DISTINCTION BETWEEN ELECTROPHILIC AND ELECTRON TRANSFER REACTIONS
23
basic alumina and placed on top of 50 g of basic alumina.
The product was flashed off the column using hexane –
EtOAc (9:1). After solvent removal, 14.3 g (84.7%) of 4-
bromothioanisole was isolated. GC analysis of the crude
product showed it was 93% pure and it was used without
(M H) (base), 147, 133, 123, 107, 91; HRMS, m/z
calculated for C11H15O 163.1123; found 163.1130.
3,5-Dimethylphenyl propenyl ether. Found to be 94%
pure by GC: b.p. 59–60°C at 1 Torr; 1H NMR, ꢂ 1.68 (dd,
3H), 2.2 (s, 6H), 4.7 (m, 1H), 6.3 (m, 1H), 6.5 (s, 3H); 13C
NMR, ꢂ 9.4, 21.3, 106.7, 114.0, 124.2, 139.3, 141.3,
157.7; LRMS, m/z 162 (base), 147, 123; HRMS, m/z
calculated for C11H15O 163.1123; found 163.1128.
further purification: LRMS, m/z 204 (M ), 202 (M ,
base), 158, 156, 108.
Then, using the above procedure, the Grignard reagent
from 4-bromothioanisole (14.3 g) and Mg (4.24 g) was
added to 8.13 g of 2-chloroethyl thiocyanate in 20 ml of
THF. The elimination was carried out with 35 g of
KOtBu in 100 ml of THF. Distillation gave 6.62 g
(55.6%) of product determined to be 92.5% pure by GC:
b.p. 100–110°C at 1.5 Torr; 1H NMR, ꢂ 2.4 (s, 3H), 5.25
(m, 2H), 6.45 (dd, 1H), 7.11 (d, 2H), 7.25 (d, 2H); 13C
NMR, ꢂ 15.8, 114.9, 127.2, 130.1, 131.7, 132.3, 138.3;
3-Methoxylphenyl propenyl ether. Found to be 96%
pure by GC: b.p. 52–53°C at 2 Torr; 1H NMR, ꢂ 1.7 (dd,
3H), 3.66 (s, 3H), 4.8 (m, 1H), 6.3 (m, 1H), 6.5 (m, 3H),
7.1 (m, 1H); 13C NMR, ꢂ 9.4, 55.1, 102.5, 107.4, 108.3,
130.1, 140.9, 158.8, 161.1.1; LRMS, m/z 164 (base), 149,
135, 125; HRMS, m/z calculated for C10H13O2 165.0916;
found 165.0914.
LRMS, m/z 182 (M ), 167, 135 (base), 123, 108, 91;
HRMS, m/z calculated for C9H11S2 (MH) 183.0302;
found 183.0296; EpOX = 1.104 V.
4-Methoxylphenyl propenyl ether. Found to be 97%
pure by GC: b.p. 54–56°C at 2 Torr; 1H NMR, ꢂ 1.7 (dd,
3H), 3.6 (s, 3H), 4.7 (m, 1H), 6.2 (m, 1H), 6.7 (m, 3H),
7.1 (t, 1H); 13C NMR, ꢂ 9.4, 55.4, 106.0, 114.7, 117.4,
142.1, 151.8, 155.2; LRMS, m/z 164 (base); HRMS, m/z
calculated for C10H13O2 165.0916; found 165.0907.
Synthesis and characterization of aryl cis-propenyl
ethers. The latter substrates were prepared by the base
(potassium tert-butoxide–DMSO) catalyzed isomeriza-
tion of appropriate allyl aryl ethers.12 The corresponding
allyl ethers were obtained by reaction of the appropriate
sodium aryloxide with allyl bromide in refluxing in
ethanol. The crude allyl aryl ethers were isomerized
without further purification.
3-Methylphenyl propenyl ether. Found to be 95% pure
by GC: b.p. 43–45°C at 2 Torr; 1H NMR, ꢂ 1.7 (dd, 3H),
2.25 (s, 3H), 4.78 (m, 1H), 6.3 (m, 1H), 6.7 (m, 3H), 7.1
(t, 1H); 13C NMR, ꢂ 9.4, 21.3, 106.9, 113.2, 117.0, 123.2,
129.3, 139.6, 141.1. 157.7; LRMS, m/z 149 (M H)
(base), 133, 121, 109, 57; HRMS, m/z calculated for
C10H13O 149.0966; found 149.0961.
