2836
R. Ballini et al.
SHORT PAPER
Anal. Calcd for C30H59NO2: C, 77.36; H, 12.77; N, 3.01. Found: C,
77.59; H, 12.99; N, 2.87.
In conclusion, we have described the first synthesis of the
fatty alcohol 9 in good yield and using simple chemicals,
moreover, our strategy clearly shows how the nitroalkanes
are: (i) able to couple to other long-chain molecules (3
with 4), (ii) versatile molecules (conversion of the nitro
moiety to the hydroxy group, 7 to 9), and (iii) prone to
give good yields, even with long-chain structures.
11-Nitrotriacontane (7)
To a magnetically stirred solution of nitroalkene 6 (115 mg, 0.247
mmol) in CHCl3–i-PrOH (5 mL, 5:1), was added NaBH4 (38 mg, 1
mmol). The mixture was stirred at 40 °C for 3 h, until all the starting
material had disappeared. The excess of NaBH4 was decomposed
carefully with a few drops of 2 N HCl and the product was extracted
with CH2Cl2 (3 × 15 mL). The combined Et2O extracts were washed
with brine, dried (Na2SO4) and the solution evaporated to dryness.
The crude product was purified by flash column chromatography on
silica gel (hexane) to give pure 7 (76 mg, 66%) as a white solid; mp
28–30 °C.
IR spectra were recorded with a Perkin-Elmer 1310 spectrophoto-
meter. The 1H and 13C NMR spectra were recorded in CDCl3 at 200
MHz and 50 MHz, respectively, on a Varian Gemini 200 spectro-
meter. Chemical shifts were recorded relative to internal TMS. MS
were determined with a non-polar capillary column, utilizing elec-
tron impact (EI) at 70 eV. Elemental analyses were performed using
a C, H, N Analyzer Model 185 from Hewlett-Packard 5890 series.
Flash chromatography was performed18 on Merck SiO2 gel (0.040–
0.063 mm) with hexane–EtOAc as eluent.
IR (Nujol): 1550 (s, NO2) cm–1.
1H NMR (CDCl3): d = 0.89 (t, 6 H, J = 6.5 Hz, CH3 at H-1 and 30),
1.00–1.42 (m, 50 H, H-2 to 9, H-13 to 29), 1.55–2.00 (m, 4 H, H-
10, H-12), 4.40–4.52 (m, 1 H, CHNO2).
13C NMR (CDCl3): d = 14.3, 22.9, 26.0, 27.1, 29.2, 29.4, 29.5, 29.6,
29.7, 29.8, 29.9, 30.4, 32.0, 32.1, 34.1, 89.3 (C-11).
1-Nitroicosane (3)
To a solution of 1-bromoicosane 1 (1.041 g, 2.88 mmol) in acetone
(50 mL) at r.t. was added MeI (860 mg, 5.74 mmol). The mixture
was stirred at 30 °C for 5 d and then the solvent was removed in vac-
uo. The residue was mixed with sat. aq NaHSO3 solution (50 mL)
and extracted with Et2O (3 × 50 mL). The combined Et2O extracts
were dried (Na2SO4) and the solvent was removed in vacuo. The
residue was dissolved in anhyd Et2O (30 mL) and AgNO2 (812 mg,
5.28 mmol) was added. After stirring at 30 °C for additional 5 d, the
mixture was concentrated and the residue was subjected to flash
column chromatography on silica gel (cyclohexane–EtOAc, 90:10)
to give the pure nitroicosane 3 (0.707 g, 75%) as a white solid; mp
49–51 °C.
Anal. Calcd for C30H61NO2: C, 77.02; H, 13.14; N, 2.99. Found: C,
76.79; H, 12.88; N, 3.22.
11-Oxytriacontane (8)
To a magnetically stirred solution of the nitroalkane 7 (36 mg, 0.078
mmol) in anhyd THF–hexane (3 mL, 1:1), was added NaH (6 mg,
0.24 mmol). The mixture was stirred at reflux for 1 h, cooled to r.t.
and poured into a solution of 6 M H2SO4 (6 mL) kept at 0 °C under
magnetic stirring. After 30 min, the mixture was extracted with
Et2O (3 × 5 mL), and the combined Et2O extracts were dried and
concentrated. The crude product mixture was purified by flash col-
umn chromatography on silica gel (hexane–EtOAc, 97:3) allowing
the isolation of pure 11-oxytriacotane 8 (14.3 mg, 42%) as a white
solid; mp 72–74 °C.
IR (Nujol): 1560 (s, NO2) cm–1.
1H NMR (CDCl3): d = 0.89 (t, 3 H, J = 6.6 Hz, CH3), 1.15–1.45 (m,
34 H, H-3 to 19), 1.94–2.10 (m, 2 H, H-2), 4.39 (t, 2 H, J = 7.1 Hz,
CH2NO2).
