Formation of α-dialkylamino alkyllithium intermediates in the reaction of N,N-dialkylamides with PhMe₂SiLi followed by a second lithium reagent, and their alkylation, fragmentation, cyclisation and rearrangement by proton transfer

Abstract

Tertiary amides (RCONMe₂) react with PhMe₂SiLi, followed by a second lithium reagent NuLi, to give α-dialkylamino alkyllithium intermediates R(Me₂N)CLiNu that undergo protonation 2 → 3, alkylation 2a → 3ab, β-elimination 5 → 6, intramolecular attack on an isolated double bond 9 → 10, intramolecular proton transfer 12, 17 and 22 (arrows), and fragmentation 28 and 34 (arrows), depending upon the structures of the various components R and Nu.

References

1. I. Fleming, S. R. Mack and B. P. Clark, Chem. Commun., 1998, 713.
2. I. Coldham and R. Hufton, Tetrahedron Lett., 1995, 36, 2157 and references cited therein.
3. K. Tamao, T. Yamauchi and Y. Ito, Chem. Lett., 1987, 171; I. Fleming, Pure Appl. Chem., 1990, 62, 1879; P. F. Hudrlik, Y. M. Abdallah and A. M. Hudrlik, Tetrahedron Lett., 1992, 33, 6747; M. Murakami, M. Suginome, K. Fujimoto, H. Nakamura, P. G. Anderson and Y. Ito, J. Am. Chem. Soc., 1993, 115, 6487; S. C. Archibald and I. Fleming, Tetrahedron Lett., 1993, 34, 2387; A. Barbero, D. C. Blakemore, I. Fleming and R. N. Wesley, J. Chem. Soc., Perkin Trans. 1, 1997, 1329.
4. H. Gilman, R. A. Benkeser and G. E. Dunn, J. Am. Chem. Soc., 1950, 72, 1689; S. M. Sieburth and L. Fensterbank, J. Org. Chem., 1993, 58, 6314; J. G. Duboudin, B. Jousseaume and M. Pinet-Vallier, J. Organomet. Chem., 1979, 172, 1.
5. S. Bank, A. Schriesheim and C. A. Rowe, J. Am. Chem. Soc., 1965, 87, 3244; D. A. Hutchinson, K. R. Beck, R. A. Benkeser and J. B. Grutzner, J. Am. Chem. Soc., 1972, 95, 7075; R. A. Benkeser, Synthesis, 1971, 347; M. Schlosser, J. Hartmann and V. David, Helv. Chim. Acta, 1974, 57, 1567.