was compared with that of unsubstituted naphthoyloxyl radicals. The introduction of a methoxy group in the naphthalene ring stabilizes the naphthoyloxyl radicals to prevent their decarboxylation completely and reduces remarkably their reactivities in the addition to olefins and hydrogen-atom abstraction. The structure of the naphthoyloxyl radicals was discussed on the basis of their absorption spectra
The present invention relates to novel naphthalene derivatives of formula (I), wherein R
1
, R
2
, R
3
and X are as defined in the description, and preparation thereof. The compounds of formula (I) are useful as pharmaceuticals.
A series of 1- and 2-naphthoyloxyl radicals are generated from photocleavage of 1-(naphthoyloxy)-2-pyridones in acetonitrile. Introduction of a methoxy group in the naphthalene ring stabilized the naphthoyloxyl radicals to prevent decarboxylation completely and reduced remarkably their reactivities of addition to olefins and hydrogen-atom abstraction.