Synthesis of Spiro[benzofuran‐2,2'‐benzo[b]thiophene]‐3,3'‐diones via PIDA/CuBr‐Mediated Spirocyclization

A phenyliodine(III) diacetate (PIDA)/CuBr‐mediated construction of the novel 3H,3'H‐spiro[benzofuran‐2,2'‐benzo[b]thiophene]‐3,3'‐dione skeleton was realized from the reaction of (Z)‐3‐hydroxy‐1‐(2‐hydroxyphenyl)‐3‐(2‐halogenphenyl)prop‐2‐en‐1‐ones with potassium ethylxanthate in the presence of 1,10‐phen. The reaction sequence was postulated to encompass a PIDA‐mediated oxidative C–O bond formation followed by a CuBr‐mediated spirocyclization step. A phenyliodine(III) diacetate (PIDA)/CuBr‐mediated construction of the novel 3H,3'H‐spiro[benzofuran‐2,2'‐benzo[b]thiophene]‐3,3'‐dione skeleton was realized from the reaction of (Z)‐3‐hydroxy‐1‐(2‐hydroxyphenyl)‐3‐(2‐halogenphenyl)prop‐2‐en‐1‐ones with potassium ethylxanthate in the presence of 1,10‐phen. The reaction sequence was postulated to encompass a PIDA‐mediated oxidative C–O bond formation followed by a CuBr‐mediated spirocyclization step.