A method for the synthesis of a wide range of fused thiophenes, including those fused with lactams, lactones, or cyclic ethers, was developed from a rhodium-catalyzed intramolecular transannulation reaction of alkynyl thiadiazoles. This transannulation reaction provides an efficient platform for the construction of a variety of 5,n-fused thiophenes from readily available starting materials together with the release of molecular nitrogen.

A synthetic method to prepare a wide range of 2H‐indazoles was developed via a tandem palladium‐catalyzed deacylative cross‐coupling reaction of 2‐iodoazoarenes and 2‐iodoaryltriazenes with acyldiazoacetates and denitrogenative cyclization reaction of in situ generated diazoacetates having azoaryl and triazenylaryl moieties in one‐pot. Additionally, azoaryl‐substituted diazoacetates underwent palladium‐catalyzed denitrogenative cyclization to produce 2H‐indazoles. The present reaction is a good example in which a Pd(0)‐catalyst is involved in two catalytic cycles in one‐pot.magnified image

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