Page 7 of 14
The Journal of Organic Chemistry
MHz, CDCl3, 298 K) δH 7.42–7.38 (m, 2H), 7.35–7.30 (m, 2H),
0.1 equiv), trimethylacetyl chloride (3.2 mL, 26 mmol, 1.3
1
2
3
4
5
6
7
8
equiv), and dichloromethane (50 mL, 0.4 M). The crude ester
was purified by column chromatography on silica gel (slow
gradient of 0–10 % EtOAc in hexanes) to afford 2.9 g (63%
yield) of the desired product as a clear oil which solidifies over
7.27 (d, J = 6.7 Hz, 1H), 6.70–6.60 (m, 1H), 6.29 (dt, J = 16.0,
6.3 Hz, 1H), 4.73 (dd, J = 6.3, 1.4 Hz, 2H), 1.24 (s, 9H); C
NMR (101 MHz, CDCl3, 298 K) δC 178.5, 136.5, 133.7, 128.7,
128.1, 126.7, 123.8, 65.1, 39.0, 27.4. The spectral data for this
13
1
34
time to a white solid. H NMR (400 MHz, CDCl3, 298 K) δH
compound matches that reported in the literature
7.45–7.36 (m, 2H), 7.35–7.29 (m, 2H), 7.28–7.22 (m, 1H), 6.59
(dd, J = 16.0, 1.1 Hz, 1H), 6.19 (dd, J = 16.0, 6.4 Hz, 1H), 5.51
(qdd, J = 6.5, 6.5, 1.3 Hz, 1H), 1.39 (d, J = 6.5 Hz, 3H), 1.22 (s,
1-Phenylallyl pivalate (7c’) was prepared according to General
Procedure C, using benzaldehyde (1.0 mL, 10 mmol, 1.0 equiv),
vinylmagnesium bromide (1.0 M solution in THF, 12 mL, 12
mmol, 1.2 equiv), and THF (10 mL, 1.0 M). The crude alcohol
(S14) was used directly in the next step according to General
Procedure B, using S14 (1.2 g, 8.6 mmol, 1.0 equiv), triethyla-
mine (1.7 mL, 12 mmol, 1.4 equiv), DMAP (0.11 g, 0.86 mmol,
0.1 equiv), trimethylacetyl chloride (1.4 mL, 11 mmol, 1.3
equiv), and dichloromethane (15 mL, 0.57M). The crude ester
was purified by column chromatography on silica gel (slow
gradient of 0-10% EtOAc in hexanes) to afford 0.83 g (38 %
13
9H); C NMR (101 MHz, CDCl3, 298 K) δC 177.7, 136.5, 131.0,
129.1, 128.5, 127.8, 126.5, 70.5, 38.8, 27.1, 20.3; IR (neat)
9
-1
2975, 2936, 2911, 2873, 1709, 1479, 1162, 1148, 753 cm . The
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
spectral data for this compound matches that reported in the
28a
literature.
(E)-1-Phenylbut-2-en-1-yl pivalate (7a’) was prepared accord-
ing to General Procedure C, using crotonaldehyde (predomi-
nantly trans, 0.83 mL, 10 mmol, 1.0 equiv), PhMgBr (1.0 M
solution in THF, 12 mL, 12 mmol, 1.2 equiv), and THF (12 mL,
0.83 M). The crude alcohol (S12) was purified via column
chromatography (slow gradient of 5–15% EtOAc in Hexanes) to
afford 1.2 g (82% yield) of the desired product as a clear oil,
which was used directly in the next step according to General
Procedure B, using S12 (1.22 g, 8.2 mmol, 1.0 equiv) ), triethyl-
amine (1.6 mL, 12 mmol, 1.4 equiv), DMAP (0.10 g, 0.82
mmol, 0.1 equiv), trimethylacetyl chloride (1.3 mL, 11 mmol,
1.3 equiv), and dichloromethane (12 mL, 0.68 M). The crude
ester was purified by column chromatography (slow gradient of
0-10% EtOAc in Hexanes) to afford 1.6 g (82% yield) of the
1
yield over 2 steps) of the desired product as a clear oil. H NMR
(400 MHz, CDCl3, 298 K) δH 7.40–7.27 (m, 5H), 6.23 (ddd, J =
5.8, 1.4, 1.4 Hz, 1H), 5.99 (ddd, J = 17.1, 10.4, 5.8 Hz, 1H),
5.30 (ddd, J = 17.1, 1.4, 1.4 Hz, 1H), 5.23 (ddd, J = 10.4, 1.3,
13
1.3 Hz, 1H), 1.24 (s, 9H); C NMR (101 MHz, CDCl3, 298 K) δC
177.4, 139.4, 136.7, 128.6, 128.1, 127.0, 116.6, 75.9, 39.0, 27.3.
