[3220-49-3]  · C6H5Cu  · Phenylcopper  · (MW 140.66)

(nucleophilic reagent for substitution reactions;1a,b selective reagent for conjugate additions;1a,c,d,2 couples with aryl halides to form biaryls3)

Alternate Name: copper phenyl.

Physical Data: slightly yellow solid; mp 100 °C (dec).13

Solubility: insol ether, tetrahydrofuran.

Preparative Methods: phenylcopper and other arylcopper species are most commonly prepared from equimolar amounts of alkyllithium or Grignard reagent and purified copper(I) halide in ether or THF.4 Arylcoppers can be prepared from the corresponding aryl halides and highly active zerovalent Copper.5

Handling, Storage, and Precautions: decomposes on heating in solution. Hydrolyzed by H2O.13 Use in a fume hood.

Nucleophilic Substitutions.

Arylcoppers are suitable nucleophiles for reaction with acid chlorides (to prepare aryl ketones),5,6 primary alkyl halides,5a,b epoxides,5c b-lactones (to prepare b-aryl carboxylic acids),7 and 1,3-dioxolan-4-ones (to prepare protected secondary alcohols).8 Arylcopper species favor SN2 substitutions of allylic bromides9 and propargyl sulfonates.4d See also Methylcopper.

Conjugate Additions.

Phenylcopper will add in Michael fashion to conjugated enones,6 cyanoalkynes,10 alkynyl sulfoxides,4c and alkenyl sulfones.11 When performed in the presence of Chlorotrimethylsilane12a,b or Iodotrimethylsilane,12b,c Michael addition of arylcoppers to enones, enals, and enoates is accelerated and 1,4-selectivity (vs. 1,2) is enhanced. Rate and selectivity can also be improved by the presence of Dimethyl Sulfide.6 See also Phenylcopper-Boron Trifluoride Etherate.

Biaryl Synthesis.

Although arylcoppers are not typically used for the synthesis of unsymmetrical biaryls, a combination of phenylcopper and 2-iodopyridine, or 2-pyridylcopper and an iodoarene, provides 2-arylpyridines in good yield.4b

1. (a) Normant, J. F. S 1972, 63. (b) Posner, G. H. OR 1975, 22, 253. (c) Posner, G. H. OR 1972, 19, 1. (d) Taylor, R. J. K. S 1985, 364.
2. House, H. O.; Respess, W. L.; Whitesides, G. M. JOC 1966, 31, 3128.
3. (a) Nilsson, M.; Wennerström, O. TL 1968, 3307. (b) Nilsson, M.; Wennerström, O. ACS 1970, 24, 482. (c) Fanta, P. E. S 1974, 9.
4. (a) Costa, G.; Camus, A.; Gatti, L.; Marsich, N. JOM 1966, 5, 568. (b) Malmberg, H.; Nilsson, M. T 1986, 42, 3981. (c) Truce, W. E.; Lusch, M. J. JOC 1978, 43, 2252. (d) Westmijze, H.; Vermeer, P. S 1979, 390. (e) Ruitenberg, K.; Westmijze, H.; Kleijn, H.; Vermeer, P. JOM 1984, 277, 227.
5. (a) Ebert, G. W.; Rieke, R. D. JOC 1984, 49, 5280. (b) Ebert, G. W.; Rieke, R. D. JOC 1988, 53, 4482. (c) Rieke, R. D.; Wehmeyer, R. M.; Wu, T.-C.; Ebert, G. W. T 1989, 45, 443.
6. Bertz, S. H.; Dabbagh, G. T 1989, 45, 425.
7. Kawashima, M.; Sato, T.; Fujisawa, T. T 1989, 45, 403.
8. Heckmann, B.; Mioskowski, C.; Yu, J.; Falck, J. R. TL 1992, 33, 5201.
9. Kang, J.; Cho, W.; Lee, W. K. JOC 1984, 49, 1838.
10. Westmijze, H.; Kleijn, H.; Vermeer, P. S 1978, 454.
11. Hutchinson, D. K.; Hardinger, S. A.; Fuchs, P. L. TL 1986, 27, 1425.
12. (a) Matsuzawa, S.; Horiguchi, Y.; Nakamura, E.; Kuwajima, I. T 1989, 45, 349. (b) Bergdahl, M.; Lindstedt, E.-L.; Nilsson, M.; Olsson, T. T 1988, 44, 2055. (c) Bergdahl, M.; Lindstedt, E.-L.; Nilsson, M.; Olsson, T. T 1989, 45, 535.
13. Dictionary of Organometallic Compounds, 2nd ed.; Macintyre, J. E., Ed.; Chapman and Hall: New York, 1995; Vol. 1, p 1079.

John N. Haseltine

Georgia Institute of Technology, Atlanta, GA, USA

Copyright 1995-2000 by John Wiley & Sons, Ltd. All rights reserved.