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F.-P. Liu et al. / Tetrahedron: Asymmetry 26 (2015) 961–965
by silica gel chromatography (n-hexane/ethyl acetate 2:1) to give 6
(1.16 g, 87% yield) as a white solid. Mp 28–29 °C. 1H NMR
(300 MHz, CDCl3): d 3.64 (q, J = 6.5 Hz, 2H), 2.16–2.11 (m, 4H),
1.59–1.28 (m, 25H), 0.89 (t, J = 6.8 Hz, 3H). 13C NMR (75 MHz,
CDCl3): d 80.23, 80.19, 63.0, 32.8, 31.4, 29.53, 29.45, 29.4, 29.15,
29.13, 28.8, 28.5, 25.7, 22.6, 18.8, 18.7, 14.0. (One resonance was
not observed due to overlapping.) HRMS (APCI-TOF) calcd for
[M+H]+ C18H35O 267.2688, found: 267.2700.
monitored by TLC at the same temperature, and filtered through
a Celite pad. The filtrate was concentrated under reduced pressure
and purified by silica gel chromatography (n-hexane/ethyl acetate
2:1) to afford 9 (1.05 g, 89% yield) as a colorless oil. 1H NMR
(300 MHz, CDCl3): d 5.72–5.58 (m, 2H), 5.36 (t, J = 4.5 Hz, 2H),
4.07 (d, J = 4.1 Hz, 2H), 2.07–1.98 (m, 6H), 1.51–1.27 (m, 23H),
0.88 (t, J = 6.8 Hz, 3H). 13C NMR (75 MHz, CDCl3): d 133.5, 129.9,
129.8, 128.8, 63.8, 32.2, 31.8, 29.73, 29.71, 29.55, 29.51, 29.46,
29.3, 29.2, 29.1, 29.0, 27.18, 27.17, 22.6, 14.1. HRMS (ESI-TOF) calcd
for C20H39O [M+H]+: 295.3001, found: 295.2995.
4.2.5. Octadec-11-ynal 7
To a stirred solution of alkynol 6 (4.3 g, 16 mmol) in CH2Cl2
(50 mL) was added iodobenzene diacetate (5.7 g, 17.6 mmol) at
25 °C. The resulting mixture was cooled to 0 °C, and the solution
of 2,2,6,6-tetramethyl-1-piperidinyloxy (276 mg, 1.76 mmol) in
CH2Cl2 (2 mL) was added slowly. The reaction mixture was stirred
at 25 °C until the complete consumption of 6 was observed by TLC.
The reaction solution was quenched with saturated aqueous
Na2S2O3 solution (20 mL), and the aqueous phase was extracted
with CH2Cl2 (3 Â 50 mL). The combined organic phases were
washed with water (30 mL) and brine (30 mL) successively, dried
over anhydrous MgSO4 and concentrated under reduced pressure.
The residue was purified by silica gel chromatography (n-hex-
ane/ethyl acetate 20:1) to afford 7 (3.84 g, 91% yield) as a colorless
oil. 1H NMR (300 MHz, CDCl3): d 9.76 (t, J = 1.7 Hz, 1H), 2.45–2.39
(m, 2H), 2.16–2.11 (m, 4H), 1.65–1.58 (m, 2H), 1.47–1.30 (m,
20H), 0.89 (t, J = 6.7 Hz, 3H). 13C NMR (75 MHz, CDCl3): d 202.7,
80.2, 80.1, 43.8, 31.3, 29.3, 29.1, 29.0, 28.7, 28.5, 22.5, 22.0, 18.7,
18.6, 14.0. (Three resonances were not observed due to overlap-
ping.) HRMS (APCI-TOF) calcd for [M+H]+ C18H33O 265.2531,
found: 265.2501.
4.2.8. (2E,13Z)-Icosa-2,13-dienal 10
According to the similar procedure described above for acetyle-
nic aldehyde 7, diolefinc alcohol 9 (4.70 g, 16 mmol) was converted
into 10 (4.25 g, 91% yield) as a colorless oil. 1H NMR (300 MHz,
CDCl3): d 9.51 (d, J = 7.9 Hz, 1H), 6.85 (dt, J = 15.6, 6.8 Hz, 1H),
6.16–6.07 (m, 1H), 5.35 (t, J = 5.4 Hz, 2H), 2.37–2.30 (m, 2H),
2.09–1.98 (m, 4H), 1.53–1.25 (m, 22H), 0.88 (t, J = 6.8 Hz, 3H). 13C
NMR (75 MHz, CDCl3): d 194.0, 158.9, 132.9, 129.9, 129.7, 32.7,
31.7, 29.7, 29.43, 29.42, 29.3, 29.2, 29.1, 28.9, 27.9, 27.2, 27.1,
22.6, 14.0. (One resonance was not observed due to overlapping.)
HRMS (APCI-TOF) calcd for [M+H]+ C20H37O: 293.2844, found:
293.2857.
4.2.9. (S,4E,15Z)-1-(Trimethylsilyl)docosa-4,15-dien-1-yn-3-ol 11
To a solution of the (R,R)-ProPhenol ligand (25.6 mg, 0.04 mmol,
0.20 equiv) and P(O)Ph3 (22.3 mg, 0.08 mmol, 0.40 equiv) in
toluene (2 mL) was added trimethylsilylacetylene (59.0 mg,
0.60 mmol, 3 equiv) at 0 °C under argon. A solution of Me2Zn
(0.5 mL, 1.2 M in toluene, 0.60 mmol, 3 equiv) was then added
slowly at the same temperature. The resulting mixture was
warmed to 25 °C and stirred for 90 min, then cooled to 0 °C. After
diolefinc aldehyde 10 (58.5 mg, 0.20 mmol, 1 equiv) was added,
the reaction was maintained for 48 h at 0 °C. The reaction solution
was quenched with a saturated aqueous NH4Cl solution (5 mL),
and the aqueous phase was extracted with Et2O (3 Â 10 mL). The
organic layers were dried over anhydrous Na2SO4, and concen-
trated under reduced pressure. The residue was purified by silica
gel chromatography (n-hexane/ethyl acetate 10:1) to give 11
(62.4 mg, 80% yield, 81% ee) as a colorless oil. Enantiomeric excess
was determined by HPLC with a Daicel Chiralcel OD-H column (2%
2-propanol in n-hexane, 0.8 mL/min, 254 nm); minor (R)-enan-
tiomer tr = 5.52 min, major (S)-enantiomer tr = 6.38 min.
