)
4
A solution of 16.0 mmoles (4.32 g) of (i-C3H7O)2-
P(O)CFHCO2Et and 30 mL of dry THF were cooled to -78
°C via a dry ice/i-PrOH slush bath under nitrogen. To the
cooled solution, 16.0 mmoles (6.4 mL) of a 2.5 M n-butyl-
lithium was added dropwise via syringe. The resultant
bright yellow solution was stirred at -78 °C for 20 min and
then 16.0 mmoles (2.97 g, 2.7 mL) of trimethylsilyl trifluo-
roacetate was added dropwise via syringe. The resultant
mixture was stirred at -78 °C for 1 h and then allowed to
warm to room temperature. Analysis of the reaction mix-
ture indicated the presence of two compounds with the fol-
lowing signals: d -75.8 ppm (s), d -71.3 ppm (d, 4JF,F = 18.3
Hz) and d -193.0 ppm (q, 4JF,F = 18.3 Hz). The signal at d
-75.8 ppm corresponds to unreactive trimethylsilyl trifluo-
roacetate, and the signals at d -71.3 ppm and d -193.0 ppm
correspond to the enolate. Treatment of the reaction mix-
ture with 2.5 mL of a 6 N HC1 solution, drying over MgSO4
and concentration on a rotary evaporator yielded a yellow
residue. Distillation of the residue in the presence of an
Yield: 50%; 19F NMR d -80.8 (d, JF,F = 10.9 Hz),
-190.2 (qq, 3JF,H = 20.2 Hz); 1H NMR d 7.39-7.33 (m, 2H),
7.28-7.21 (m, 3H), 1.46 (d, 3H, 3JH,F = 20.2 Hz); MS m/z:
222 (M++2, 8.3), 219 (M+-1, 4.2), 205 (M+-CH3, 13.5), 151
(M+-CF3, 15.2), 109 (M+-CF3C(O), 29.8), 69 (100.0). FTIR
spectrum (CC14 solution): 3151 (w), 3046 (m, Ar-H), 2984
(m), 1767 (m), 1739 (s), 1675 (m), 1652 (m), 1456 (m),
1311 (s), 1287 (s), 1118 (m), 1111 (m) cm-1. Anal. Calcd.
for C10H8F4O: C, 54.55; H, 3.64. Found: C, 54.67; H,
3.68%.
Preparation of CF3C(O)CF(CH2CH=CH2)Ph (12c)
4
Yield: 45%; 19F NMR d -80.3 (d, JF,F = 12.1 Hz),
3
4
1
-192.1 (tq, JF,H = 25.0 Hz, JF,F = 12.1 Hz); H NMR d
7.43-7.39 (m, 2H), 7.31-7.28 (m, 3H), 5.62-5.56 (m, 1H),
5.15-5.11 (m, 2H), 2.78-2.72 (m, 2H); MS m/z: 247 (M++1,
4.2), 246 (M+, 3.1), 218 (M+-CH2=CH2, 41.2), 171 (M+-CF3,
22.3), 149 (M+-CF3C(O), 31.0), 121 (M+-CH2=CH2-CF3C(O),
100.0), 69 (CF3, 11.2). FTIR spectrum (CC14 solution):