Crotyllithium

[16327-44-9]  · C4H7Li  · Crotyllithium  · (MW 62.03) (E)

[13950-06-6] (Z)

[51760-91-9]

(crotylating agent in substitutions and additions; used to attach crotyl groups to other metals and nonmetals)

Physical Data: (E) and (Z) forms equilibrate rapidly in solution, with typical equilibrium composition 85% (Z)-15% (E) as shown by 1H and 13C NMR.1,2

Solubility: sol ethers; sparingly sol hydrocarbons.

Preparative Methods: by metallating 1-butene or (E)- and/or (Z)-2-butene with n-Butyllithium/N,N,N,N-Tetramethylethylenediamine;1b from organotin1a or organoselenium3 compounds by exchange with Methyllithium or butyllithium.

Form Supplied in: prepared in situ and used directly.

Handling, Storage, and Precautions: must be prepared and transferred under inert gas to exclude oxygen and moisture.

Reactions.

Crotyllithium alkylates mainly at the less hindered end to give mixtures of (E) and (Z) products with the latter predominating due to the greater stability of (Z)-crotyllithium.1b,4 Additions to aldehydes and ketones5 can sometimes be made more stereo- and regioselective by adding boron,6 zirconium,7 or chromium8 compounds. Crotyllithium has been used to make crotylpalladium reagents.9

When stereospecificity is desired, crotylpotassiums are preferable to crotyllithiums since they can be made and reacted at low temperatures with preservation of configuration,10 e.g. to make crotyldiisopinocampheylboranes (eqs 1 and 2; Ipc = isopinocampheyl) for asymmetric syntheses (see B-Crotyldiisopinocampheylborane).11

Related Reagents.

Table 1 lists some useful crotyllithium derivatives. The first five entries all strongly prefer the (Z) geometry.12,13 The last, with no stereochemical complications, provides isoprene units in coupling reactions with alkyl bromides.4 See also Allyllithium and Allylmagnesium Bromide.


1. (a) Seyferth, D.; Jula, T. F. JOM 1974, 66, 195. (b) Bates, R. B.; Beavers, W. A. JACS 1974, 96, 5001.
2. van Dongen, J. P. C. M.; van Dijkman, H. W. D.; de Bie, M. J. A. RTC 1974, 93, 29.
3. Clarembeau, M.; Krief, A. TL 1984, 25, 3629.
4. Korte, W. D.; Cripe, K.; Cooke, R. JOC 1974, 39, 1168.
5. (a) Rautenstrauch, V. HCA 1974, 57, 496. (b) Yamamoto, Y. ACR 1987, 20, 243.
6. Yamamoto, Y.; Yatagai, H.; Maruyama, K. CC 1980, 1072.
7. Yamamoto, Y.; Maruyama, K. TL 1981, 22, 2895.
8. Uemura, M.; Minami, T.; Isobe, K.; Kobayashi, T.; Hayashi, Y. TL 1986, 27, 967.
9. Goliaszewski, A.; Schwartz, J. T 1985, 41, 5779.
10. Schlosser, M.; Hartmann, J.; David, V. HCA 1974, 57, 1567.
11. Brown, H. C.; Bhat, K. S. JACS 1986, 108, 293.
12. Schlosser, M.; Hartmann, J. JACS 1976, 98, 4674.
13. Seyferth, D.; Mammarella, R. E. JOM 1979, 177, 53.
14. Beak, P.; Hunter, J. E.; Jun, Y. M. JACS 1983, 105, 6350.
15. Cazes, B.; Julia, S. TL 1978, 4065.

Robert B. Bates & Sriyani Caldera

University of Arizona, Tucson, AZ, USA



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