5496
D. Pempo et al. / Tetrahedron 56 (2000) 5493±5497
was added Wilkinson catalyst (100 mg, 13% w/w) and
submitted to hydrogen atmosphere. After 3 h, Wilkinson
catalyst (100 mg, 13% w/w) was again added. The reaction
mixture was stirred at room temperature for 18 h under
hydrogen atmosphere. After concentration, the crude
product was puri®ed by ¯ash chromatography on silica gel
to give 5 (740 mg, 89% yield). Rf0.40 (diethyl ether/
pentane: 1/1). IR (®lm): 3353, 2923, 2855, 1465, 1095,
2608C, n-butyllithium (0.62 mL, 1 mmol, 1.6 M in
hexane). The orange solution of ylide was slowly warmed
to room temperature and stirred for 2 h. After cooling to
2808C, the aldehyde 8 (717 mg, 1.6 mmol) (previously
dried by three azeotropic distillations with benzene) was
added. The reaction mixture was then allowed to warm to
room temperature, quenched by saturated solution of
ammonium chloride (15 mL), water (10 mL), petroleum
ether (10 mL) and extracted with diethyl ether (3£10 mL).
The combined organic layers were washed with brine
(3£10 mL) and dried over magnesium sulfate. After
concentration, the crude product was puri®ed by ¯ash
chromatography to give 9 (132 mg, 21% yield) as a 1/1
mixture of diastereoisomers. Rf0.55 (diethyl ether/petro-
leum ether: 1/4). IR (®lm): 2922, 2852, 1599, 1495, 1462,
1366, 1305, 1187, 1176, 1119, 1097, 1020, 967, 894, 814,
723, 688, 665. 1H NMR d: 0.68±0.98 (12H, m); 1.00±1.43
(40H, m); 1.43±1.74 (4H, m); 1.74±2.14 (4H, m); 2.41 (3H,
s); 4.52±4.75 (1H, m); 5.22±5.39 (2H, m); 7.59 (2H, d,
J7.9 Hz); 7.77 (2H, d, J8.1 Hz). 13C NMR d: 14.2
(2C), 19.6; 19.3; 21.7; 22.8; 22.7; 24.7; 25.0 (2C); 28.7;
29.4±29.8 (10C); 32.1; 31.9; 33.1; 34.4; 34.6; 36.8; 36.9;
41.8; 82.9; 127.8 (2C); 129.6; 129.8; 135.0; 144.2; mean-
ingful signals for the other diastereoisomer: 29.1; 35.1;
37.3; 83.0; 129.7; 130.3; 135.1; 144.3.
1
1049, 956, 845. H NMR d: 0.76±1.05 (6H, m); 1.00±
1.40 (19H, bs); 1.42±1.68 (2H, m); 3.50 (2H, td, J4.0;
5.3 Hz). 13C NMR d14.1; 19.7; 22.7; 27.0; 29.2; 29.3;
29.4 (3C); 30.2; 32.1; 37.3; 39.4; 61.2. Anal. Calcd for
C14H30O: C, 78.4; H, 14.1. Found: C, 78.29; H, 14.02.
(S)-1-Bromo-3-methyltridecane (6). To a mixture of 5
(740 mg, 3.5 mmol) and carbon tetrabromide (1.7 g,
5.2 mmol) in anhydrous dichloromethane (18 mL) was
added, at 08C, triphenylphosphine (1.36 g, 5.2 mmol). The
reaction mixture was slowly allowed to warm to room
temperature. The reaction was monitored by TLC. After
3 h, the reaction mixture was concentrated and puri®ed by
¯ash chromatography on silica gel to give 6 (886 mg, 92%
yield). Rf0.73 (diethyl ether/petroleum ether: 1/1). IR
1
(®lm): 2985, 2873, 1456, 1260, 1215, 721. H NMR d:
0.84±0.87 (6H, m); 1.10±1.36 (19H, bs); 1.58±1.70 (2H,
m); 3.31±3.47 (2H, m). 13C NMR d: 14.4; 19.0; 22.8; 27.1;
29.3; 29.5 (3C); 29.7; 31.4; 32.0; 33.5; 36.9; 41.1. Anal.
Calcd for C14H29Br: C, 60.6; H, 10.5. Found: C, 60.35; H,
10.34.
(11S,17R)-11,17-Dimethylhentriacont-13-ene (10). To a
suspension of lithium aluminium hydride (10 mg,
0.2 mmol) in anhydrous diethyl ether (10 mL), 9 (132 mg,
0.2 mmol) was added. After stirring for 10 h at room
temperature, the reaction was monitored by TLC. The reac-
tion was quenched by 3 mL of ethanol, ®ltered on celite 545
and alkene 10 (55 mg, 93% yield) was obtained after
concentration. Rf0.77 (diethyl ether/petroleum ether:
(S)-3-Methyltridecyltriphenylphosphonium bromide (7).
