Lithium Diphenylcuprate1


[23402-69-9]  · C12H10CuLi  · Lithium Diphenylcuprate  · (MW 224.71)

(phenylating reagent; undergoes conjugate addition reactions,1a,b,d substitution reactions with alkyl, vinyl, and allylic substrates,1a,c,d oxidative coupling,2 and addition to benzynes3)

Physical Data: Ph2CuLi.0.4Et2O isolated as white crystals or yellow powder when dry; [Ph2CuLi.3.25LiBr.4.2C4H8O2] precipitated from dioxane;4a X-ray structure of [Ph2CuLi.Et2O] prepared from CuI.PBu3;4b 13C NMR (DMS) of Ph2CuLi prepared from CuBr: d 163.1, 143.6, 128.1, 127.0 ppm; 6Li NMR d -0.57 ppm.4c

Solubility: sol THF, Et2O, benzene, hexane.

Preparative Methods: prepared in situ from CuI salts (Copper(I) Iodide, Copper(I) Bromide, CuBr.SMe2 or Copper(I) Iodide-Tributylphosphine) under N2 or argon atmosphere (see Lithium Dimethylcuprate).1a Polymer-supported Ph2CuLi can be prepared.5

Handling, Storage, and Precautions: dry crystals are stable at 25 °C, but the reagent decomposes in solution. Air and moisture sensitive. Use in a fume hood.

Addition Reactions.

Ph2CuLi reacts with a,b-alkenyl ketones, aldehydes,6 esters,7 lactones,8 malonates,9 sulfones, and N-tosyl-1-azoalkenes10 with conjugate transfer of the phenyl ligand.1 a,b-Ynones,11a ynoates,11b and ynoic acids11b also participate in 1,4-additions with Ph2CuLi, while yields vary widely1d with nitroalkenes. Appropriate location of nucleofuge substituents, including s-complexed transition metals,12a can result in addition-elimination12b,c or addition-elimination-addition (eq 1)12d reactions. Subsequent exploitation of chemo- (eq 2)7b or regioselectively generated enolate anions represents a powerful dimension of cuprate conjugate addition reactions (eq 37c).13 Acylvinylcyclopropanes undergo 1,6-addition14a and 1,1-diactivated cyclopropanes undergo homoconjugate addition.14b

1,2-Addition of Ph2CuLi to a chiral g-alkoxy-a,b-enal occurs with vinylogous Cram selectivity in the presence of Chlorotrimethylsilane despite the general preference of this reagent to add 1,4 to enals.15 Although carbocupration of acetylene has been achieved with Ph2CuLi, the generality of the reaction has not been established.1d

Substitution Reactions.

Ph2CuLi participates in substitution reactions with alkyl halides,1 sulfinates,16 and sulfonate esters (eq 4).17 Vinyl halides,18 triflates,19a,b and phenyl(vinyl)iodonium salts (eq 5)19c afford good yields of substitution products with retention of configuration, which is in marked contrast to the poor participation of aryl halides.1 Anhydrides,20a thiol esters,20b and acyl halides1d react with Ph2CuLi to afford aryl ketones.

Allylic halides (eq 6),21 oxiranes (eq 7),22 carboxylates, oxazolidines,23 sulfonimides,24 and ammonium salts25 participate in anti-SN2 pathways, although regio- and stereochemistry can vary.1

Miscellaneous Reactions.

Ph2CuLi undergoes oxidative dimerization2a and oxidative coupling2b with amines. Reaction of Ph2CuLi with a,a-dibromo ketones26 leads to a-phenyl ketones via cyclopropanone intermediates; the reagent also adds to benzynes.3

Related Reagents.

Lithium Dimethylcuprate; Lithium Di-p-tolylcuprate.

