9
40
R. Csuk – A. Niesen · Synthesis and Biological Evaluation of a “Natural” Insect Repellent
etate 10:1) to afford 15 (4.2 g, 96%) as a colourless liquid. by chromatography (silica gel, hexane/ethyl acetate 9:1)
IR (film): ν = 3077m, 2926s, 2855s, 1712s, 1641m, 1548w, to afford 18 (2.92 g, 80%) as a colourless liquid. RF
−1
1
1
464m, 1413m, 1286m, 1118w cm . – H NMR (400 MHz, (hexane/ethyl acetate 9:1) = 0.5. – IR (film): ν = 2927s,
CDCl ): δ = 1.20 − 1.40 (m, 12 H, CH ), 1.60 (m, 2 H, 2854s, 1465m, 1455m, 1440m, 1383m, 1365m, 1352m,
3
2
3
3
CH ), 2.0 (dd, J
= 6.87 Hz, J
= 6.87 Hz, 2 H, CH - 1322m, 1260m, 1200s, 1184m, 1163m, 1136s, 1120s,
2
H,H
H,H
2
3
C = C), 2.30 (t, JH,H = 7.4 Hz, 2 H, 2 H, CH -COOH), 1078s, 1034s, 988m, 905m, 869m, 815m, 722m, 646m,
2
−1
1
4
1
(
.90 (m, 1 H, CH = C), 4.95 (m, 1 H, CH = C), 5.80 (m, 564w cm . – H NMR (400 MHz, CDCl ): δ = 1.25−1.35
2
13
2
3
H, CH = C). – C NMR (125 MHz, CDCl ): δ = 24.7 (m, 10 H, CH ), 1.40 (m, 2 H, CH ), 1.45 – 1.60 (m, 6 H,
3
2
2
CH ), 28.9 (CH ), 29.1 (CH ), 29.1 (CH ), 29.2 (CH ), CH ), 1.70 (m, 1 H, CH ), 1.80 (m, 3 H, CH -CH Br,
2 2 2 2 2 2 2 2 2
2
1
7
8
9.4 (CH2), 29.4 (CH2), 33.8 (CH2), 34.1 (CH2), CH , THP), 3.35 (m, 3 H, CH Br, CH -O), 3.45 (m, 1 H,
2 2 2
2
3
14.1 (CH = C), 139.2 (CH = C), 180.1 (C = O). – MS (EI, CH , THP), 3.70 (ddd, JH,H = 9.5 Hz, J
= 6.84 Hz,
2
2
2
H,H
2
0 eV): m/z(%) = 55 (100), 60 (21), 69 (70), 73 (30),
3 (39), 96 (39), 110 (21), 114 (13), 123 (12), 138 (17), 4.55 (dd, J
JH,H = 6.84 Hz, 1 H, CH ), 3.85 (m, 1 H, CH , THP),
2
3
3
= 4.35 Hz, J
= 2.48 Hz, 1 H, CH). –
H,H
H,H
1
3
1
51 (4), 162 (4), 180 (10), 198 (1). – HRMS for C H O :
C NMR (100 MHz, CDCl ): δ = 19.8 (CH , THP),
12
22
2
3 2
calcd. 298.16198; found 198.16200.
25.6 (CH , THP), 26.2 (CH ), 28.2 (CH ), 28.8 (CH ),
2 2 2 2
2
9.4 (CH ), 29.5 (CH ), 29.5 (CH ), 29.8 (CH ), 30.9 (CH ,
2 2 2 2 2
1
1, 12-Dibromododecyl-tetrahydro-2H-2-pyranyl ether (16)
THP), 32.9 (CH2-CH2Br), 34.0 (CH2-Br), 62.3 (CH2-O,
THP), 67.7 (CH -O), 98.8 (CH). – MS (GC-MS, EI, 70 eV):
m/z(%) = 85 (100), 101 (8), 115 (2), 137 (2), 163 (1),
2
◦
To a −15 C cold solution of 7 (0.2 g, 0.75 mmol) in
abs. dichloromethane (10 ml) a solution of bromine (0.1 g,
.63 mmol) in abs. dichloromethane (3 ml) was slowly
1
90 (1), 219 (1), 241 (1), 247 (2), 267 (1), 292 (1), 319 (3). –
0
Analysis for C H BrO (349.35): calcd. C 58.45, H 9.52;
1
7
33
2
added, then the volatiles were removed in vacuo and the
residue was subjected to chromatography (silica gel, hex-
ane/ethyl acetate 9:1) to yield 16 (0.14 g, 54%) as a colour-
less liquid. RF (hexane/ethyl acetate 9:1) = 0.54. – IR (film):
ν = 2927s, 2854s, 1742w, 1465m, 1440w, 1352w, 1322w,
found C 58.31, H 9.67.
1
9-Icosen-11-ynyltetrahydro-2H-2-pyranyl ether (20)
◦
To a −10 C cold solution of 3 (0.8 g, 3.0 mmol) in abs.
