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

6.2.37 Preparation of 2-chlorobut-3-enyl 4-fluorobenzoate (109)
161
Chapter Six
The novel compound was prepared following the
method outlined by Munyemana et al. [11] A 100
cm 3 , three-necked round-bottom 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 then charged with 2-hydroxybut-3-
enyl 4-fluorobenzoate (1.0 g, 4.75 mmol) and anhydrous DCM (25 cm 3 ). The flask was
then cooled to 0 ºC using an ice bath. Once cooled tetramethyl-�-chloroenamine was added
(0.64 cm 3 , 4.75 mmol) via syringe. The reaction mixture was then stirred at room
temperature for 3 h. After which purification by chromatography [DCM: cyclohexane
(50:50)] afforded the product as an oil (0.80 g, 74 %). δH 4.38 (1H, dd, 2 JHH = 11.3 Hz, 3 JHH
= 7.0 Hz, Hd), 4.42 (1H, dd, 2 JHH = 11.3 Hz, 3 JHH = 5.9 Hz, He), 4.55-4.61 (1H, m, CHCl),
5.20 (1H, ap.dt, 3 JHH = 10.2 Hz, 2 JHH = 4 JHH = 0.8 Hz, Hb), 5.35 (1H, ap.dt, 3 JHH = 16.8 Hz,
2 JHH = 4 JHH = 0.8 Hz, Ha), 5.86 (1H, ddd, 3 JHH = 16.8 Hz, 3 JHH = 10.2 Hz, 3 JHH = 7.8 Hz,
Hc), 7.05 (2H, ap.t, 3 JHH = 3 JHF = 8.6 Hz, ArH-3), 8.00 (2H, dd, 3 JHH = 9.0 Hz, 4 JHF = 5.1 Hz,
ArH-2); δC 58.7 (CHCl), 67.2 (OCH2), 115.7 (d, 2 JCF = 22.1 Hz, ArCH-3), 119.5 (CHCH2),
125.9 (d, 4 JCF = 3.0 Hz, ArC-1), 132.3 (d, 3 JCF = 10.1 Hz, ArCH-2), 134.4 (CHCH2), 165.0
(C=O), 166.0 (d, 1 JCF = 254.6 Hz, ArCF); δF -105.4 (1F, s, CF). m/z (EI + ) 228 ([M] + , 22 %)
123 ([M-OCH2CHClCH=CH2] + , 100 %). HRMS (EI) 228.03504 (C11H10O2ClF requires
228.03509).
6.2.38 Preparation of 2-chlorobut-3-enyl 3-fluorobenzoate (110)
The novel compound was prepared following the
method outlined by Munyemana et al. [11] A 100 cm 3 ,
three-necked round-bottom 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 then charged with 2-
hydroxybut-3-enyl 3-fluorobenzoate (0.2 g, 2.46 mmol) and anhydrous DCM (15 cm 3 ). The
flask was then cooled to 0 ºC using an ice bath. Once cooled tetramethyl-�-chloroenamine
was added (0.36 cm 3 , 2.71 mmol) via syringe. The reaction mixture was then stirred at room
temperature for 3 h. After which purification by chromatography [DCM: cyclohexane