Synthesis of [7-(14) C]bergapten.

Bergapten (1) is a furocoumarin natural product and currently employed to treat skin disorders. Since past attempts to radiolabel 1 with (14) C were limited to only its 5-methoxy group, a synthesis of the required ring [7-(14) C]1 is now described. The literature reported precursor 4-methoxy-6-hydroxybenzofuran-5-carboxaldehyde (3) was Wittig reacted with stabilized [carbonyl-(14) C]methoxycarbonylmethylenetriphenylphosphorane (4) to obtain [7-(14) C]1 in 47% radiochemical yield, with the desired product being characterized by thin-layer chromatography, HPLC, m.p. and proton NMR.