232 JOURNAL OF CHEMICAL RESEARCH 2015
reaction mixture was stirred at room temperature for 10 min followed
by cooling to 0 C and subsequent addition of triphenylphosphine (2.0
thoroughly mixing NaBH (1.0 g) with neutral alumina (9.0 g) in solid
4
o
state by grinding in a mortar) (0.02 g, 0.48 mmol) was thoroughly
mixed with neat compound 9 (0.21 g, 0.48 mmol) in a test tube and
placed in an alumina bath inside the microwave oven and irradiated
at 640 W for 1 min. Upon cooling, the reaction mixture was extracted
with diethyl ether (2 x 15 mL) and brine and then dried. Evaporation of
the solvent under reduced pressure provided 12-hydroxyhentriacontane
g, 7.64 mmol). Stirring was continued overnight at room temperature.
The mixture was then passed through a short silica gel column and
eluted with dichloromethane (20 mL). The solvent was evaporated
under reduced pressure to furnish pure 1-bromononadecane (6, 0.73
o
o
-
g, 77%) as a white solid, m.p. 35–36 C (lit. 37 C). IR (neat)/ν cm
max
1
1
o
o
:
2960, 1420, 580. H NMR(CDCl , 300 MHz) δ 0.91 (t, J=6Hz,
(1, 0.19 g, 92%) as a white solid, m.p. 75 C(lit. 77 C). IR (CHCl )/ν
3
3
max
3
H, -CH CH ), 1.22–1.64 (bs, 32H, saturated methylene protons),
cm-1: 3430, 2920, 2852, 1465, 1070, 720.
1
H NMR (CDCl , 300 MHz)
2
3
3
1
.85–2.17 (m, 2H, –CH CH Br), 3.34 (t, J=6Hz, 2H, –CH CH Br).
2
2
2
2
δ 0.94 (t, J=6Hz, 6H, 2 x -CH CH ), 1.13–1.66 (bs, 52H, saturated
methylene protons), 1.84–2.00 (m, 4H, –CH CH(OH)CH –), 3.71
2 2
2 3
1
3
C NMR (CDCl , 300 MHz) δ 33.8, 32.9, 32.0, 29.7, 29.5, 29.4, 28.8,
3
2
8.3, 22.7, 14.1.
(
t, J=8Hz, 1H, –CH(OH)–), 4.25 (bs, 1H, –OH, D O exchangeable).
2
2
3
Docos-1-en-3-ol (7): A flame-dried nitrogen-flushed 250 mL
13
C NMR (CDCl 300 MHz) δ 71.7, 37.9, 37.7, 32.0, 29.7, 29.6, 29.5,
3,
three-necked round-bottomed flask, fitted with a condensor and an
additional funnel was charged with magnesium turnings (0.14 g, 5.76
mmol) and anhyd. diethyl ether (10 mL). To this stirred mixture was
added a few drops of 1-bromononadecane (6, 2.0 g, 5.76 mmol) in dry
diethyl ether (50 mL). Upon warming the flask on hot water bath, the
remaining 1-bromononadecane (6) was added dropwise over a period
of 0.5 h. On complete consumption of magnesium metal, the reaction
2
9.2, 28.0, 25.8, 23.5, 23.0, 22.8, 14.1, 13.9.
Conclusions
A highly efficient methodology for the synthesis of compound 1
accelerated by microwave irradiation and ultrasonic conditions
has been developed. The rate of formation of the Zn–Cu couple,
use of solid state medium and chemoselective formation of
bromo alkanols under microwave irradiation are important
favourable conditions. Furthermore, all heterogeneous reactions
using metals have shown remarkable improvements in terms of
yield and selectivity under sonochemical conditions. Continuous
efforts to develop novel strategies for useful natural products
are underway and will be reported in due course.
o
mixture was cooled to 0 C and acrolein (0.3 g, 5.35 mmol) in dry
diethyl ether (25 mL) was added dropwise over a period of 1 h. Stirring
was continued overnight and then the reaction mixture was quenched
with saturated aq. ammonium chloride solution. The organic layer
was separated and washed with water (2 x 10 mL), brine and dried.
