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

Abstract

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.

Applications of phenyliodine(III) diacetate in heterocyclic ringformations: An updatefrom 2015 to date

“…Due to the significance of the spiroheterocycles, a significant class of compounds, the construction of this unique kind of heterocyclic skeleton has received a great deal of attention. The new 3 H ,3 ′H ‐spiro[benzofuran‐2,2′‐benzo[b]thiophene] was made by Du and co‐workers [73] using the PIDA/CuBr method (Scheme 70). The interaction of the compound 3,3′‐dione with ( Z )‐3‐hydroxy‐1‐(2‐hydroxyphenyl)‐3‐(2‐halogenphenyl)prop‐2‐en‐1‐ones in the presence of potassium ethylxanthate.…”