Synthesis of ¹⁴C‐labeled benzofurano[2,3‐b] benzopyran‐6‐one and its 4‐hydroxycoumarin derivative

Abstract

2‐Isopropyl‐8,9‐dimethoxy‐benzofurano [2,3‐b]furo[2,3‐h] [1] [11‐14C]benzopyran‐6‐one (IVb) and 3‐(2‐hydroxy‐4,5‐dimethoxyphenyl)‐4‐hydroxy‐5′‐isopropylfurano[2′,3′:7,8] [2‐14C]coumarin(Vb) were prepared from isorotenone (Ib) for use in metabolic and other studies. Deoxybenzoin derivative (IIb), obtained from isorotenone, was reacted with ethyl [14C] formate in the presence of sodium to give the corresponding [2‐14C]‐2′‐hydroxyisoflavone (IIIb), which was transformed into the 14C‐labeled benzofurano [2,3‐b]furo[2,3‐h]benzopyran‐6‐one compound (IVb) by the subsequent oxidative cyclization with selenium dioxide. Hydrolysis of compound IVb in alkaline media gave 14C‐labeled 4‐hydroxycoumarin (Vb).