Lithium Divinylcuprate1

(CH2=CH)2CuLi

[22903-99-7]  · C4H6CuLi  · Lithium Divinylcuprate  · (MW 124.59)

(vinylating reagent; undergoes conjugate addition reactions1a,b,d and substitution reactions1a,c,d)

Physical Data: clear yellow (prep. from CuI.PBu32a) or light gray solution (prep. from CuBr.SMe2)2b

Solubility: sol THF, Et2O

Preparative Methods: prepared in situ from CuI salts (Copper(I) Iodide,2b Copper(I) Bromide.SMe2,3,2b Copper(I) Iodide-Tributylphosphine2a) and Vinyllithium under N2 or argon atmosphere (see Lithium Dimethylcuprate).

Handling, Storage, and Precautions: air- and moisture-sensitive. Use in a fume hood.

Introduction.

Lithium divinylcuprate displays the characteristic reactivity patterns of lithium diorganocuprates (see Lithium Di-n-butylcuprate, Lithium Dimethylcuprate, Lithium Diphenylcuprate).

Addition Reactions.

Lithium divinylcuprate reacts with a,b-alkenyl ketones,1 esters (eq 1),4 lactones,5 nitro compounds,6 and aldehydes7 with conjugate transfer of the vinyl ligand (see Vinylcopper). Addition of Chlorotrimethylsilane can accelerate the conjugate addition reaction and promote increased stereoselectivity (eq 2).8

The reagent adds stereoselectively (cis addition) to a,b-alkynoates, affording 2,4-dienoates.9 Dienyl esters exclusively afford 1,6-addition products.10 Tandem conjugate addition-enolate trapping is a powerful synthetic method (eq 3).11 The reagent adds to vinyltriphenylphosphonium bromides to provide phosphoranes which can generally be exploited in subsequent chemistry.12 2-Siloxypyrylium salts undergo 1,4-addition, leading to 4-substituted 4H-pyrans.13 1,1-Diactivated cyclopropanes undergo a homoconjugate addition reaction with (CH2=CH)2CuLi.14

Substitution Reactions.

Lithium divinylcuprate participates in substitution reactions with alkyl halides3c,15 and carboxylates.3b,16 Vinyl triflates derived from b-dicarbonyl compounds afford substitution products that may result from addition-elimination reaction pathways (eq 4).17 gem-Dibromocyclopropanes give mono- and disubstituted products, depending upon the reaction temperature.18 Allylic ammonium salts participate in syn-SN2 pathways with good stereo- and regioselectivity.19

Miscellaneous Reactions.

Alkylation of a tricarbonylcyclohexadienyliron salt with lithium divinylcuprate gives moderate yields.20 Reaction of this reagent with oxiranes (eq 5; iodide from CuI),21 2-alkenyl oxetanes (eq 6),22 activated cyclopropanes,23 and aziridines24 affords ring-opened products. Carbocuprations of cyclopropene derivatives have been reported.25 Arylmercurials couple with this reagent, giving fair to good yields of cross-coupled products.26

Related Reagents.

Lithium Bis(1-ethoxyvinyl)cuprate; Lithium Bis(1-methoxyvinyl)cuprate; Lithium Diallylcuprate; Lithium Diisopropenylcuprate; Lithium Di-(E)-1-propenylcuprate; Lithium Divinylcuprate-Tributylphosphine.


1. (a) Lipshutz, B. H.; Sengupta, S. OR 1992, 41, 135. (b) Posner, G. H. OR 1972, 19, 1. (c) Posner, G. H. OR 1975, 22, 253. (d) Faust, J.; Froböse, R. Gmelin Handbook of Inorganic Chemistry; Springer: Berlin, 1983; Copper, Part 2.
2. (a) Harmon, C. A.; Streitwieser, A., Jr. JOC 1973, 38, 549. (b) House, H. O.; Chu, C.-Y.; Wilkins, J. M.; Umen, M. J. JOC 1975, 40, 1460.
3. Brinkmeyer, R. S.; Macdonald, T. L. CC 1978, 876.
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5. (a) Wurster, J. A.; Wilson, L. J.; Morin, G. T.; Liotta, D. TL 1992, 33, 5689. (b) Iwai, K.; Kosugi, H.; Uda, H.; Kawai, M. BCJ 1977, 50, 242.
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9. (a) Li, T.-t.; Wu, Y. L.; Walsgrove, T. C. T 1984, 40, 4701. (b) Li, T.-t.; Wu, Y. L. JACS 1981, 103, 7007. (c) Keck, G. E.; Nickell, D. G. JACS 1980, 102, 3632.
10. Corey, E. J.; Chen, R. H. K. TL 1973, 1611.
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12. Just, G.; O'Connor, B. TL 1985, 26, 1799.
13. Kume, T.; Iwasaki, H.; Yamamoto, Y.; Akiba, K.-y. TL 1987, 28, 6305.
14. Corey, E. J.; Fuchs, P. L. JACS 1972, 94, 4014.
15. (a) Erickson, S. D.; Still, W. C. TL 1990, 31, 4253. (b) Bajgrowicz, J. A.; El Hallaoui, A.; Jacquier, R.; Pigiere, C.; Viallefont, P. TL 1984, 25, 2759. (c) Bajgrowicz, J. A.; El Hallaoui, A.; Jacquier, R.; Pigiere, C.; Viallefont, P. TL 1984, 25, 2231. (d) Lipshutz, B. H.; Wilhelm, R. S. JACS 1981, 103, 7672. (e) Mathias, R.; Weyerstahl, P. CB 1979, 112, 3041.
16. Trost, B. M.; Tanigawa, Y. JACS 1979, 101, 4413.
17. Kant, J.; Sapino, C., Jr.; Baker, S. R. TL 1990, 31, 3389.
18. Kitatani, K.; Hiyama, T.; Nozaki, H. BCJ 1977, 50, 1600.
19. Hutchinson, D. K.; Fuchs, P. L. JACS 1985, 107, 6137.
20. Pearson, A. J. AJC 1977, 30, 345.
21. (a) Lipshutz, B. H.; Ellsworth, E. L.; Siahaan, T. J. JACS 1989, 111, 1351. (b) Corey, E. J.; Nicolaou, K. C.; Beames, D. J. TL 1974, 2439.
22. Larock, R. C.; Stolz-Dunn, S. K. SL 1990, 341.
23. Taber, D. F.; Amedio, J. C., Jr.; Raman, K. JOC 1988, 53, 2984.
24. Dureault, A.; Tranchepain, I.; Greck, C.; Depezay, J.-C. TL 1987, 28, 3341.
25. Nakamura, E.; Isaka, M.; Matsuzawa, S. JACS 1988, 110, 1297.
26. Larock, R. C.; Leach, D. R. OM 1982, 1, 74.

Shou-Yuan Lin & R. Karl Dieter

Clemson University, SC, USA



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