Lithium Phenylthio(trimethylstannyl)cuprate


[69608-62-4]  · C9H14CuLiSSn  · Lithium Phenylthio(trimethylstannyl)cuprate  · (MW 343.50)

(trimethyltin transfer to the b-carbon of a,b-unsaturated carbonyl compounds1-5 and a,b-alkynic carboxylic acid derivatives6-12)

Physical Data: prepared in situ; the THF solution is dark red.

Solubility: sol THF.

Preparative Methods: lithium (phenylthio)(trimethylstannyl)cuprate (2) is prepared by the addition of solid Phenylthiocopper(I)14 to a THF solution of Trimethylstannyllithium (1)15 (eq 1).

Handling, Storage, and Precautions: should be prepared in dry solvent and used under an inert atmosphere. Since organotin compounds are toxic,13 reaction workup should be carried out in a fume hood.

Reaction With a,b-Unsaturated Carbonyl Systems.

Reagent (2) readily effects conjugate addition of the Me3Sn moiety to a variety of a,b-unsaturated carbonyl compounds, including enones,1,2 b-iodo enones,1,2 and b-trifluoromethanesulfonyl enoates3 (eqs 2-4). Notably, the intermediate enolate anion derived from the reaction of (2) with (R)-(-)-5-methyl-2-cyclohexen-1-one can be trapped with Iodomethane to give, stereoselectively, the ketone (3) (eq 5).4,16 It is pertinent to mention that the conjugate additions of reagents (1) and (2) to bicyclic enones are stereochemically complementary. For example, reaction of (4) with (1) affords the trans-fused substance (5), while reagent (2) converts (4) into the cis-isomer (6).5,17

Reaction With a,b-Alkynic Carboxylic Acid Derivatives.

The stereochemical outcome of the regioselective addition of the elements of Me3Sn-H across the triple bond of a,b-alkynic esters by reagent (2) can be controlled simply by varying the reaction conditions. Thus, reaction at -78 °C in the presence of a proton source provides alkyl (E)-3-trimethylstannyl-2-alkenoates (eq 6),6-8 while use of the reaction conditions outlined in eq 7 produces the corresponding (Z)-isomers.6-8,10-12,18 Similar stereochemical control can be accomplished with a,b-alkynic N,N-dimethylamides as substrates.9 Alkyl (E)- and (Z)-3-trimethylstannyl-2-alkenoates have been shown to be useful synthetic intermediates in a range of contexts, including natural product syntheses.6,8,10,12,16b,19

Related Reagents.

A number of lower order heterocuprates related in composition to (2) have been reported. These include Me3SnCu(Y)Li (Y = C&tbond;CCMe2OMe2,7,20 and CN2,18) and Bu3SnCu(Y)Li (Y = SPh2,21 and CN22-24). To date, these reagents have been employed primarily in reactions similar to some of those described above for (2). A recent report describing the use of Bu3SnCu(CN)Li for the preparation of (Z)-1-tributylstannyl-1-alken-3-ynes (eq 8)24 is noteworthy.

See also 2,3-Bis(trimethylstannyl)-1,3-butadiene; 4-Chloro-2-trimethylstannyl-1-butene; (E)-1-Lithio-2-tributylstannylethylene; Methyl Tributylstannyl Sulfide; trans-1,2-Bis(tributylstannyl)ethylene; Tri-n-butylstannylacetylene; Tri-n-butylstannylcopper; Tri-n-butylstannyllithium; Trimethylstannylcopper-Dimethyl Sulfide; 2-Trimethylstannylmethyl-1,3-butadiene; Trimethylstannyllithium; and (Triphenylstannylmethyl)lithium.

1. Piers, E.; Morton, H. E. CC 1978, 1033.
2. Piers, E.; Morton, H. E.; Chong, J. M. CJC 1987, 65, 78.
3. Piers, E.; Tse, H. L. A. TL 1984, 25, 3155; CJC 1993, 71, 983.
4. Piers, E.; Roberge, J. Y. TL 1991, 32, 5219.
5. Fujiwara, J.; Yamamoto, T.; Sato, T. CL 1992, 1775.
6. Piers, E.; Morton, H. E. JOC 1980, 45, 4263.
7. Piers, E.; Chong, J. M.; Morton, H. E. TL 1981, 22, 4905; T 1989, 45, 363.
8. Piers, E.; Gavai, A. V. CC 1985, 1241; JOC 1990, 55, 2374.
9. Piers, E.; Chong, J. M.; Keay, B. A. TL 1985, 26, 6265.
10. Piers, E.; Friesen, R. W. JOC 1986, 51, 3405; CJC 1992, 70, 1204.
11. Piers, E.; Wai, J. S. M. CC 1987, 1342; CJC 1994, 72, 146.
12. Piers, E.; Friesen, R. W.; Rettig, S. J. CJC 1992, 70, 1385.
13. Pereyre, M.; Quintard, J.-P.; Rahm, A. Tin in Organic Synthesis; Butterworth: London, 1987; pp 6-7.
14. Posner, G. H.; Brunelle, D. J.; Sinoway, L. S 1974, 662.
15. Still, W. C. JACS 1977, 99, 4836.
16. The enantiomerically homogeneous substance (3) has been employed as an intermediate for the synthesis of trans-clerodane diterpenoids: (a) Ref. 4. (b) Piers, E.; Roberge, J. Y. TL 1992, 33, 6923.
17. See also Plamondon, L.; Wuest, J. D. JOC 1991, 56, 2066.
18. Similar chemistry can be achieved by use of the lower order cuprate Me3SnCu(CN)Li: Piers, E.; Wong, T.; Ellis, K. A. CJC 1992, 70, 2058.
19. (a) Piers, E.; Friesen, R. W. CJC 1987, 65, 1681. (b) Piers, E.; Lu, Y.-F. JOC 1988, 53, 926. (c) Piers, E.; Llinas-Brunet, M. JOC 1989, 54, 1483. (d) Piers, E.; Gavai, A. V. JOC 1990, 55, 2380. (e) Piers, E.; Ellis, K. A. TL 1993, 34, 1875. (f) Piers, E.; Wong, T. JOC 1993, 58, 3609.
20. Piers, E.; Chong, J. M. JOC 1982, 47, 1602.
21. (a) Piers, E.; Chong, J. M.; Gustafson, K.; Andersen, R. J. CJC 1984, 62, 1. (b) Harris, F. L.; Weiler, L. TL 1987, 28, 2941. (c) Munt, S. P.; Thomas, E. J. CC 1989, 480. (d) Lowinger, T. B.; Weiler, L. CJC 1990, 68, 1636. (e) Barrett, A. G. M.; Edmunds, J. J.; Hendrix, J. A.; Horita, K.; Parkinson, C. J. CC 1992, 1238.
22. (a) Marino, J. P.; Long, J. K. JACS 1988, 110, 7916. (b) Marino, J. P.; Emonds, M. V. M.; Stengel, P. J.; Oliveira, A. R. M.; Simonelli, F.; Ferreira, J. T. B. TL 1992, 33, 49.
23. Yoneda, R.; Osaki, T.; Harusawa, S.; Kurihara, T. JCS(P1) 1990, 607.
24. Magriotis, P. A.; Scott, M. E.; Kim, K. D. TL 1991, 32, 6085.

Edward Piers & Christine Rogers

University of British Columbia, Vancouver, BC, Canada

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