Synthesis and Comparison of the Reactivity of Allyl Fluorides and ...

6.5 Experimental Details for Chapter 5
6.5.1 Preparation of 2,2-difluoro-1-phenylbut-3-en-1-ol (158)
183
Chapter Six
The title compound was prepared using a method outlined by
Audouard et al. [21] A 25 cm 3 round-bottomed flask was set up
in a sonicating bath, 3-bromo-3,3-difluoroprop-1-ene (0.07
cm 3 , 0.69 mmol), benzaldehyde (0.05 cm 3 , 0.50 mmol),
indium powder (0.05 g, 0.41 mmol) and water (7 cm 3 ) were added successively, and the
reaction mixture sonicated for 4 h at room temperature. After 4 h the reaction mixture was
quenched with HCl (10 cm 3 of a 1M aqueous solution), extracted with DCM and the
combined organic layers washed with brine (20 cm 3 ) and dried over magnesium sulphate.
After removal of solvent in vacuo the crude product was purified by column
chromatography [diethyl ether: light petroleum ether (15:85)], affording the product as a
yellow oil (49 mg, 54 %). δH 2.36-2.54 (1H, bs, OH), 4.79 (1H, ap.t, 3 JHF = 9.0 Hz, CHOH),
5.36 (1H, ddt, 3 JHH = 11.0 Hz, 4 JHF = 0.8 Hz, 2 JHH = 0.8 Hz, Hb), 5.49 (1H, ddt, 3 JHH = 17.2
Hz, 4 JHF = 2.3 Hz, 2 JHH = 0.8 Hz, Ha), 5.75 (1H, ddt, 3 JHH = 17.2 Hz, 3 JHH = 11.0 Hz, 3 JHF =
11.1 Hz, Hc), 7.22-7.34 (5H, m, ArH); δC 75.9 (t, 3 JCF = 30.2 Hz, CHOH), 119.6 (t, 1 JCF =
244.5 Hz, CF2), 121.6 (t, 3 JCF = 10.1 Hz, CHCH2), 127.7 (ArCH-3), 128.2 (ArCH-2), 128.6
(ArCH-4), 129.4 (t, 2 JCF = 25.2 Hz, CHCH2), 136.1 (ArC-1); δF -107.8 (1F, d, 2 JFF = 246.4
Hz, CF), -109.3 (1F, d, 2 JFF = 249.1 Hz, CF). m/z (EI + ) 184 ([M] + , 36 %) 107 ([M-
CF2CH=CH2] + , 100 %). HRMS (EI) 184.06960 (C10H10OF2 requires 184.06972).
6.5.2 Preparation of 2,2-difluoro-1-phenylbut-3-enyl benzoate (159)
The novel compound was prepared using a method outlined
by Nakamura et al. [7] A 100 cm 3 , two-necked round-bottomed
flask was equipped with a magnetic stirring bar, and Rotaflo
tap and attached to a Schlenk line. After flame-drying under
high vacuum, the flask was cooled and filled with nitrogen.
The reaction flask was charged with 2,2-difluoro-1-phenylbut-
3-en-1-ol (0.09 g, 0.51 mmol) and pyridine (1 cm 3 ) and cooled to 0 ºC. Benzoyl chloride
(0.065 cm 3 , 0.51 mmol) was added and the reaction mixture warmed to room temperature
and stirred for 2 h. After which the reaction was quenched with brine (6 cm 3 ) and diethyl
ether (5 cm 3 ). The organic layer was then separated and washed with HCl (1 cm 3 , 5 %
aqueous solution), saturated brine (10 cm 3 ), saturated NaHCO3 (10 cm 3 ) and saturated brine
(10 cm 3 ) successively, then dried over magnesium sulphate. After removal of solvent in