Conformational analysis. A nuclear magnetic resonance study of the conformations of ortho-disubstituted benzenes

Abstract

Results pertinent to the determination of the conformation of the side chain R¹R²R³C attached to a benzene ring with or without an ortho-methyl substituent are reported and discussed. Results comprise dynamic n.m.r., carbon-13 chemical shift, and lanthanide-shift reagent data. When R¹ is particularly large, the preferred conformation is concluded to be close to R¹-perpendicular. In two cases two such conformations with either R² or R³syn to the ortho-substituent are observed.