4.2.6. (E)-Icos-2-en-13-yn-1-ol 8
To a stirred mixture of NaH (0.240 g, 60% in mineral oil,
6 mmol) in THF (5 mL) was slowly added triethylphosphonoac-
etate (1.2 mL, 6 mmol) at 0 °C. After stirring for 30 min, acetylenic
aldehyde 7 (1.58 g, 6 mmol) was added. The reaction was main-
tained for 30 min at the same temperature, warmed to room tem-
perature slowly and stirred for 16 h. The reaction solution was
diluted with Et2O (10 mL) and washed with saturated aqueous
Na2CO3 solution (10 mL). The combined organic phases were dried
over anhydrous MgSO4, and concentrated under reduced pressure
to obtain the crude (E)-ethyl icos-2-en-13-ynoate as a colorless oil.
To a stirred solution of the crude (E)-ethyl icos-2-en-13-ynoate
in THF (10 mL) was added dropwise DIBAL-H (12.0 mL, 1.0 M in n-
hexane, 12.0 mmol) at À78 °C. The reaction mixture was stirred for
2 h at the same temperature and then warmed to room tempera-
ture slowly. The reaction solution was quenched with saturated
aqueous NH4Cl solution (3 mL). The aqueous phase was extracted
with CH2Cl2 (15 mL) dried over anhydrous Na2SO4, and concen-
trated under reduced pressure. The residue was purified by silica
gel chromatography (n-hexane/ethyl acetate 2:1) to furnish 8
[a]
20 = +11.0 (c 0.5, MeOH). 1H NMR (300 MHz, CDCl3): d 5.87 (dt,
D
J = 15.2, 6.8 Hz, 1H), 5.58 (dd, J = 15.2, 6.1 Hz, 1H), 5.35 (t,
J = 4.7 Hz, 2H), 4.82 (t, J = 5.8 Hz, 1H), 2.09–1.98 (m, 6H), 1.86 (d,
J = 5.9 Hz, 1H), 1.27–1.20 (m, 22H), 0.88 (t, J = 6.7 Hz, 3H), 0.18 (s,
9H). 13C NMR (75 MHz, CDCl3): d 134.3, 129.91, 129.86, 128.7,
105.0, 90.6, 63.4, 31.9, 31.8, 29.8, 29.7, 29.6, 29.53, 29.46, 29.3,
29.2, 29.0, 28.9, 27.2, 22.6, 14.1, À0.2. (One resonance was not
observed due to overlapping.) HRMS (ESI-TOF) calcd for
[M+NH4]+ C25H50NOSi 408.3662, found 408.3657.
(1.35 g, 77% yield for
2 steps) as a
colorless oil. 1H NMR
(300 MHz, CDCl3): d 5.74–5.58 (m, 2H), 4.08 (s, 2H), 2.14 (t,
J = 6.8 Hz, 4H), 2.02 (dd, J = 13.0, 6.4 Hz, 2H), 1.47–1.28 (m, 23H),
0.89 (t, J = 6.8 Hz, 3H). 13C NMR (75 MHz, CDCl3): d 133.4, 128.8,
80.2, 80.1, 63.8, 32.2, 31.3, 29.44, 29.40, 29.13, 29.11, 28.8, 28.5,
22.5, 18.73, 18.72, 14.0. (Three resonances were not observed
due to overlapping.) HRMS (APCI-TOF) calcd for [M+H]+ C20H37O:
293.2844, found: 293.2845.
4.2.10. (S,4E,15Z)-1-(Trimethylsilyl)docosa-4,15-dien-1-yn-3-yl
3,5-dinitrobenzoate 12
To a stirred solution of 11 (0.078 g, 0.20 mmol), DMAP (2.5 mg,
0.02 mmol) and triethylamine (0.04 mL, 0.30 mmol) in dry CH2Cl2
(5 mL) was added 3,5-dinitrobenzoyl chloride (0.055 g,
0.24 mmol). The reaction mixture was stirred at 25 °C until the
complete loss of 11 was observed by TLC. The reaction solution
was quenched with water (5 mL), and the aqueous phase was
extracted with CH2Cl2 (3 Â 15 mL). The combined organic phases
were washed with saturated brine solution (50 mL), dried over
anhydrous Na2SO4, and concentrated under reduced pressure.
The residue was purified by silica gel chromatography (n-hex-
ane/ethyl acetate 20:1) to afford 12 (0.110 g, 94% yield, 81% ee)
4.2.7. (2E,13Z)-Icosa-2,13-dien-1-ol 9
To a stirred mixture of Ni(OAc)2Á4H2O (0.99 g, 4 mmol) in EtOH
(10 mL) was added NaBH4 (0.15 g, 4 mmol) portionwise at 25 °C.
After being stirred for 30 min, ethylenediamine (0.97 g, 16 mmol)
and enynic alcohol 8 (1.18 g, 4 mmol) were added sequentially.
The reaction mixture was stirred for 4 h under hydrogen