PAPER
Further Improvements of the Synthesis of Alkynes from Aldehydes
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mmol) in MeCN (15 mL). The mixture was stirred for 2 h. Then the
aldehyde 4 (1.0 mmol), dissolved in MeOH (3 mL), was added. Stir-
ring was continued for 8 h. The solvents were removed in vacuo and
the residue was dissolved in Et2O (10 mL) and water (10 mL). The
aq layer was separated and the organic layer was washed with water
(5 mL), brine (5 mL) and dried over anhyd Na2SO4. The solvent was
removed in vacuo and the residue was triturated with n-pentane (5
mL) and decanted from insoluble material (3–7 times, depending on
the solubility of the alkyne). After removal of the solvent the alkyne
5 remained in analytically pure form.
(+)-(4E)-Tricarbonyl[(4-7- 4)-3,3,6-trimethylhepta-4,6-dien-1-
yne]-iron(0) (5e)17
Yield: 183 mg (68%) [Method A], 188 mg (70%) [Method B];17 yel-
low oil.
IR (neat): 3300, 2970, 2920, 2040, 1970, 1730, 1260 cm–1 (lit.17
2040 cm–1).
1H NMR (400 MHz, CDCl3): = 0.20 (d, J = 2.4 Hz, 1 H, Hen-7),
0.69 (d, J = 8.5 Hz, 1 H, H-4), 1.38 (s, 6 H, 3-CH3), 1.73 (d, J = 2.4
Hz, 1 H, Hex-7), 2.20 (s, 3 H, 6-CH3), 2.26 (s, 1 H, H-1), 5.54 (d,
J = 8.3 Hz, 1 H, H-5).
Method B; General Procedure
(3S)-(–)-3-(para-Methoxybenzyloxy)-oct-1-yne (5f)
Yield: 180 mg (73%) [Method A], 197 mg (80%) [Method B]; col-
orless oil; [ ]D –87.2 (c 2.08, CHCl3).
IR (neat): 3300, 2960, 2920, 2870, 2090, 1600, 1580 cm–1.
1H NMR (400 MHz, CDCl3): = 0.88 (t, J = 6.5 Hz, 3 H, CH3),
1.24–1.43 (m, 6 H, CH2), 1.70 (m, 2 H, CH2), 2.45 (s, 1 H, ≡CH),
3.80 (s, 3 H, OCH3), 4.05 (m, 1 H, CH-O), 4.58 (dd, J = 11.4 Hz, 2
H, OCH2-Ar), 6.87 (d, J = 8.3 Hz, 2 H, CHar), 7.28 (d, J = 8.3 Hz, 2
H, CHar).
13C NMR (100 MHz, CDCl3): = 15.0 (CH3), 23.5, 25.8, 32.4, 36.6
(CH2), 56.2 (OCH3), 69.0 (CH-C), 71.0 (OCH2), 74.6 (CH), 84.1
(CCH), 114.7, 130.6 (Car), 130.9, 160.2 (COO) ppm.
Dimethyl-1-diazo-2-oxopropylphosphonate 2 (1.2 mmol) was add-
ed to a solution of aldehyde 4 (1.0 mmol) and K2CO3 (2.0 mmol) in
MeOH (15 mL) and stirring was continued for 8 h. The reaction
mixture was diluted with Et2O (25 mL), washed with an aq solution
(5%) of NaHCO3 (10 mL) and dried over Na2SO4. After filtration
and evaporation of the solvent in vacuo the alkyne 5 remained in an-
alytically pure form.
Tridec-1-yne (5a)21
Yield: 160 mg (89%) [Method A], 172 mg (96%) [Method B]; col-
orless liquid.
IR (neat): 3320, 2120 cm–1 (lit.21 3320 cm–1).
1H NMR (400 MHz, CDCl3): = 0.88 (t, J = 7.0 Hz, 3 H, CH3),
1.26–1.56 (m, 18 H, CH2), 1.93 (t, J = 3.0 Hz, 1 H, ≡CH), 2.18 (dt,
J1 = 7.0 Hz, J2 = 3.0 Hz, 2 H, ≡C-CH2).
EI–MS: m/z = 246 [M+], 121.
Anal. Calcd for C16H22O2 (246.36): C, 78.01; H, 9.00. Found: C,
78.03; H, 9.11.
4-Chlorophenylacetylene (5b)22
Yield: 112 mg (83%) [Method A], 131 mg (97%) [Method B]; col-
orless crystals; mp 45 °C (lit.22 45 °C).
Acknowledgment
IR (KBr): 3295, 2956, 2109, 1488 cm–1.
1H NMR (400 MHz, CDCl3): = 3.10 (s, 1 H, ≡CH), 7.29 (d, J =
9.0 Hz, 2 H, CHar), 7.41 (d, J = 9.0 Hz, 2 H, CHar).
We thank Prof. K. Hafner for the kind donation of a sample of alde-
hyde 4g. We thank J. Böhmer for kind donation of a sample of al-
dehyde 4e.
