/sup 17/O NMR spectra of some. cap alpha. -substituted furans, hydrofurnas, and. cap alpha. ,. cap alpha. '-disubstituted furans

This paper studies the transmission of substituent effects via the furan ring, carried out by the C 13 NMR method for 2-substituted furans and nitrofurans, in order to obtain information about the factors influencing the chemical shift of oxygen-17 in these compounds. The transmission of the effect of a substituent to the chemical shift of the oxygen of a C=O group were sensitive to conjugation of the aromatic rings with the carbonyl group, the value of which increase in the series phenyl less than 2-thienyl less than 2-furyl.