128.48, 137.8, 138.1; MS (EI) m/z 273, 261, 247, 233, 192, 183,
157, 91. Anal. Calcd for C25H36O4: C, 74.96; H, 9.06. Found: C,
74.90; H, 9.00.
3.1-3.2 (br s, 2H), 3.52 (s, 4H); 13C NMR (125 MHz, CDCl3) δ
7.5, 26.8, 35.9, 41.8, 67.9; MS (EI) m/z 186, 185, 169, 155, 154,
151, 139, 111. Anal. Calcd for C13H28O2: C, 72.17; H, 13.04.
Found: C, 72.03; H, 12.79.
3,5-Bis(benzyloxymethyl)-3,5-diethyl-1,6-heptadiene (16). Ox-
alyl chloride (0.7 mL, 8 mmol, 4 equiv) was mixed with dry DCM
(30 mL) under N2 and cooled to -78 °C. To this stirred solution
was added anhydrous DMSO (1.13 mL, 16 mmol, 8 equiv) slowly
over 5 min. After stirring for 20 min, a solution of diol 15 (800
mg, 2 mmol, 1 equiv) in dry DCM (5 mL) was added slowly over
5 min. The mixture was stirred at -78 °C for 1 h before Et3N (4.5
mL, 32 mmol, 16 equiv) was introduced. The reaction mixture was
raised to rt gradually over 2 h, then washed with water (2 × 10
mL) and brine (10 mL), dried (Na2SO4), and concentrated under
vacuum to afford an oily residue. Purification by chromatography
(eluent: hexane/ethyl acetate 20:1 with 1% Et3N) on silica gel gave
the aldehyde (700 mg, 87.5%) as an oil, which was used
immediately: 1H NMR (500 MHz, CDCl3) δ 0.72 (t, J ) 7.5 Hz,
6H), 1.50-1.60 (m, 2H), 1.60-1.80 (m, 2H), 1.99 (s, 2H), 3.40
(d, J ) 10 Hz, 2H), 3.53 (d, J ) 10 Hz, 2H), 4.21 (d, J ) 11.5 Hz,
2H), 4.38 (d, J ) 11.5 Hz, 2H), 7.30 (m, 10H), 9.27 (s, 2H); 13C
NMR (125 MHz, CDCl3) δ 7.8, 27.2, 36.3, 53.2, 66.5, 72.7, 127.7,
127.9, 128.4, 137.9, 204.5. A solution of KHMDS (3.8 mL 0.5 M,
1.9 mmol, 3 equiv) in toluene was added slowly to a stirred
suspension of methyltriphenylphosphonium bromide (674 mg 1.89
mmol, 3 equiv) in dry THF (15 mL) at -78 °C under N2 over 5
min. The reaction mixture was raised to rt gradually to give a yellow
solution, then cooled to -78 °C, before the above dialdehyde (250
mg, 0.63 mmol, 1 equiv) in dry THF (5 mL) was added. The
reaction mixture was stirred overnight, and the resulting solution
was filtered through a silica gel pad, washing with 5% ethyl acetate
in hexane, and the filtrate was concentrated under vacuum to give
a residue. Purification by silica gel chromatography (eluent: hexane/
ethyl acetate 20:1) afforded 16 (230 mg, 93%) as an oil. 1H NMR
(500 MHz, CDCl3) δ (major, dl) 0.69 (t, J ) 7.5 Hz, 6H), 1.29 (m,
2H), 1.59 (m, 2H), 1.65 (s, 2H), 3.35 (d, J ) 9.0 Hz, 2H), 3.55 (d,
J ) 9.0 Hz, 2H), 4.40 (d, J ) 12.0 Hz, 2H), 4.48 (d, J ) 12.0 Hz,
2H), 4.74 (dd, J ) 18, 1.5 Hz, 2H), 4.90 (dd, J ) 11, 1.5 Hz, 2H),
5.78 (dd, J ) 18, 11 Hz, 2H), 7.20-7.40 (m, 10H); (minor, meso)
0.73 (t, J ) 7.5 Hz, 6H), 1.45 (m, 2H), 1.48 (d, J ) 15 Hz, 1H),
1.60 (m, 2H), 1.76 (d, J ) 15 Hz, 1H), 3.31 (d, J ) 9 Hz, 2H),
3.80 (d, J ) 9 Hz, 2H), 4.42 (d, J ) 12 Hz, 2H), 4.46 (d, J ) 12
Hz, 2H), 4.84 (dd, J ) 18, 1.5 Hz, 2H), 4.96 (dd, J ) 11, 1.5 Hz,
2H), 5.79 (dd, J ) 18, 11 Hz, 2H), 7.20-7.40 (m, 10H); 13C NMR
(125 MHz, CDCl3) δ 7.7, 7.9, 29.0, 31.0, 41.2, 43.2, 44.1, 44.2,
71.1, 72.7, 73.0, 73.3, 111.1, 111.9, 127.3, 127.5, 128.2, 139.0,
145.2, 145.3; MS (EI) m/z 293, 292, 278, 264, 250, 208,125, 97.