1
9
260w, 1200m, 1184w, 1136m, 1120m, 1078m, 1033s,
−
1
1
THF (15 ml) a solution of n-BuLi (3.15 mmol, 1.6 M in hex-
ane) was slowly added, stirring at that temperature was con-
tinued for 1 h and a solution of 19 (3.5 g, 3.15 mmol) in
89w cm . – H NMR (400 MHz, CDCl ): δ = 1.20−1.40
3
(m, 13 H, CH ), 1.60 (m, 7 H, CH ), 1.65 – 1.85 (m, 3 H,
2 2
2
CH ), 2.10 (m, 1 H, CH ), 3.35 (ddd, JH,H = 9.55 Hz,
2
2
◦
3
3
HMPT (8 ml) was slowly added at −18 C. The mixture was
JH,H = 6.64 Hz, J
= 6.64 Hz, 1 H, CH -O), 3.45 (m,
H,H
2
3
allowed to warm to room temperature and stirring was con-
tinued for another 12 h, then the reaction was stopped by the
addition of water (11 ml). The phases were separated, the
aq. phase was extracted with hexane (3×100 ml), the com-
bined organic layers were washed with water (2×20 ml) and
1
H, CH , THP), 3.60 (t, JH,H = 10.17 Hz, 1 H, CH -
2
2
2
3
3
Br), 3.70 (ddd, J
= 9.55 Hz, J
= 6.85 Hz, J
=
H,H
H,H
H,H
6
4
2
.85 Hz, 1 H, CH -O), 3.85 (m, 2 H, CH , THP, CH -Br),
2
2
2
3
3
.15 (m, 1 H, CH-Br), 4.55 (dd, J
= 4.56 Hz, J
=
H,H
H,H
.49 Hz, 1 H, O-CH-O). – 1 C NMR (100 MHz, CDCl3):
3
brine (15 ml) and dried (Na SO ). After evaporation of the
2
4
δ = 19.7 (CH ), 25.6 (CH ), 26.3 (CH ), 26.8 (CH ),
2
2
2
2
solvents the residue was purified by chromatography (silica
gel, hexane/ethyl acetate 98:2) to yield 20 (0.64 g, 57%) as
a colourless liquid. RF (hexane/ethyl acetate 9:1) = 0.6. –
IR (film): ν = 3333w, 3076w, 2926s, 2855s, 2360w, 1737w,
2
2
8.8 (CH2), 29.4 (CH2), 29.5 (CH2), 29.5 (CH2),
9.8 (CH ), 30.8 (CH ), 36.1 (CH -CHBr), 36.4 (CH -
2
2
2
2
Br), 53.1 (CH-Br), 62.3 (CH -O, THP), 67.7 (CH -O), 98.8
2
2
(O-CH-O, THP). – MS (GC-MS, EI, 70 eV): m/z(%) =
1
1
8
1
1
676w, 1640m, 1465m, 1440m, 1352m, 1323m, 1284w,
260m, 1200s, 1184m, 1137s, 1079s, 1034s, 992m, 908s,
69m, 815m cm . – H NMR (400 MHz, CDCl ): δ =
8
5 (100), 101 (8), 123 (2), 163 (1), 189 (1), 211 (1), 245 (1),
2
67 (1), 324 (1), 353 (1), 355 (1), 427 (3). – HRMS for
−1
1
3
C H Br O : calcd. 426.0769; found 426.0770.
1
7
32
2 2
.20 − 1.60 (m, 28 H, CH ), 1.70 (m, 1 H, CH ), 1.80 (m,
2
2
3
3
H, CH ), 2.00 (dd,
J
= 6.84 Hz, J
= 6.84 Hz,
2
H,H
H,H
1
0-Bromodecyl tetrahydro-2H-2-pyranyl ether (18)
solution of 10-bromo-1-decanol (17) (3.0 g,
2
J
H, CH -C = C), 2.15 (m, 4 H, CH -C ≡ C), 3.35 (ddd,
2
2
2
3 3
A
= 9.53 Hz, J
= 6.63 Hz, J
= 6.63 Hz, 1 H,
H,H
H,H
H,H
2
1
1.39 mmol) containing DHP (1.43 g, 17,0 mmol) and CH -O), 3.45 (m, 1 H, CH -O, THP), 3.70 (ddd, JH,H =
2 2
3
3
PPTA (28 mg, 0.11 mmol) in dry dichloromethane (50 ml) 9.51 Hz, JH,H = 6.83 Hz, JH,H = 6.84 Hz, 1 H, CH -
was stirred for 2 days at room temperature, then an aq. O), 3.85 (m, 1 H, CH -O, THP), 4.55 (dd, THP, JH,H
2
=
3
2
3
solution of Na CO3 (2 M, 11 ml) was added, the layers 4.35 Hz, J
= 2.69 Hz, 1 H, O-CH-O), 4.90 (m, 1 H,
2
H,H
were separated and the organic phase was dried (K CO ). CH = C), 4.95 (m, 1 H, CH = C) 5.80 (m, 1 H, CH = C). –
2
3
2
2
1
3
The solvents were removed and the residue was purified
C NMR (100 MHz, CDCl ): δ = 18.8 (CH ), 18.9 (CH ),
3 2 2
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