Phenyl propenyl ether. Found to be 95% pure by GC:
b.p. 25–26°C at 1 Torr; 1H NMR, ꢂ 1.7 (dd, 3H), 4.8 (m,
1H), 6.3 (m, 1H), 6.9 (m, 3H), 7.2 (m, 2H); 13C NMR, ꢂ
9.2, 107.1, 116.0, 122.2, 129.4, 140.8, 157.5; LRMS, m/z
135 (M H) (base), 119, 105, 95; HRMS, m/z calculated
for C9H11O 135.0810; found 183.0819.
4-Methylphenyl propenyl ether. Found to be 96% pure
by GC: b.p. 40–42°C at 1 Torr; 1H NMR, ꢂ 1.7 (dd, 3H),
2.2 (s, 3H), 47 (m, 1H), 6.3 (m, 1H), 6.8 (d, 2H);
13C NMR, ꢂ 9.4, 20.5, 106.5, 116.1, 130.1, 131.6, 141.5,
155.7; LRMS, m/z 148 (base), 133, 119, 107; HRMS, m/z
calculated for C11H13O 149.0966; found 149.0961.
4-Bromophenyl propenyl ether. Found to be 96% pure
1
by GC: b.p. 72–74°C at 0.3 Torr; H NMR, ꢂ 1.67 (dd,
3H), 4.8 (m, 1H), 6.2 (m, 1H), 6.7 (m, 2H), 7.3 (m, 2H);
13C NMR, ꢂ 9.4, 108.1, 114.7, 117.7, 132.3, 140.3,
156.5; LRMS, m/z 213 (M H) (base), 162, 134; HRMS,
m/z calculated for C9H11OBr 212.9915; found 212.9910.
4-Biphenyl propenyl ether. Found to be 99% pure by
GC: m.p. 80–81°C (recrystallized from hexane); 1H
NMR, ꢂ 1.7 (dd, 3H), 4.9 (m, 1H), 64 (m, 1H), 7.0 (d,
2H), 7.2-7.4 (m, 3H), 7.5 (m, 4H); 13C NMR, ꢂ 9.4, 107.7,
116.4, 126.8, 126.9, 128.2, 128.7, 135.4, 140.6, 140.8,
157.0; LRMS, m/z 211 (M H) (base), 171; HRMS, m/z
calculated for C15H15O 211.1123; found 211.1118.
3-Chlorophenyl propenyl ether. Found to be 98% pure
by GC: b.p. 50–51°C at 1 Torr; 1H NMR, ꢂ 1.6 (dd, 3H),
4.8 (m, 1H), 6.2 (m, 1H), 68 (m, 1H), 6.9 (m, 1H), 7.1 (m,
2H); 13C NMR, ꢂ 9.4, 108.7, 114.4, 116.6, 122.5, 130.3,
135.0, 140.2, 158.2; LRMS, m/z 169 (M H) (base),
155, 149, 145, 141, 129, 125; HRMS, m/z calculated for
C9H11OCl 169.0420; found 169.0426.
3,4-Dimethylphenyl propenyl ether. Found to be 96%
pure by GC: b.p. 49–50°C at 2 Torr; 1H NMR, ꢂ 1.7 (dd,
3H), 2.1 (d, 6H), 4.7 (m, 1H), 6.28 (m, 1H), 6.7 (m, 2H),
6.9 (d, 1H); 13C NMR, ꢂ 9.4, 18.8, 19.8, 106.3, 113.4,
117.7, 140.3, 130.5, 137.8, 141.6, 155.9; LRMS, m/z 163
Acknowledgments
The authors express thanks to the National Science
Foundation (CHE-9610227) and the Robert A. Welch
Foundation (F-149) for support of this research.
1998 John Wiley & Sons, Ltd.
JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, VOL. 11, 15–24 (1998)