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. In Gmelin Handbook of Inorganic Chemistry; Springer: Berlin, 1983; Copper, Part 2.
2. (a) Whitesides, G. M.; San Filippo, J., Jr.; Casey, C. P.; Panek, E. J. JACS 1967, 89, 5302. (b) Yamamoto, H.; Maruoka, K. JOC 1980, 45, 2739.
3. Meyers, A. I.; Pansegrau, P. D. CC 1985, 690.
4. (a) Costa, G.; Camus, A.; Gatti, L.; Marsich, N. JOM 1966, 5, 568. (b) Lorenzen, N. P.; Weiss, E. AG(E) 1990, 29, 300. (c) Bertz, S. H.; Dabbagh, G. JACS 1988, 110, 3668.
5. Schwartz, R. H.; San Filippo, J., Jr. JOC 1979, 44, 2705.
6. (a) Nakamura, E.; Matsuzawa, S.; Horiguchi, Y.; Kuwajima, I. TL 1986, 27, 4029. (b) Chuit, C.; Foulon, J. P.; Normant, J. F. T 1981, 37, 1385.
7. (a) Gustafsson, B.; Nilsson, M.; Ullenius, C. ACS 1977, 31B, 667. (b) Fang, C.; Suganuma, K.; Suemune, H.; Sakai, K. JCS(P1) 1991, 1549. (c) Fang, C.; Suemune, H.; Sakai, K. TL 1990, 31, 4751. (d) Fang, C.; Ogawa, T.; Suemune, H.; Sakai, K. TA 1991, 2, 389.
8. Hizuka, M.; Fang, C.; Suemune, H.; Sakai, K. CPB 1989, 37, 1185.
9. Kruger, D.; Sopchik, A. E.; Kingsbury, C. A. JOC 1984, 49, 778.
10. Sacks, C. E.; Fuchs, P. L. JACS 1975, 97, 7372.
11. (a) Degl'Innocenti, A.; Stucchi, E.; Capperucci, A.; Mordini, A.; Reginato, G.; Ricci, A. SL 1992, 329. (b) Klein, J.; Levene, R. JCS(P2) 1973, 1971.
12. (a) LiMing, N.; Belot, J. A.; Welker, M. E. TL 1992, 33, 177. (b) Charonnat, J. A.; Mitchell, A. L.; Keogh, B. P. TL 1990, 31, 315. (c) Tamura, R.; Tamai, S.; Katayama, H.; Suzuki, H. TL 1989, 30, 3685. (d) Smith, A. B., III; Wexler, B. A.; Slade, J. S. TL 1980, 21, 3237.
13. Taylor, R. J. K. S 1985, 364.
14. (a) Miyaura, N.; Itoh, M.; Sasaki, N.; Suzuki, A. S 1975, 317. (b) Daviaud, G.; Miginiac, P. TL 1972, 997.
15. Arai, M.; Nemoto, T.; Ohashi, Y.; Nakamura, E. SL 1992, 309.
16. Harpp, D. N.; Vines, S. M.; Montillier, J. P.; Chan, T. H. JOC 1976, 41, 3987.
17. Kotsuki, H.; Miyazaki, A.; Ochi, M.; Sims, J. J. BCJ 1991, 64, 721.
18. Worm, A. T.; Brewster, J. H. JOC 1970, 35, 1715.
19. (a) McMurry, J. E.; Scott, W. J. TL 1980, 21, 4313. (b) Tsushima, K.; Araki, K.; Murai, A. CL 1989, 1313. (c) Ochiai, M.; Sumi, K.; Takaoka, Y.; Kunishima, M.; Nagao, Y.; Shiro, M.; Fujita, E. T 1988, 44, 4095.
20. (a) Rahman, M. T.; Nahar, S. K. JOM 1992, 425, 201. (b) Anderson, R. J.; Henrick, C. A.; Rosenblum, L. D. JACS 1974, 96, 3654.
21. Mathew, J. JOC 1992, 57, 2753.
22. Wender, P. A.; Erhardt, J. M.; Letendre, L. J. JACS 1981, 103, 2114.
23. Berlan, J.; Besace, Y. T 1986, 42, 4767.
24. Muller, P.; Phuong, N. T. M. TL 1978, 4727.
25. Hutchinson, D. K.; Fuchs, P. L. JACS 1985, 107, 6137.
26. Lei, X.; Doubleday, C., Jr.; Turro, N. J. TL 1986, 27, 4671.

R. Karl Dieter

Clemson University, SC, USA

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