Syntheses and properties of two heterocyclically substituted hypericin derivatives: 10,11-dibenzothiazolyl-10,11-didemethylhypericin and 10,11-dibenzoxazolyl-10,11-didemethylhypericin

The syntheses of the two heterocyclically substituted title hypericin derivatives were achieved starting either from 6-benzothiazolyt-tri-O-methyl-6-demethylemodin or 6-benzoxazolyl-tri-O-methyl-6-demethylemodin. The use of microwave assisted synthesis for the preparation of these anthraquinone synthons and the chemical as well as photochemical properties of the corresponding unique hypericin derivatives, which might constitute new photodynamic therapy agents, are reported. The tautomeric and stereochemical aspects of these hypericin derivatives were investigated by means of semiempirical calculations (AM1).