Büchner Reactions Catalyzed by a Silver(I) Pyridylpyrrolide: Understanding Arene C═C Insertion Selectivity

The complex Ag3(μ2-3,5-(CF3)2PyrPy)3 (3,5-(CF3)2PyrPy = 2,2′-pyridylpyrrolide(1−) ligand) catalytically promotes the insertion of the carbene of ethyl diazoacetate (EDA), at room temperature, into the C═C bond of a series of arenes to ultimately ring-open them and form the corresponding cycloheptatrienes. In one case, the norcaradiene intermediate can be isolated, while regioselective C═C insertion can be promoted with certain arene substrates. The mechanism of C═C insertion, preference over C–H insertion, and origin of C═C regioselectivity has been probed by a combination of experimental and theoretical studies.