Removal of solvent under reduced pressure followed by purification
using a silica gel column chromatography eluting with 10% ethyl
acetate in n-hexane furnished pure docos-1-en-3-ol (7, 1.4 g, 75%) as a
-
1
colourless oil. IR (neat)/ν cm : 3350, 3010, 2920, 1640, 1280, 1160,
The authors are grateful to Council of Scientific and Industrial
Research (CSIR) and University Grant Commission (UGC) for
providing financial support for this work.
max
1
7
25. H NMR(CDCl , 300 MHz) δ 0.91 (t, J=6Hz, 3H, –CH CH ),
3
2
3
1.14–1.63 (m, 34H, saturated methylene protons), 1.82–2.00 (m, 2H, –
CH CH(OH)–), 3.22 (bs, 1H, –OH, D O exchangeable), 3.90–4.38 (m,
2
2
1
1
3
H, –CH CH(OH)–), 5.00–5.45 (m, 2H, –CH=CH ), 5.72–6.31 (m,
Received 28 January 2015; accepted 26 March 2015
Paper 1503171 doi: 10.3184/174751915X14280537678829
Published online: 13 April 2015
2
2
13
H, –CHCH=CH ). C NMR (CDCl , 300 MHz) δ 141.5, 114.3, 72.9,
2
3
9.3, 29.3, 25.1, 22.7, 21.0, 18. 7, 18.5, 14.0.
Docos-1-en-3-one (8): To a stirred suspension of pyridinium
dichromate (2.32 g, 6.17 mmol) in dry dichloromethane (50 mL)
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1
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o
3
.09 mmol) in dry dichloromethane (50 mL) at 0–10 C. Stirring was
continued for 9 h and then the reaction mixture was passed through
a short alumina (active, 30 g) column. Evaporation of solvent under
reduced pressure provided pure docos-1-en-3-one (8, 0.69 g, 70%)
2
H.L. Meiselman, B.P. Halpern and G.P. Dateo, Physiol. Behav., 1976, 17,
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3
4
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-1
as a colourless oil. IR (neat)/ν cm : 3020, 2960, 1700, 1660, 1420,
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1
1
210, 720. H NMR (CCl , 60 MHz) δ 0.93 (t, J=6Hz, 3H, –CH CH ),
4
2
3
1.14–1.60 (bs, 34H, saturated methylene protons), 2.53 (t, J=6Hz, 2H,
–
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7
8
9
2
2
13
CH=CHH), 6.52 (m, 1H, –CH=CH ). C NMR (CDCl , 300 MHz)
2
3
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o
mL of aq. ethanol (9:1) at 0 C ,was added zinc dust (0.22 g, 3.46 mmol),
1
0
copper (I) iodide (0.2 g, 1.07 mmol) and the mixture was sonicated
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mL) over a period of 5 min. followed by addition of compound (8, 0.5 g,
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1
4
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1.55 mmol) in ethanol (2 mL) dropwise. After sonication for 30 min. the
3
reaction was quenched with brine and the solvent was evaporated under
reduced pressure. Diethyl ether (30 mL) was added and the solution
washed with water (2 x 5 mL) and brine and then dried. Evaporation
of the solvent under reduced pressure followed by silica gel column
purificaton using n-hexane:ethyl acetate (9:1) gave pure 9 (0.43 g, 62%)
15
5
1
17 E.J. Corey and G. Schmidt, Tetrahedron Lett., 1979, 399.
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o
-1
as a white solid, m.p. 79–81 C. IR (CHCl )/ν cm : 2860, 1710, 1440,
7
3
max
1
20. H NMR(CDCl , 300 MHz) δ 0.92 (t, J=6Hz, 6H, 2 x –CH CH ),
3
2
3
1
.23–1.77 (bs, 52H, saturated methylene protons), 2.11–2.56 (m, 4H, –
21
E. Banaszak, L.W. Xu, J.F. Bardeau, A.S. Castanet and J. Mortier,
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13
CH COCH –). C NMR (CDCl , 300 MHz) δ 211.7, 42.6, 42.5, 31.9,
2
2
3
2
9.5, 29.4, 29.3, 26.1, 24.1, 24.0, 22.7, 14.1, 13.9.
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2
2
J.R.A. Dulayymi, M.S. Baird and E. Roberts, Tetrahedron, 2005, 61, 11939.
1
23 A.A. Khan, S.H. Chee, B.L. Stocker and M.S.M. Timmer, Eur. J. Org.
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