The synthesis of the benzothiopyranoindazoles (3), a new class of chromophore modified anthracenediones related to mitoxantrone (l), is described. In this structural class the quinone moiety, which is believed to be responsible for the cardiotoxicity of the anthracyclines, has been designed out. The synthesis of the benzothiopyranoindazoles was carried out by a multistep sequence from requisite l-chloro-4-nitro-9H-thioxanthen-9-one ...