Anal. Calcd for C27H36O2: C, 82.61; H, 9.24. Found: C, 82.61; H,
9.26.
5,5,7,7-Tetraethylundeca-3,8-diene (18). Diol 17 (260 mg, 1.2
mmol) was converted to the corresponding dialdehyde by Swerm
oxidation following the same procedure as for the oxidation of 15.
The crude product was purified by silica gel chromatography
(eluent: hexane/ethyl acetate 20:1 with 1% Et3N) to give the
dialdehyde (221 mg yield 87%) as an oil, which was used
immediately: 1H NMR (500 MHz, CDCl3) δ 0.76 (t, J ) 7.5 Hz,
12H), 1.36 (q, J ) 7.5 Hz, 4H), 1.61 (q, J ) 7.5, 4H), 1.78 (s,
2H), 9.48 (s, 2H); 13C NMR (125 MHz, CDCl3) δ 7.5, 23.8, 28.5,
52.3, 206.3. This dialdehyde (221 mg) was subjected to a Wittig
reaction with propylidene triphenylphosphorane following the
procedure used in the preparation of 16. The crude product was
purified by silica gel chromatography (eluent: hexane) to afford
the diene 18 (180 mg, 65%) as an oil: 1H NMR (500 MHz, CDCl3)
δ 0.74 (t, J ) 7.5 Hz, 12H), 0.96 (t, J ) 7.5 Hz, 6H), 1.40-1.50
(m, 4H), 1.50-1.60 (m, 6H), 2.10-2.20 (m, 4H), 5.11 (m, 3H);
13C NMR (125 MHz, CDCl3) δ 8.3, 14.7, 22.3, 30.0, 43.9, 45.4,
130.5, 138.1; MS (EI) m/z 236, 235, 221, 207, 193, 151, 125, 83.
Anal. Calcd for C19H36: C, 86.28; H, 13.72. Found: C, 86.30; H,
13.75.
5,5,7,7-Tetraethylundecane (19). Diene 18 (180 mg, 0.68 mmol)
was hydrogenated, by the procedure used in the reduction of alkene
10, to give alkane 19 (178 mg, 97.5%) as an oil: 1H NMR (500
MHz, CDCl3) δ 0.77 (t, J ) 7.5 Hz, 12H), 0.90 (t, J ) 7.0 Hz,
6H), 1.12 (s, 2H), 1.13-1.21 (m, 4H), 1.21-1.29 (m, 8H), 1.32
(q, J ) 7.5 Hz, 8H); 13C NMR (125 MHz, CDCl3) δ 8.1, 14.3,
23.8, 25.7, 29.6, 36.7, 37.0, 39.6; MS (EI) m/z 239, 127, 126, 117,
96, 86, 71, 57. Anal. Calcd for C19H40: C, 84.99; H, 15.01.
Found: C, 85.25; H, 15.27.
Mass Spectrometry. Samples were injected at 60 °C onto a HP-
5MS capillary column (30 m × 0.25 mm × 0.25 µm). After a 1.5
min hold time, the oven temperature was ramped to 130 °C at 20
deg/min and then to 315 °C at 4 deg/min, using He as carrier gas.
The eluent was examined with a mass sensitive detector operating
in the EI mode at 70 eV, scanning a mass range of m/z 40-650 at
2.44 scans per second.
Coelution Experiments. Samples were injected in the conditions
described above for mass spectrometry and were injected as well
on a DB-1 capillary column (60 m × 0.25 mm × 1 µm) installed
in a HP 5890 gas chromatogram coupled to an FID detector.
Acknowledgment. This research was supported in part by
NASA-Exobiology EXB02-0000-0017 and a University of
Illinois at Chicago Campus Research Board grant (F.K.).
2,2,4,4-Tetraethylpentane-1,5-diol (17). Diene 16 (200 mg, 0.51
mmol) was dissolved in ethyl acetate (10 mL), treated with 10%
Pd/C (10 mg), and stirred under 1 atm of H2 overnight. After
filtration of the catalyst, the reaction mixture was concentrated to
give diol 17 (109 mg, 99%) as an oil: 1H NMR (500 MHz, CDCl3)
δ 0.79 (t, J ) 7.5 Hz, 12H), 1.25 (s, 2H), 1.26-1.40 (m, 8H),
Supporting Information Available: Details of the preparation
of 1-13, NMR spectra of all compounds, 70 eV EI mass spectra,
and GC data of the synthetic and isolated BAQC’s. This material
JO0603983
J. Org. Chem, Vol. 71, No. 13, 2006 5019