Effets de substituants en résonance magnétique nucléaire du ¹³C. Etude des dérivés du phényl-2 furanne et du phényl-2 pyrrole

The 13C nmr spectra of derivatives of phenylfuran and phenylpyrrole were studied. The α and β carbons of the heterocycle, conjugated to the substituent X in the para position of the benzene ring, show variations in chemical shifts which bear a simple relationship to the donor properties of X. This is interpreted by the change in electron density caused by this conjugation. This conjugation seems more important in the series of 2-phenylpyrroles than in the series of 2-phenyl-furans especially if the behaviour of then α position is considered.[Journal translation]