Abstract
Alkynyl difluoro silanes can react with nucleophiles either directly at the silane unit by displacing the fluorine atoms (direct addition) or, in contrast, the nucleophile can attack the β -carbon of the adjacent alkynyl group (conjugate addition). By using this type of conjugate addition a number of fascinating unsaturated silicon and germanium compounds have been prepared in the past using alkyl substituted phenyl groups as substituents. Therefore we wanted to investigate which regioselectivity isobserved in the case of such an alkynyl difluoro silane shielded by a terphenyl substituent (Mes2C6H3-, Mes =2,4,6-trimethylphenyl). Surprisingly, the reaction with phenyl lithium leads exclusively to direct displacement rather than conjugate addition, which we could prove by X-ray crystallography of 5. Moreover, the synthesis, spectroscopic data and crystal structures of important intermediates to the starting alkynyl difluoro terphenyl silane 2 are presented.
Similar content being viewed by others
References
Brook, M.A. 2000 Silicon in Organic, Organometallic, and Polymer Chemistry.New York: Wiley, pp. 115–141.
Jones, P.R., Lim, T.F.O. & Pierce, R.A. 1980 J. Am. Chem. Soc. 102, 4970.
Jones, P.R., Cheng, A.H.-B. & Albanesi, T.E. 1984 Organometallics 3, 78.
Ziche, W., Auner, N. & Behm, J. 1992 Organometallics 11, 2494.
Auner, N., Heikenwä lder, C.-R. & Wagner, C. 1993 Organometallics 12, 4135.
Trommer, M., Miracle, G.E., Eichler, B.E., Powell, D.R. & West, R. 1997 Organometallics 16, 5737.
Mü ller, T., Bendikov, M., Auner, N. & Apeloig, Y. 2001 Organometallics 20, 598.
Miracle, G.E., Ball, J.L., Powell, D.R. & West, R. 1993 J. Am. Chem. Soc. 115, 11598.
Eichler, B.E., Powell, D.R. & West, R. 1998 Organometallics 17, 2147.
Pietschnig, R. & Merz, K. 2001 J. Chem. Soc., Chem. Commun. 1210.
Pietschnig, R., West, R. & Powell, D.R. 2000 Organometallics 19, 2724.
Pu, L., Twamley, B. & Power, P.P. 2000 J. Am. Chem. Soc. 122, 3524.
Bibal, C., Mazieres, S., Gornitzka, H. and Couret, C. 2001 Angew. Chem. Int. Ed. Engl. 40, 952.
Stender, M., Phillips, A.D., Wright, R.J. & Power, P.P. 2002 Angew. Chem. 114, 1863.
Wiberg, N., Niedermayer, W., Fischer, G., Nö th, H. & Suter, M. 2002 Eur. J. Inorg. Chem. 1066.
Eaborn, C. 1952 J. Chem. Soc. 2840.
Uhlig, W. & Tretner, C. 1994 J. Organomet. Chem. 467, 31.
Wannagat, U. & Niederprü m, H. 1961 Chem. Ber. 94, 1540.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Pietschnig, R., Schäfer, S. Direct versus conjugate addition to a terphenyl substituted alkynyl difluoro silane. Silicon Chemistry 2, 131–135 (2003). https://doi.org/10.1023/B:SILC.0000046708.47499.0b
Issue Date:
DOI: https://doi.org/10.1023/B:SILC.0000046708.47499.0b