Metal‐Free Temperature‐Controlled Regiodivergent Borylative Cyclizations of Enynes: BCl<sub>3</sub>‐Promoted Skeletal Rearrangement
Ana Milián, Manuel A. Fernández‐Rodríguez, Estı́baliz Merino, Juan J. Vaquero, Patricia García‐García
Abstract
Abstract Metal‐free borylative cyclization of biphenyl‐embedded 1,3,5‐trien‐7‐ynes in the presence of simple and inexpensive BCl 3 provided synthetically useful borylated building blocks. The outcome of the process depends on the reaction temperature, with borylated phenanthrenes obtained at 60 °C and phenanthrene‐fused borylated cyclobutanes formed at 0 °C. Based on DFT calculations, a mechanism for these novel transformations has been proposed, which involves an uncommon skeletal rearrangement, including migration of a methyl group and alkyne fragmentation, unprecedented in BCl 3 ‐promoted cyclization reactions.
Topics & Concepts
MetalChemistryOrganic chemistryOrganoboron and organosilicon chemistryCatalytic Cross-Coupling ReactionsCatalytic C–H Functionalization Methods