Butadiyne

(R = H)

[460-12-2]  · C4H2  · Butadiyne  · (MW 50.06) (R = SiMe3)

[4526-07-2]  · C10H18Si2  · 1,4-Bis(trimethylsilyl)buta-1,3-diyne  · (MW 194.42)

(butadiyne is an intermediate for synthesis of substituted 1,3-diynes.1-3 The silylated derivative is used for Friedel-Crafts acylation,5-7 for the synthesis of heterocycles,8-11 and for the preparation of (Z)-methyl-1,4-bis(trimethylsilyl)-1-buten-3-yne derivatives;12 hydrosilation gives access to vinylsilane derivatives;13 trimethylsilylbuta-1,3-diynyllithium may be acylated or alkylated14-17 and used in the synthesis of (Z)- or (E)-enyne derivatives15,18,19)

Physical Data: R = H: mp -36 to -35 °C; bp 10 °C. R = SiMe3: mp 107-108 °C.

Solubility: R = H or SiMe3: sol most organic solvents.

Preparative Methods: R = H: from dehydrochlorination of 1,4-dichloro-2-butyne with sodium or potassium hydroxide.4 R = SiMe3: by dimerization of trimethylsilylacetylene under copper catalysis and in the presence of TMEDA.5

Handling, Storage, and Precautions: R = H: irritant, extremely flammable, and potentially explosive. Readily polymerizes above 0 °C. THF solutions can be stored for at least 3 d at -20 °C; storage of large quantities should be avoided. R = SiMe3: stable white solid.

Alkylation and Acylation Reactions of Butadiyne.

Formation of the mono- or bis-sodium anion of butadiyne can be achieved directly from 1,4-Dichloro-2-butyne with 3 or 4 equiv of sodamide.1,2 This avoids isolation of the highly unstable parent compound. Alkylation or acylation in situ with alkyl halides or carbonyl compounds is then possible (eq 1). The mono- or bis-lithium anion can also be produced in situ by deprotonation and elimination of (Z)-1-methoxybut-1-en-3-yne with either 2 or 3 equiv of n-Butyllithium (eq 2).3

Conjugated Diynones.

1,4-Bis(trimethylsilyl)buta-1,3-diyne has been used in Friedel-Crafts acylation reactions under Lewis acid catalysis (eq 3).5-7

Diels-Alder Reactions.

1,4-Bis(trimethylsilyl)buta-1,3-diyne has been used with varying degrees of success as a dienophile in Diels-Alder cycloadditions (eq 4).8-10

Synthesis of Pyrazoles and Isoxazoles.

1,4-Bis(trimethylsilyl)buta-1,3-diyne has been used for the synthesis of pyrazoles and isoxazoles;11 for example, reaction with Hydrazine gives the indicated pyrazole (eq 5).

(Z)-Methyl-1,4-bis(trimethylsilyl)-1-buten-3-yne Derivatives.

Zirconium catalyzed carbometalation of 1,4-bis(trimethylsilyl)buta-1,3-diyne with Trimethylaluminum followed by addition of electrophiles gives access to the title derivatives (eq 6).12

Vinylsilanes.

Hydrosilation of 1,4-bis(trimethylsilyl)buta-1,3-diyne gives access to a range of vinylsilane derivatives.13

Trimethylsilylbuta-1,3-diynyllithium.

Treatment of 1,4-bis(trimethylsilyl)buta-1,3-diyne with Methyllithium-Lithium Bromide selectively produces trimethylsilylbuta-1,3-diynyllithium (eq 7).14 This reagent combines with various electrophiles to produce substituted 1,3-diynes (e.g eq 8).15-17 The same anion can be synthesized from (Z)-4-trimethylsilyl-1-methoxybut-1-en-3-yne by deprotonation and elimination with 2 equiv of n-BuLi (eq 2).3

Hydrogenation.

Hydrogenation of siladiynes selectively reduces the triple bond which is furthest from the silicon protecting group, yielding silyl protected cis-enynes.16,18 Formation of the corresponding trans-enyne derivatives is possible by hydroalumination.7,17,19


1. Armitage, J. B.; Jones, E. R. H.; Whiting, M. C. JCS 1951, 44. Armitage, J. B.; Jones, E. R. H.; Whiting, M. C. JCS 1952, 1993.
2. Bohlmann, F. CB 1951, 84, 545.
3. Zweifel, G.; Rajagopalan, S. JACS 1985, 107, 700.
4. (a) Johnson, A. W. JCS 1946, 1009. (b) Brandsma, L. Preparative Acetylene Chemistry, 2nd ed.; Elsevier: Amsterdam, 1988; pp 179-181.
5. Jones, G. E.; Kendrick, D. A.; Holmes, A. B. OS 1987, 65, 52 and references therein.
6. Stang, P. J.; Ladika, M. S 1981, 29.
7. Holmes, A. B.; Tabor, A. B.; Baker, R. JCS(P1) 1991, 3307.
8. Birkofer, L.; Hansel, E.; Steigel, A. CB 1982, 115, 2574.
9. Birkofer, L.; Hansel, E. CB 1981, 114, 3154.
10. Liotta, D.; Saindane, M.; Ott, W. TL 1983, 24, 2473.
11. Birkofer, L.; Richtzenhain, K. CB 1979, 112, 2829.
12. Kusumoto, T.; Nishide, K.; Hiyama, T. CL 1985, 1409.
13. Kusumoto, T.; Hiyama, T. CL 1985, 1405.
14. Holmes, A. B.; Jennings-White, C. L. D.; Schulthess, A. H.; Akinde, B.; Walton, D. R. M. CC 1979, 840.
15. Holmes, A. B.; Jones, G. E. TL 1980, 21, 3111.
16. Jones, G. E.; Holmes, A. B. TL 1982, 23, 3203.
17. Salaun, J.; Ollivier, J. NJC 1981, 5, 587.
18. Holmes, A. B.; Raphael, R. A.; Wellard, N. K. TL 1976, 1539.
19. Miller, J. A.; Zweifel, G. JACS 1983, 105, 1383.

Miles S. Congreve

Cambridge University, UK



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