Intracluster transmetalation of cuprates with stannanes

Abstract

Alkylarylcuprates with intramolecularly tethered stannanes undergo an intracluster Cu^I/Sn^IV transmetalation to yield arylstannanes.

References

1. J. R. Behling, K. A. Babiak, J. S. Ng, A. L. Campbell, R. Moretti, M. Koerner and B. H. Lipshutz, J. Am. Chem. Soc., 1988, 110, 2641 This method has been successfully extended for the preparation of allyl cuprates.
2. B. H. Lipshutz, R. Crow, S. H. Dimock, E. L. Ellsworth, R. A. J. Smith and J. R. Behling, J. Am. Chem. Soc., 1990, 112, 4063.
3. M. Benecie and K. Khuong-Huu, Synlett, 1992, 266.
4. D. J. Cárdenas, C. Mateo and A. M. Echavarren, Angew. Chem., Int. Ed. Engl., 1994, 33, 2445; C. Mateo, D. J. Cárdenas, C. Fernández-Rivas and A. M. Echavarren, Chem. Eur. J., 1996, 2, 1596; C. Mateo, C. Fernández-Rivas, A. M. Echavarren and D. J. Cárdenas, Organometallics, 1997, 16, 1997; C. Mateo, C. Fernández-Rivas, D. J. Cárdenas and A. M. Echavarren, Organometallics, 1998, 17, 3661.
5. Y. Kondo, T. Matsudaira, J. Sato, N. Murata and T. Sakamoto, Angew. Chem., Int. Ed. Engl., 1996, 35, 736.
6. For the structure of organocuprates generated from CuCN: N. Krause, Angew. Chem., Int. Ed., 1999, 38, 79.
7. Formation of an arylcuprate intermediate was demonstrated by the formation of o-allylphenol by treatment o-iodophenol allyl ether with 1a(73% yield). For a similar rearrangement: J. Barluenga, R. Sanz and F. J. Fañanás, Tetrahedron Lett., 1997, 38, 6103.
8. Best results were obtained with 1.1–1.5 equiv. of cuprate 1a. The use of larger amounts led to lower yields of 4a, presumably as a result of the early quenching of MeI by the excess 1a(ref. 5).
9. The mixed cuprates could not be prepared by the direct Sn/Cu exchange from the o-substituted arylstannanes, probably due to steric hindrance. Thus, no reaction was observed in the reaction of 1a or 1b with 2-(tri-n-butylstannylmethoxy)phenyltri-n-butylstannane, while the reaction between phenyltri-n-butylstannane and 1b yields tetra-n-butylstanne (74% isolated yield).
10. P. Beak, Acc. Chem. Res., 1992, 25, 215; M. L. Kurtzweil, D. Loo and P. Beak, J. Am. Chem. Soc., 1993, 115, 421.
11. The only new stannane was methyltributylstannane, resulting from the selective transmetalation of 5 with [LiCuMePh·LiCN]. A similar reaction with [LiCuBu₂·LiCN] afforded Bu₄Sn.
12. Determined by ¹H NMR and GC-EI-MS analysis.
13. G. van Koten, S. L. James and J. T. B. H. Jastrzebski, Comprehensive Organometallic Chemistry II, Pergamon, Oxford, 1995, vol. 3, ch. 2.
14. Coordination of the ethers to the lithium atoms is omitted for clarity in Scheme 2. The arrows in 10 only indicate the group connectivity in the rearranged product 11.
15. Variable amounts of 12 and phenol, the product of protodestannylation of 12, were obtained when oxygen was present before the aqueous workup.