The spectral data for this compound matches that reported in the
35
literature.
1-(4-(tert-Butyl)phenyl)allyl pivalate (7d’) was prepared ac-
cording to General Procedure C, using 4-(tert-
butyl)benzaldehyde (1.5 mL, 9.0 mmol, 1.0 equiv), vinylmagne-
sium bromide (1.0 M solution in THF, 10 mL, 10 mmol, 1.1
equiv), and THF (10 mL, 0.9 M). The crude alcohol (S15) was
of sufficient purity for use directly in the next step according to
General Procedure B, using S15 (0.86 g, 4.5 mmol, 1.0 equiv),
triethylamine (0.88 mL, 6.3 mmol, 1.4 equiv), DMAP (0.06 g,
0.45 mmol, 0.10 equiv), trimethylacetyl chloride (0.75 mL, 5.9
mmol, 1.3 equiv), and dichloromethane (8.0 mL, 0.56 M). The
crude ester was purified by column chromatography on silica
gel (slow gradient of 0-10% EtOAc in hexanes) to afford 0.86 g
1
desired product as a as a clear oil (95:5 E/Z). H NMR (400
MHz, CDCl3, 298 K) δH 7.44–7.30 (m, 5H), 6.27–6.19 (m, 1H),
5.85–5.72 (m, 1H), 5.66 (ddq, J = 15.3, 6.7, 1.3 Hz, 1H), 1.78–
13
1.71 (m, 3H), 1.26 (s, 9H); C NMR (101 MHz, CDCl3, 298 K)
δC 177.4, 140.2, 129.9, 129.0, 128.4, 127.7, 126.6, 75.9, 38.9,
27.2, 17.8; IR (neat) 2973, 2936, 2873, 1727, 1479, 1277, 1144,
-1
962, 696 cm . The spectral data for this compound matches that
28a
reported in the literature.
(E)-1-Phenylpent-1-en-3-yl pivalate (7b) was prepared accord-
ing to General Procedure A, using cinnamaldehyde (1.3 mL, 10
mmol, 1.0 equiv), EtMgBr (1.7 M solution in diethyl ether, 8.8
mL, 15 mmol, 1.5 equiv), and THF (20 mL, 0.50 M). The crude
alcohol (S13) was of sufficient purity for use directly in the next
step according to General Procedure B using S13 (1.1 g, 6.7
mmol, 1.0 equiv), triethylamine (1.3 mL, 9.4 mmol, 1.4 equiv),
DMAP (0.08g, 0.67 mmol, 0.10 equiv), trimethylacetyl chloride
(1.1 mL, 8.7 mmol, 1.3 equiv), and dichloromethane (12 mL,
0.56 M). The crude ester was purified by column chromatog-
raphy on silica gel (slow gradient of 0-10% EtOAc in hexanes)
to afford 0.98 g (59 % yield over 2 steps) of the desired product
1
(35 % yield over 2 steps) of the desired product as a clear oil. H
NMR (400 MHz, CDCl3, 298 K) δH 7.39–7.34 (m, 2H), 7.29–
7.25 (m, 2H), 6.21 (dd, J = 5.9, 1.4 Hz, 1H), 5.98 (ddd, J = 17.2,
10.5, 5.9 Hz, 1H), 5.30 (ddd, J = 17.1, 1.4, 1.4 Hz, 1H), 5.21
13
(ddd, J = 10.4, 1.4, 1.4 Hz, 1H), 1.31 (s, 9H), 1.24 (s, 9H); C
NMR (101 MHz, CDCl3, 298 K) δC 177.3, 150.8, 136.7, 136.2,
126.4, 125.4, 116.2, 75.6, 38.9, 34.5, 31.3, 27.1; IR (neat) 2964,
-1
2906, 2871, 1729, 1479, 1276, 1146, 931 cm ; HRMS (DART-
+
TOF+) m/z: [M+NH4] calcd for C18H30NO2 292.2277; found
292.2279.
