A. Fu¨rstner, G. Seidel / Journal of Organometallic Chemistry 606 (2000) 75–78
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3.2. Preparation of 2,19-heneicosadiyn-11-ol (3)
50/130/1) affording cycloalkyne 5 as a colorless
syrup (299 mg, 65%). 1H-NMR (300 MHz, CDCl3):
l=2.41 (t, J=6.9, 4H), 2.17 (m, 4H), 1.65 (m, 4H),
1.44 (m, 8H), 1.32 (m, 8H). 13C-NMR (75 MHz,
CDCl3): l=212.9, 80.5, 42.3, 28.7, 28.6, 28.2, 27.9,
24.0, 18.5. MS: m/z (rel. intensity): 248 ([M+], 11), 230
(3), 219 (5), 205 (5), 193 (7), 179 (6), 166 (19), 151 (11),
135 (16), 121 (27), 107 (32), 93 (47), 81 (65), 79 (64), 67
(74), 55 (79), 41 (100). IR (neat): 2928, 2856, 1710,
1460, 1437, 1357, 1331, 1276, 1113, 1053, 722. Anal.
Calc. (C17H28O): C, 82.20; H, 11.36. Found: 82.35; H,
11.20. A second more polar fraction was eluated which
consists of the cyclodimeric product cyclotetratriacont-
9,26-diyn-1,18-dione (20 mg, 4%) exhibiting the follow-
ing spectroscopic properties: 1H-NMR (300 MHz,
CDCl3): l=2.40 (t, J=7.3, 8H), 2.14 (m, 8H), 1.57 (m,
8H), 1.43 (m, 16H), 1.30 (m, 16H). 13C-NMR (75 MHz,
CDCl3): l=211.5, 80.3, 42.7, 29.2, 28.83, 28.75, 28.4,
23.8, 18.6. MS: m/z (rel. intensity): 496 ([M+], 35), 478
(5), 413 (4), 355 (3), 315 (4), 301 (6), 287 (5), 233 (2),
187 (3), 165 (11), 147 (13), 135 (17), 121 (29),107 (31),
95 (56), 81 (81), 67 (89), 55 (100), 41 (54).
A solution of aldehyde 1 (3.33 g, 20 mmol) in THF
(50 ml) is added dropwise over a period of 1 h to a
solution of 8-decynylmagnesium bromide 2 (0.14 M in
THF, 142 ml, 21 mmol) at −30°C. Once the addition
is complete, the reaction mixture is stirred at ambient
temperature for 10 h. Standard extractive work-up
using tert-butyl methylether for the extraction of the
aqueous phase followed by flash chromatography (hex-
ane–ethyl acetate, 30/110/1) of the crude material
provides alcohol 3 as colorless crystals (3.50 g, 58%).
m.p.=60–61°C. 1H-NMR (300 MHz, CDCl3): l=
3.58 (m, 1H), 2.11 (tq, J=6.8, 2.6, 4H), 1.78 (t, J=2.6,
6H), 1.55–1.2 (m, 24 H).13C-NMR (75 MHz, CDCl3):
l=79.3, 75.3, 71.9, 37.4, 29.5, 29.1, 29.0, 28.8, 25.6,
18.7, 3.4. MS: m/z (rel. intensity): 304 ([M+], B1), 271
(4), 257 (3), 243 (1), 229 (1), 201 (2), 189 (2), 175 (5),
161 (10), 149 (30), 135 (23), 121 (30), 107 (45), 95 (63),
81 (92), 67 (74), 55 (100), 41 (59). IR (neat): 3322, 3238,
2929, 2849, 1509, 1463, 1427, 1146, 1121, 1067, 1049,
1005, 925, 866, 812, 724, 665.
