Evidence for electronic buttressing in 4-substituted NN-dimethyl-2-trifluoromethylanilines: long range19F–1H coupling

Abstract

The 1H n.m.r. spectra of a series of 4-substituted derivatives of NN-dimethyl-2-trifluoromethylaniline have been examined; a long range 19F–1H coupling 6J(F,H) between NCH3 and CF3 was confirmed by 19F n.m.r. A linear relation obtains between 6J(F,H) in these compounds and the appropriate Hammett para-substituent constants in accord with the operation of electronic buttressing; a similar correlation holds between the chemical shift of the N-methyl protons and σp.