Substituent efects on the carbon-13 chemical shifts in α-phenylpyridylacrylic acids

Abstract

The 13C N.M.R. spectra of some substituted α-phenylpyridylacrylic acids, α-phenyl, α-(3-pyrydyl) and α-(3-pyrydyl-N-oxide) cinnamic acids were determined in deuterated dimethyl sulfoxide (d6-DMSO). It has been shown that the subsitutent chemical shifts (SCS) for Cβatom ethylenic bond of the examined compounds correlated linearely with the summ of the corresponding substituent constants in the both rings (σx + σY). This correlation was interpreted as evidence that the electronic effects of both substituents are involved in conjugated aromatic system. © 1992.