| abstract |
Novel pyrrolocoumarin derivatives represented by general formula (I), wherein .... represents a single or double bond, R<4> and R<8> each are hydrogen or C1-4alkyl, R<6> is hydrogen or hydroxyl, and R<5> and R<9> each are hydrogen, hydroxyl, C1-4alkyl or C1-4alkoxy, with the proviso that R<6> can only be hydroxyl when .... is a single bond and that R<5> and R<9> are different from hydroxyl when R<6> is hydroxyl, are useful as active ingredients in pharmaceuticals, as colorants and as intermediates. A preferred class of formula (Ia), wherein R<4> and R<8> each are hydrogen or C1-4alkyl, and R<5> and R<9> each are hydrogen, hydroxyl, C1-4alkyl or C1-4alkoxy, may be used in pharmaceutical compositions for the photochemotherapy of psoriasis. The compounds of formula (I) can be prepared by a cyclisation reaction according to Pechmann, preferably followed by a dehydrogenation or dehydration reaction to form compounds of formula (Ia). |