To a solution of 6 (871 mg, 3.2 mmol) in acetonitrile
(31 mL) was added triphenylphosphine (1 g, 3.7 mmol).
After re¯uxing for 48 h, the reaction mixture was concen-
trated and the crude material was chromatographed on silica
gel giving 7 (1.5 g, 91% yield). Rf0.26 (5% methanol/
dichloromethane). IR (®lm): 3053, 2923, 2854, 1483,
1
1/10). IR (®lm): 3026, 2952, 2860, 1475, 1326. H NMR
d: 0.60±0.91 (12H, m); 0.91±1.54 (48H, m); 1.65±2.11
(4H, m); 5.14±5.48 (2H, m). 13C NMR d: 14.2 (2C); 19.6;
19.7; 22.7; 22.8; 25.0; 27.2; 27.3; 29.1±30.3 (14C); 31.9;
32.0; 33.1; 32.5; 34.5; 36.8; 37.1 (2C); 129.8; 131.0. Anal.
Calcd for C33H66: C, 85.6; H, 14.4;. Found: C, 85.84; H,
14.22.
1
1437, 1271, 1190, 1114, 996. H NMR d: 0.73±0.90 (3H,
m); 0.90±1.06 (19H, bs); 1.13±1.40 (11H, m); 1.50±1.71
(2H,m); 3.70±3.86 (2H, m); 7.63±7.93 (15H, m); 13C NMR
d: 13.9; 19.3; 20.5 (1C, d, JCP50.0 Hz); 22.7; 24.5; 27.4±
28.8 (4C); 29.6 (1C, d, JCP5.5 Hz); 31.7 (2C); 33.0 (1C, d,
JCP15.0 Hz); 35.9; 118.5 (3C, d, JCP85.0 Hz); 130.9 (6C,
d, JCP12.5 Hz); 133.5 (6C, d, JCP10.2 Hz); 135.3 (3C, d,
JCP3.3 Hz).
(11S,17R)-11,17-Dimethyl-13,14-ditritiohentriacontane
(1). To a solution of the alkene 10 (25 mg, 0.054 mmol) in
diethyl ether (5 mL), was added the Wilkinson catalyst
(30 mg). The ¯ask was connected to a Toppler ramp tritium
mannifold in a glove compartment then frozen with liquid
nitrogen and degassed under vacuum during a minute
approximately. The mixture was then placed under a tritium
atmosphere and slowly warmed to room temperature with a
control of the absorption of tritium. The tritium uptaken was
monitored and a constant pressure of 1 atm tritium was
maintained within the reaction vessel. After 16 h at this
temperature, the reaction was stopped by ®ltration on Millex
®lter. The ¯ask and the ®lter were washed and rinsed with
dichloromethane (2£20 mL), then the organic layers are
concentrated, the crude mixture was then diluted with
50 mL of MeOH and the labile tritium is removed. The
crude mixture obtained is ®ltered on silica gel (eluent: pen-
tane) then puri®ed by HPLC using a C18 Nucleosil column
eluting with a mixture of acetone/methanol/H2O (95/2.5/
2.5). radiochemical yield .95%. Speci®c activity52 Ci/
mmole as determined by MS. 1H NMR d: 0.79±0.88 (12H,
(S)-4-Methyl-6-( p-toluenesulfonyloxy)octadecanal (8).
Compound 8 was prepared in three steps from (S)-citronellal
according to Ref. 8. IR (®lm): 2925, 2855, 1724, 1461,
1
1359, 1177, 1097, 897, 737. H NMR d: 0.70±1.00 (6H,
m); 1.00±1.70 (27H, m); 2. 22±2.44 (2H, m); 2.42 (3H,
s);4.52±4.70 (1H, m); 7.28±7.32 (2H, d, J8.2 Hz);
7.74±7.78 (2H, d, J8.1 Hz); 9.70 (1H, t, J1.6 Hz). 13C
NMR d: 14.2; 19.6; 21.6; 22.7; 24.6; 28.3; 28.7; 29.4 (3C);
29.5; 29.7 (3C); 32.0; 35.0; 41.4; 41.6; 82.6; 127.8 (2C);
129.7 (2C); 134.7; 144.5; 202.2; meaningful signals for the
other diastereoisomer: 19.0; 24.5; 28.6; 34.4;41.3; 41.5;
82.4; 202.3.
(11S,17S)-11,17-Dimethyl-19-( p-toluenesulfonyloxy)-
hentriacont-13-ene (9). To a suspension of 7 (500 mg,
0.9 mmol) (previously dried by three azeotropic distillations
with benzene) in tetrahydrofuran (12 mL) was added, at