Heck-type coupling of intramolecularly-generated thiopalladacycles with alkenes: One pot syntheses of 3-alkenylbenzo[b]thiophenes

A method for stoichiometric functionalization of benzothiophene is developed by Heck-type coupling of alkenes with intramolecularly-generated thiopalladacycles obtained from palladium salts and ortho-thioanisole-substituted propargyl imines. The synthetic strategy for preparing structurally diverse 3-alkenylbenzo[b]thiophene is also extended to 3-alkenylbenzo[b]selenophenes.

Graphical AbstractA method for stoichiometric functionalization of benzothiophene is developed by Heck-type-coupling of alkenes with intramolecularly-generated thiopalladacycle obtained from palladium salts and ortho-thioanisole substituted propargyl imines. The synthetic strategy of structurally diverse 3-alkenylbenzo[b]thiophene is also extended to 3-alkenylbenzo[b]selenophenes.Figure optionsDownload as PowerPoint slideHighlights
► Intramolecularly-generated an organopalladium intermediate is isolated.
► The stability and reactivity of the thiopalladacycle is demonstrated.
► Structurally diversed 3-alkenylbenzo[b]thiophenes are synthesized.
► The method is also extended to 2,3-disubstituted benzo[b]selenophenes.