3.3. Preparation of 2,19-heneicosadiyn-11-one (4)
3.4.2. Method B
PDC (6.50 g, 17 mmol) is added in portions to a
solution of alcohol 3 (3.40 g, 11 mmol) in CH2Cl2 (300
ml) and the resulting suspension is stirred for 16 h at
ambient temperature. Filtration of the mixture through
a short pad of silica, thorough washing of the insoluble
residues with CH2Cl2 (200 ml in several portions) and
evaporation of the combined filtrates affords analyti-
cally pure ketone 4 as colorless crystals (3.03 g, 91%).
m.p.=55–56°C. 1H-NMR (300 MHz, CDCl3): l=
2.38 (t, J=7.5, 4H), 2.11 (tq, J=6.8, 2.6, 4H), 1.77 (t,
J=2.6, 6H), 1.56 (m, 4H), 1.22–1.50 (m, 16H). 13C-
NMR (75 MHz, CDCl3): l=211.5, 79.2, 75.3, 42.7,
29.1, 29.0, 28.9, 28.6, 23.8, 18.6, 3.4. MS: m/z (rel.
intensity): 302 ([M+], 2), 287 (3), 273 (5), 165 (23), 147
(21), 133 (15), 122 (42), 107 (33), 95 (62), 81 (100), 67
(66), 55 (73), 41 (60). IR (neat): 2929, 2850, 1700, 1470,
1421, 1385, 1253, 1113, 1060, 717. Anal. Calc.
(C21H34O): C, 83.40; H, 11.33. Found: C, 82.89; H,
11.44.
A solution of diyne 4 (369 mg, 1.2 mmol), Mo(CO)6
(16 mg, 5 mol%) and p-trifluoromethylphenol (198 mg,
1.2 mmol) in chlorobenzene (150 ml) is stirred for 7 h at
130–140°C. During this time, a gentle stream of argon
is bubbled through the reaction mixture. Evaporation
of the solvent at reduced pressure (ca. 10 mbar) fol-
lowed by chromatographic purification of the residue
(hexane–ethyl acetate, 50/1) affords the title compound
as a colorless syrup (180 mg, 59%).
3.5. Preparation of ci6etone (6)
A suspension of cycloalkyne 5 (169 mg, 0.68 mmol),
quinoline (40 ml) and Lindlar catalyst (40 mg) in
CH2Cl2 (50 ml) is stirred under an atmosphere of H2 (1
atm.) for 2 h at ambient temperature. The catalyst is
filtered off through a short pad of silica, the solvent is
evaporated and the crude product is purified by flash
chromatography (hexane–ethyl acetate, 50/1) affording
compound 6 as a colorless syrup which slowly crystal-
lizes upon standing to afford a waxy solid (159 mg,
94%). 1H-NMR (300 MHz, CDCl3): l=5.34 (ddd,
J=5.9, 4.5, 1.1, 2H), 2.39 (t, J=6.8, 4H), 2.01 (dt,
J=6.4, 5.9, 4H), 1.62 (m, 4H), 1.29 (m, 16 H). 13C-
NMR (75 MHz, CDCl3): l=212.4, 130.1, 42.4, 29.0,
28.6, 28.2, 28.1, 26.6, 23.8. MS: m/z (rel. intensity): 250
([M+], 95), 232 (4), 221 (2), 207 (2), 149 (5), 135 (11),
121 (14), 109 (19), 95 (37), 81 (53), 67 (63), 55 (94), 41
(100). IR (neat): 3003, 2925, 2853, 1711, 1654, 1460,
1409, 1364, 1275, 1124, 1056, 719.
3.4. Preparation of cycloheptadec-9-yn-1-one (5) by
ring closing alkyne metathesis
3.4.1. Method A
A solution of diyne 4 (556 mg, 1.80 mmol) and
(t-BuO)3WꢀCCMe3 (85 mg, 10 mol%) in toluene (300
ml) is stirred at 80°C for 30 min. The reaction mixture
is filtered through a pad of silica, the insoluble residues
are carefully washed with CH2Cl2 (100 ml in several
portions), the combined filtrates are evaporated and
the residue is chromatographed (hexane–ethyl acetate,