Synthesis of thio- and oxo-analogues of isopsoralen

A range of novel 5′-substituted 7-oxo and 7-thioisopsoralens were synthesized via a Claisen rearranged allyl aryl ether followed by reductive ozonolysis in the presence of a suitable solvent. In some cases dimethylthiocarbamoyl chloride was used as a protecting group and to introduce the thiol moiety.