1
1-(4-Isopropylphenyl)allyl pivalate (7e’) was prepared accord-
ing to General Procedure D, using cuminaldehyde (0.76 mL, 5.0
mmol, 1.0 equiv), vinylmagnesium bromide (1.0 M solution in
THF, 5.5 mL, 5.5 mmol, 1.1 equiv), THF (8.0 mL, 0.63 M), and
trimethylacetyl chloride (0.92 mL, 7.5 mmol, 1.5 equiv). The
crude ester was purified by column chromatography on silica
gel (slow gradient of 0–10% EtOAc in hexanes) to afford 0.45 g
as a clear oil. H NMR (400 MHz, CDCl3, 298 K) δH 7.45–7.40
(m, 2H), 7.39–7.31 (m, 2H), 7.31–7.24 (m, 1H), 6.68–6.57 (m,
1H), 6.16 (dd, J = 16.0, 6.9 Hz, 1H), 5.37 (dt, J = 8.0, 6.3 Hz,
1H), 1.87–1.67 (m, 2H), 1.26 (s, 9H), 0.98 (t, J = 7.4 Hz, 3H);
13
C NMR (101 MHz, CDCl3, 298 K) δC 177.8, 136.6, 131.9,
128.5, 127.9, 127.8, 126.5, 75.4, 38.9, 27.7, 27.2, 9.5; IR (neat)
-1
2971, 2936, 2876, 1724, 1495, 1279, 1153, 936, 745, 691 cm ;
HRMS (DART-TOF+) m/z: [M] calcd for C16H22O2 246.1620;
found 246.1630.
1
+
(35% yield) of the desired product as a slightly yellow oil. H
NMR (400 MHz, CDCl3, 298 K) δH 7.29–7.24 (m, 2H), 7.24–
7.17 (m, 2H), 6.21 (ddd, J = 5.9, 1.4, 1.4 Hz, 1H), 5.98 (ddd, J =
17.2, 10.4, 5.8 Hz, 1H), 5.29 (ddd, J = 17.1, 1.4, 1.4 Hz, 1H),
5.21 (ddd, J = 10.4, 1.4, 1.4 Hz, 1H), 2.90 (hept, J = 6.9 Hz,
Cinnamyl pivalate (7c) was prepared according to General
Procedure B, using cinnamyl alcohol (2.0 g, 15 mmol, 1.0
equiv), triethylamine (2.9 mL, 21 mmol, 1.4 equiv), DMAP
(0.18 g, 1.5 mmol, 0.1 equiv), trimethylacetyl chloride (2.4 mL,
20 mmol, 1.3 equiv), and dichloromethane (30 mL, 0.5 M). The
crude ester was purified by column chromatography on silica
gel (slow gradient of 0-5% EtOAc in hexanes) to afford 1.8 g
13
1H), 1.26 – 1.22 (m, 15H); C NMR (101 MHz, CDCl3, 298 K)
δC 177.5, 148.7, 136.9, 136.8, 126.9, 126.7, 116.4, 75.8, 39.03,
34.0, 27.3, 24.1, 24.1; IR (neat) 2961, 2932, 2872, 1729, 1277,
-1
1144, 825 cm ; HRMS (DART-TOF+) m/z: [M+NH4] calcd for
+
C17H28NO2 278.2120; found 278.2118.
1
(54 % yield) of the desired product as a clear oil. H NMR (400
7
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