Display options
Cite
Marzabadi CH, Anderson JE, Gonzalez-Outeirino J, et al. Why are silyl ethers conformationally different from alkyl ethers? Chair-chair conformational equilibria in silyloxycyclohexanes and their dependence on the substituents on silicon. The wider roles of eclipsing, of 1,3-repulsive steric interactions, and of attractive steric interactions. J Am Chem Soc. 2003;125(49):15163-73doi: 10.1021/ja035936x.
Marzabadi, C. H., Anderson, J. E., Gonzalez-Outeirino, J., Gaffney, P. R., White, C. G., Tocher, D. A., & Todaro, L. J. (2003). Why are silyl ethers conformationally different from alkyl ethers? Chair-chair conformational equilibria in silyloxycyclohexanes and their dependence on the substituents on silicon. The wider roles of eclipsing, of 1,3-repulsive steric interactions, and of attractive steric interactions. Journal of the American Chemical Society, 125(49), 15163-73. https://doi.org/10.1021/ja035936x
Marzabadi, Cecilia H, et al. "Why are silyl ethers conformationally different from alkyl ethers? Chair-chair conformational equilibria in silyloxycyclohexanes and their dependence on the substituents on silicon. The wider roles of eclipsing, of 1,3-repulsive steric interactions, and of attractive steric interactions." Journal of the American Chemical Society vol. 125,49 (2003): 15163-73. doi: https://doi.org/10.1021/ja035936x
Marzabadi CH, Anderson JE, Gonzalez-Outeirino J, Gaffney PR, White CG, Tocher DA, Todaro LJ. Why are silyl ethers conformationally different from alkyl ethers? Chair-chair conformational equilibria in silyloxycyclohexanes and their dependence on the substituents on silicon. The wider roles of eclipsing, of 1,3-repulsive steric interactions, and of attractive steric interactions. J Am Chem Soc. 2003 Dec 10;125(49):15163-73. doi: 10.1021/ja035936x. PMID: 14653751.
Copy Download .nbib Format: NLM
Share it on

J Am Chem Soc. 2003 Dec 10;125(49):15163-73. doi: 10.1021/ja035936x.

Why are silyl ethers conformationally different from alkyl ethers? Chair-chair conformational equilibria in silyloxycyclohexanes and their dependence on the substituents on silicon. The wider roles of eclipsing, of 1,3-repulsive steric interactions, and of attractive steric interactions.

Journal of the American Chemical Society

Cecilia H Marzabadi, J Edgar Anderson, Jorge Gonzalez-Outeirino, Piers R J Gaffney, Christopher G H White, Derek A Tocher, Louis J Todaro

Affiliations

  1. Department of Chemistry and Biochemistry, Seton Hall University, 400 South Orange Avenue, South Orange, New Jersey 07079, USA. [email protected]

PMID: 14653751 DOI: 10.1021/ja035936x

Abstract

An NMR study of the diaxial/diequatorial chair equilibrium in a range of silylated derivatives of trans-1,4- and trans-1,2-dihydroxycyclohexane is reported and discussed with a view to explaining unusually large populations of chair conformations with axial substituents, noted previously for some monosilyloxycyclohexanes and in some silylated sugars. X-ray diffraction studies of three bis-triphenylsilyloxycyclohexanes are reported and show both axial and equatorial silyloxy groups with the exocyclic bonds eclipsed. Eclipsing is also suggested by molecular mechanics (MM3) calculations on such derivatives. Both axial and equatorial tertiary silyl groups have 1,3-repulsive interactions with whatever substituents or hydrogen atoms are at the two adjacent equatorial positions, and these are relieved by rotation toward the eclipsed conformation of the exocyclic C-O bond. The three substituents on silicon interact attractively with the nine atoms at the 3, 4, and 5-positions of the cyclohexane ring and calculations suggest that these stabilizing interactions are significantly greater in the axial than in the equatorial conformation. An equatorial C-OSiR(3) bond with one or two equatorial neighbors has a restricted potential energy well that becomes much broader when the bond is axial without any equatorial neighbors in the alternative chair. Adjacent silyl groups in the 1,2-disubstituted series interact in a stabilizing way overall in all conformations, this being particularly marked in the diaxial conformation of the more complex ethers. These factors lead to unusually large axial populations.

Publication Types