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

6.2.10 Preparation of (3-[1,3]Dioxalan-2-yl-allyl)trimethylsilane (69) [8]
143
Chapter Six
The title compound was prepared following the method
outlined by Gouverneur et al. [8] without modification. 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
2-vinyl-[1,3]dioxalane (0.1 cm 3 , 1 mmol), allyltrimethylsilane (0.48 cm 3 , 3 mmol) and
anhydrous DCM (3 cm 3 ). The 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 column chromatography [diethyl
ether: hexane (4:96)] afforded the product as an oil (137 mg, 74 %), (E > 90 %). δH 0.00
(9H, s, Me3Si), 1.52 (2H, dd, 3 JHH = 8.5 Hz, 4 JHH = 1.2 Hz, CH2Si), 3.86 and 3.96 (4H, 2m, -
OCH2CH2O-), 5.15 (1H, d, 3 JHH = 6.7 Hz, -OCHRO-), 5.30 (1H, ddt, 3 JHH = 15.2 Hz, 3 JHH =
6.7 Hz, 4 JHH = 1.2 Hz, Ha), 5.89 (1H, dt, 3 JHH = 15.2 Hz, 3 JHH = 8.5 Hz, Hb); δC 0.00 (CH3),
25.0 (CH2Si), 66.8 (2 x CH2), 106.6 (CHCH2), 126.6 (O2CHCH), 136.7 (O2CH).
6.2.11 Preparation of (4-Benzyloxy-but-2-enyl)-trimethylsilane (68) [8]
The title compound was prepared following the
method outlined by Gouverneur et al. [8] without
modification. 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 benzyl ether
(312 mg, cm 3 , 2.10 mmol), allyltrimethylsilane (1 cm 3 , 6.30 mmol) and anhydrous DCM (6
cm 3 ). The 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 48h. The reaction was
left to reflux for 48 h. Purification by column chromatography [diethyl ether: hexane
(3:97)] and concentration in vacuo afforded the product as an oil (141 mg , 29 %), (E/Z ratio
4:1). δH 0.02 and 0.03 (9H, 2 x s, Me3Si), 1.51 (2H, d, 3 JHH = 8.5 Hz, CH2Si), 3.96 (1.6H, d,
3 JHH = 6.4 Hz, 4 JHH = 0.9 Hz, OCH2-trans), 4.01 (0.4H, d, 3 JHH = 5.9 Hz, OCH2-cis), 4.47 and
4.50 (2H, 2 x s, -OCH2Ph), 5.46 (1H, m, Ha), 5.68 (1H, m, Hb), 7.23-7.33 (5H, m, ArH);
δC -0.21 (CH3), 24.9 (CH2Si), 73.1 (OCH2), 73.3 (CH2Ar), 125.6 (CHcisCH2Si), 126.7