Synthesis of 4,7,9‐trimethyl‐2 H ‐thieno[3,2‐ g ]‐1‐benzopyran‐2‐one. A psoralen isostere

The title compound, an isostere of 4,5′,8‐trimethylpsoralen, was prepared in good yield from 7‐[(2‐bromo‐allyl)thio]‐4,8‐dimethylcoumarin via a thio‐Claisen rearrangement. The structure of the final product was determined by proton nmr decoupling experiments.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96405/1/5570170513_ftp.pd