Dipole-Stabilized Carbanions: Evidence for a Complex in the α-Lithiation of N,N-Dimethyl-2,4,6-triisopropylbenzamide

Journal of the American Chemical Society

Volumn 105, Issue 7, 1983, Pages 2080-2082

  Al Aseer, Munther ^a   Beak, Peter ^a   Hay, David ^a   Kempf, Dale J ^a   Mills, Sander ^a   Smith, Stanley G ^a  

^a UNIVERSITY OF ILLINOIS AT URBANA CHAMPAIGN   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0001294779     PISSN: 00027863     EISSN: 15205126     Source Type: Journal    
DOI: 10.1021/ja00345a077     Document Type: Article

References (15)

1. Suggestions of lithium complexes in metalations generally are reasonable interpretations based on established donor-acceptor interactions, (a) For cases involving ortho lithiations see: Jastrzebski, J.T.B.H.; van Koten, G.; Konijn, M.; Stam, C.H.J. Am. Chem. Soc. 1982, 104, 5490. Ellison, R.A.; Kotsonis, F.N. Tetrahedron 1973, 29, 805. Finnegan, R.A.; Altschemd, J.W.J. Organomet. Chem. 1967, 9, 193. For an excellent review see: Gschwend, H.W.; Rodriguez, H.R. Org. React. 1979, 26, 1. (b) For cases involving formally dipole-stabilized carbanions See: Beak, P.; Reitz, D.B. Chem. Rev. 1978, 78, 275.
2. Rondan, N.G.; Houk, K.N.; Beak, P.; Zajdel, W.J.; Chandrasekhar, J.; Schleyer, P.V.R. J. Org. Chem. 1981, 46, 4316.
3. Lithiation of primarily the syn-methyl group has been established for 3 under similar reaction conditions: Schlecker, R.; Seebach, D.; Lubosh, W. Helv. Chim. Acta 1978, 61, 3100.
4. The syn- and anti-methyl groups of 3 are nonequivalent on the laboratory time scale. For a related case See: Staab, H.A.; Lauer, D. Chem. Ber. 1968, 101, 864.
5. For cases of amide and lithium ion association See: Staley, R.H.; Beauchamp, J.L. J. Am. Chem. Soc. 1975, 97, 5920. Lassigne, C.; Baine, P.J. Phys. Chem. 1971, 75, 3188. Lees, A.J.; Straughan, B.P.; Gardiner, D.J.J. Mol. Struct. 1979, 54, 37. Egan, W.; Bull, T.E.; Forsen, S.J. Chem. Soc, Chem. Commun. 1972, 1099. Rao, K.G.; Becker, E.D.; Rao, C.N.R. Chem. Soc, Chem. Commun. 1977, 350. Olsher, U.; Elgavish, G.A.; Jagur-Grodzinski, J.J. Am. Chem. Soc. 1980, 102, 3338. Rao, C.P.; Balaram, P.; Rao, C.N.R.J. Chem. Soc, Faraday Trans. 1, 1980, 76, 1008. Hinton, J.F.; Beeler, A.; Harpool, D.; Briggs, R.W.; Pullman, A. Chem. Phys. Lett. 1977, 47, 411. Del Bene, J.E. Chem. Phys. 1979, 40, 329.
6. -1 appears in less than 10 ms.
7. -1 have been reported in carbonyl absorptions on complexation with lithium ion: Bello, J.; Haas, D.; Bello, H.R. Biochemistry 1966, 5. Chakrabarti, P.; Venkatesan, K.; Rao, C.N.R. Proc. R. Soc. London, Ser. A 1981, 375, 127.
8. Bywater, S.; Worsford, D.J. J. Organomet. Chem. 1967, 10, 1.
9. For example, the addition of methyllithium to a ketone is O.25 order in methyl lithium. Smith, S.G.; Charbonneau, L.F.; Novak, D.P.; Brown, T.L. J. Am. Chem. Soc. 1972, 44, 1059. See: Schlosser, M. “Struktur and Reaktivitát Polarer Organometalle”; Springer Verlag: Berlin, 1973; pp. 129-38, for other cases.
10. While such a result might be explained by some combination of the two pathways, among other possibilities, we prefer not to speculate until more information is available.
11. Reitz, D.B.; Beak, P.; Tse, A. J. Org. Chem. 1981, 46, 4316 and references cited therein.
12. Beak, P.; Brown, R.A. J. Org. Chem. 1982, 47, 34. Beak, P.; Snieckus, V. Acc. Chem. Res. 1982, 15, 306.
13. Kempf, D.J.; Wilson, K.D.; Beak, P. J. Org. Chem. 1982, 47, 1610.
14. Meyers, A.I.; TenHoeve, W. J. Am. Chem. Soc. 1980, 102, 7125. Meyers, A.I.; Rieker, W.F.; Fuentes, L.M. Am. Chem. Soc., following paper in this issue.
15. A recent study of deuterium isotope effects by Miller and Saunders suggests such species are important in enolate formation from ketones. Miller, D.J.; Saunders, W.H., Jr. J. Org. Chem. 1982, 47, 5041.