13C NMR (CDCl3): d = 14.4, 22.9, 26.4, 27.6, 29.1, 29.5, 29.6, 29.7,
29.8, 29.9, 32.1, 76.0 (CH2NO2).
IR (Nujol): 1700 (s, C=O) cm–1.
1H NMR (CDCl3): d = 0.88 (t, 6 H, J = 6.6 Hz, CH3 at H-1 and 30),
1.20–1.34 (m, 46 H, H-2 to 8, H-14 to 29), 1.52–1.62 (m, 4 H, H-9,
H-13), 2.37 (t, 4 H, J = 7.4 Hz, H-10, H-12).
Anal. Calcd for C20H41NO2: C, 73.34; H, 12.62; N, 4.28. Found: C,
73.61; H, 12.83; N, 4.05.
13C NMR (CDCl3): d = 14.3, 22.9, 24.1, 29.4, 29.50, 29.53, 29.58,
29.6, 29.71, 29.79, 29.84, 29.88, 29.92, 32.11, 32.15, 43.0, 212.0
(C=O).
EI-MS: m/z = 436 (M+, 4), 296 (99), 207 (36), 185 (27), 170 (100),
97 (25), 71 (38), 57 (52), 41 (35).
11-Nitrotriacont-10-ene (6)
A solution of 1-nitroicosane (3; 128 mg, 0.392 mmol), decyl alde-
hyde (4; 61 mg, 0.392 mmol) and DBU (24 mg, 0.157 mmol) in
THF (10 mL) was kept at r.t. under magnetic stirring for 2 d. Most
of the solvent was then removed under vacuum to give the crude ni-
troalkanol 5 as a white diastereomeric mixture. To a solution of the
crude 5 in anhyd Et2O (5 mL), were added CuCl (0.81 mg, 0.00817
mmol) and DCC (84 mg, 0.409 mmol). The mixture was magneti-
cally stirred and refluxed overnight. The product formed was puri-
fied by flash column chromatography on neutral aluminum oxide
(hexane) to give the nitroalkene 6 (142 mg, 78% from 3) as a E/Z
diastereomeric mixture (E/Z = 40:60).
Anal. Calcd for C30H60O: C, 82.49; H, 13.85. Found: C, 82.87; H,
14.07.
11-Triacontanol (9)
To a solution of 11-oxytriacotane (8; 28 mg, 64 mmol) in EtOH (2
mL) at r.t. was added NaBH4 (2.4 mg, 64 mmol). The mixture was
stirred at 30 °C for 30 min, then 2 N HCl (2 mL) was added careful-
ly and the mixture was left for 30 min under magnetic stirring. Fi-
nally the mixture was extracted with CH2Cl2 (3 × 5 mL) and the
combined extracts were dried (Na2SO4) and concentrated to give
pure 9 (27.5 mg, 98%) as a white solid; mp 81–83 °C.
IR (Nujol): 1650 (m, C=C), 1520 (s, NO2) cm–1.
1H NMR (CDCl3): d [diastereomeric mixture (E/Z = 40:60)] = 0.88
(t, 6 H, J = 6.4 Hz, CH3 at H-1 and H-30), 0.98–2.00 (m, 46 H, H-2
to -8, H-14 to -29), 2.15–2.41 (m, 2 H, H-13), 2.46–2.63 (m, 2 H,
H-9), 3.13–3.26 (m, 2 H, H-12), 5.67 (t, 0.6 H, J = 7.5 Hz, H-10 Z),
7.09 (t, 0.4 H, J = 8.1 Hz, H-10 E).
IR (Nujol): 3260 (m, OH) cm–1.
1H NMR (CDCl3): d = 0.88 (t, 6 H, J = 6.8 Hz, CH3 at H-1 and H-
30), 1.13–1.23 (m, 50 H, H-2 to 9, H-13 to 29), 1.36–1.48 (m, 4 H,
H-10, H-12), 1.62–1.73 (m, 1 H, OH), 3.55–3.62 (m, 1 H, CHOH).
13C NMR (CDCl3): d [diastereomeric mixture (E/Z = 40:60)] =
14.2, 17.3, 22.87, 22.90, 24.9, 25.6, 26.5, 27.1, 27.4, 28.1, 28.2,
28.5, 28.7, 28.9, 29.1, 29.4, 29.47, 29.55, 29.66, 29.69, 29.7, 29.9,
30.4, 32.07, 32.14, 32.9, 35.1, 43.7 (C-12 E), 56.0 (C-12 Z), 132.0
(C-10 E), 136.6 (C-10 Z), 151.5 (C-11 E), 152.1 (C-11 Z).
13C NMR (CDCl3): d = 14.4, 22.9, 25.9, 27.11, 27.13, 29.57, 29.58,
29.60, 29.85, 29.87, 29.90, 29.91, 29.94, 30.38, 32.14, 32.16, 37.7,
43.7, 72.2 (C-11).
Synthesis 2005, No. 17, 2835–2837 © Thieme Stuttgart · New York