Collect. Czech. Chem. Commun. 1979, 44, 3378-3384

The gauche effect on conformation. α-Substituted sulfones and N-substituted sulfonamides

Otto Exnera and Jan B. F. N. Engbertsb

a Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6
b Department of Organic Chemistry, University of Groningen, The Netherlands


The dipole moments of α-halogenosulfones IIa-f in benzene solution revealed the conformation C, those of N-methyl-N-nitrosulfonamides IIIa-c the conformation F. In either case the conformational preference is governed by the gauche rule which may be worded in a modified version that symmetrical positions of polar bonds and/or of lone electron pairs are disfavoured. A lone electron pair appears to be more significant than a polar bond.