X-ray structural and13C NMR spectroscopic investigation of 4,7-diaminocoumarins

An x-ray structural study has been made of 7-diethylaminocoumarin and 4-morpholino-7-diethylaminocoumarin. A study has been made of the¹³C NMR spectra of these compounds and other 4,7-diaminocoumarins, in CDCl₃, and in acidic media. These studies have established that the site of first protonation is the nitrogen atom in position 7, and the site of the second protonation is the lactone oxygen atom. It is concluded that the 4-amino group is effectively conjugated with the carbonyl group in 4,7-diaminocoumarins.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 802–810, April, 1991.