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

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Chapter Six
reaction mixture was heated to reflux. Second generation Grubbs catalyst (5 % mol, 84 mg,
0.10 mmol) was weighed into a V-shaped dropping tube in a dry box and then transferred to
the reaction flask, addition was in three portions over 48 h. The reaction was left to reflux
for 48 h. Purification by flash column chromatography [diethyl ether: hexane (15:85)] and
concentration in vacuo afforded the product as an oil (325 mg, 65 %), (E/Z ratio 4/1). δH
0.00 and 0.02 (9H, 2 x s, Me3Si), 1.52 (1.6H, d, 3 JHH = 8.2 Hz, SiCH2-trans), 1.63 (0.4H, d,
3 JHH = 9.1 Hz, SiCH2-cis), 4.73 (1.6H, d, 3 JHH = 6.7 Hz, 4 JHH = 0.9 Hz, OCH2-trans), 4.82
(0.4H, d, 3 JHH = 7.31 Hz, OCH2-cis), 5.47-5.60 (1H, m, Ha), 5.74 (0.2H, m, Hbcis), 5.84
(0.8H, dtt, 3 JHH = 15.2 Hz, 3 JHH = 8.2 Hz, 4 JHH = 1.2 Hz, Hbtrans), 7.41 (2H, tm, 3 JHH = 7.0
Hz, ArH-3), 7.53 (1H, tm, 3 JHH = 7.31 Hz, ArH-4), 8.02 (2H, dm, 3 JHH = 8.5 Hz, ArH-2); δC
0.0 (CH3), 21.4 (CH2cisSi), 25.1 (CH2-transSi), 62.8 (OCH2-cis), 68.1 (OCH2-trans), 122.8
(CHcisCH2Si), 124.1 (CHtransCH2Si), 130.3 (ArCH-3), 132.6 (ArCH-2), 132.6 (ArC-1), 134.2
(OCH2CHcis), 134.7 (ArCH-4), 136.1 (OCH2CHtrans), 168.5 (C=O).
6.2.14 Preparation of 4-(trimethylsilyl)but-2-enyl 4-methylbenzoate (92)
The novel compound was prepared following
the method outlined by Gouverneur et al. [8] A
100 cm 3 , three-necked round-bottom flask
was equipped with a magnetic stirring bar and
condenser and attached to a Schlenk line. After flame-drying under high vacuum, the flask
was cooled and filled with argon. The flask was charged with allyl 4-methylbenzoate (430
mg, 2.44 mmol), allyltrimethylsilane (1.16 cm 3 , 7.33 mmol) and anhydrous DCM (8 cm 3 ).
The reaction mixture was heated to reflux. Second generation Grubbs catalyst (5 % mol,
110 mg, 0.10 mmol) was weighed into a V-shaped dropping tube in a dry box and then
transferred to the reaction flask, addition was in three portions over 48 h. The reaction was
left to reflux for 48 h. Purification by flash column chromatography [diethyl ether:hexane
(15:85)] and concentration in vacuo afforded the product as an oil (216 mg, 34 %), (E/Z
ratio 4/1); δH 0.00 and 0.02 (9H, 2 x s, Me3Si), 1.52 (1.6H, d, 3 JHH = 9.0, 4 JHH = 1.2 Hz,
SiCH2-trans), 1.62 (0.4H, d, 3 JHH = 9.0 Hz, 4 JHH =1.6 Hz, SiCH2-cis), 2.39 (3H, s, CH3), 4.71
(1.6H, d, 3 JHH = 7.0 Hz, 4 JHH =1.2 Hz, OCH2-trans), 4.80 (0.4H, d, 3 JHH = 7.0 Hz, 4 JHH = 1.2
Hz, OCH2-cis) 5.48-5.60 (1H, m, Ha), 5.73 (0.2H, m, Hbcis), 5.84 (0.8H, dtt, 3 JHH = 15.3 Hz,
3 JHH = 8.2 Hz, 4 JHH = 1.2 Hz, Hbtrans), 7.21 (2H, d, 3 JHH = 8.6 Hz, ArH-3) 7.91 (2H, dm, 3 JHH
= 8.2 Hz, ArH-2); δC 0.0 (CH3), 21.4 (SiCH2-cis), 23.6 (CH3), 24.9 (SiCH2-trans), 62.6
(OCH2-cis), 67.9 (OCH2-trans), 122.9 (CHcisCH2Si), 124.3 (CHtransCH2Si), 129.9 (ArC-1),
130.0 (ArCH-3), 131.6 (ArCH-2), 134.0 (OCH2CHcis), 135.9 (OCH2CHtrans), 145.4 (ArC-4),