13C NMR (100 MHz, CDCl3): = 78.2 (CH), 82.5 (C-), 120.6 (C-
Car), 128.7, 133.4 (CHar), 134.9 (CarCl).
References
(1) New address: Boehringer Ingelheim Pharma GmbH & Co.
KG, Chemical Research, Birkendorfer Str. 65, 88397
Biberach/Riss, Germany.
(2) New address: Abbott GmbH & Co. KG, Knollstr., 67061
Ludwigshafen, Germany.
(3) (a) Seyferth, D.; Marmor, R. S.; Hilbert, P. J. Org. Chem.
1971, 36, 1379. (b) Lewis, R. T.; Motherwell, B. T.
Tetrahedron 1992, 48, 1465. (c) Brown, D. G.; Velthuisen,
E. J.; Commerford, J. R.; Brisbois, R. G.; Hoye, T. R. J. Org.
Chem. 1996, 61, 2540.
(4) (a) Gilbert, J. C.; Weerasoriya, U. J. Org. Chem. 1979, 44,
4997. (b) Gilbert, J. C.; Weerasoriya, U. J. Org. Chem. 1982,
47, 1837.
(5) Corey, E. J.; Fuchs, P. L. Tetrahedron Lett. 1972, 3769.
(6) (a) Köbrich, G.; Trapp, H.; Flory, K.; Drischel, W. Chem.
Ber. 1966, 99, 689. (b) Bestmann, H. J.; Frey, H. Liebigs
Ann. Chem. 1980, 2061. (c) Corey, E. J.; Achiwa, K.;
Katzenellenbogen, J. A. J. Am. Chem. Soc. 1969, 91, 4318.
(d) Matsumoto, M.; Kuroda, K. Tetrahedron Lett. 1980, 21,
4021. (e) Bestmann, H. J.; Rippel, H.; Dostalek, R.
Tetrahedron Lett. 1989, 30, 5261.
4,8-Dimethylnon-7-en-1-yne (5c)23
Yield: 109 mg (72%) [Method A], 145 mg (96%) [Method B]; col-
orless liquid.
IR (neat): 3310, 2980, 2950, 2850, 2110, 1450 cm–1 (lit.23 3313
cm–1).
1H NMR (400 MHz, CDCl3): = 0.99 (d, J = 6.0 Hz, 3 H, CH-CH3),
1.25 (m, 1 H, CH2), 1.45 (m, 1 H, CH2), 1.61 (s, 3 H, =CH-CH3),
1.65 (m, 1 H, CH2), 1.68 (s, 3 H, =CH-CH3), 1.94 (t, J = 3.0 Hz, 1
H, ≡CH), 1.98–2.20 (m, 4 H, CH2, CHH, CH), 5.10 (t, J = 7 Hz, 1
H, =CH).
(4S,5R)-(–)-2,2-Dimethyl-4-ethinyl-5-methoxycarbonyl-1,3-di-
oxolane (5d)
Yield:24 107 mg (65%) [Method A], 120 mg (73%) [Method B]; col-
orless oil; [ ]D –57.6 (c 0.67, CHCl3).
IR (neat): 3280, 2995, 2960, 2120, 1760, 1385 cm–1.
1H NMR (400 MHz, CDCl3): = 1.48 (s, 3 H, CH3), 1.56 (s, 3 H,
CH3), 2.61 (d, J = 2.0 Hz, 1 H, CH), 3.82 (s, 3 H, OCH3), 4.62 (d,
J = 5.9 Hz, 1 H, CH-CO), 4.88 (d, J = 5.9 Hz, 1 H, CH-C).
13C NMR (100 MHz, CDCl3): = 26.3 (CH3), 26.5 (CH3), 52.7
(OCH3), 68.4 (CH-C), 75.2 (CH), 79.7 (CH-CO), 80.2 (CCH),
113.1 [C(CH3)2], 169.7 (COO).
(7) For the use of trimethylsilyldiazomethane as reagent, see:
Ohira, S.; Okai, K.; Moritani, T. J. Chem. Soc., Chem.
Commun. 1992, 721; and ref. cited therein.
(8) (a) Regitz, M.; Anschütz, W. Liebigs Ann. Chem. 1969, 730,
194. (b) Regitz, M.; Liedhegener, A.; Eckstein, U.; Martin,
M.; Anschütz, W. Liebigs Ann. Chem. 1971, 748, 207.
(9) Colvin, E. W.; Hamill, B. J. J. Chem. Soc., Perkin Trans. 1
1977, 869.
EI–MS: m/z = 184 [M+], 169.
Anal. Calcd for C9H12O4 (184.21): C, 58.69; H, 6.57. Found: C,
58.83; H, 6.51.
Synthesis 2004, No. 1, 59–62 © Thieme Stuttgart · New York