Hydroarylation of 2‐Aryloxybut‐1‐en‐3‐ynes via Pd/Acid‐Catalyzed C−H Bond Activation: A Concise Synthesis of 2,3‐Bismethylene‐2,3‐dihydrobenzofurans

Abstract

An intramolecular exo-hydroarylation of 2-aryloxy-1,4-disilylbut-1-en-3-ynes via ortho-C-H bond activation under palladium(0) and acid catalysis was found to give 2,3-bis(silylmethylidene)-2,3-dihydrobenzofurans. The two silyl groups present probably promoted the reaction and played a key role in stabilizing the diene moiety in the product. The products readily led to functionalized condensed cycles by a Diels-Alder reaction.

Collaborative Interaction of Carbon–Carbon Unsaturated Bond Groups with Transition-metal Catalysts for C–H Bond Functionalization

“…24 The mechanistic concept of the collaboration of Pd(0) and acid catalysts with alkynyl groups is applied to exo- hydroarylation of CC triple bond in enyne substrates, 2-aryloxy-1,4-disilylbut-1-en-3-ynes, via ortho-CH bond activation (Scheme 18). 25 The products, 2,3-bismethylene-2,3-dihydrobenzofurans, undergo [4+2]-cycloaddition with dienophiles to form condensed cyclic compounds. That is, this reaction system allows to construct condensed cycles from the enynes with 100% atom economy.…”