Download PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... A commonly encountered problem in the synthesis of 3-aminocoumarins is the formation of 3-hydroxycoumarins. A solution to this problem, which involves non-aqueous formation of the 3-aminocoumarin system, is described. ... A commonly encountered problem in the ...