Angewandte Chemie International Edition ( IF 12.102 ) Pub Date : 2018-01-03 , DOI: 10.1002/anie.201711816 Raphael Bigler, Varinder K. Aggarwal
A new strategy for the coupling of a broad scope of electronically diverse aromatics to boronic esters is reported. The coupling sequence, which relies on the directed ortho-lithiation of chromium arene complexes followed by boronate formation and oxidation, occurs with complete ortho-selectivity and enantiospecificity to give the coupling products in excellent yields and with high functional group tolerance. An intermediate chromium arene boronate complex was characterized by X-ray, NMR, and IR experiments to elucidate the reaction mechanism.
The C(sp2)–C(sp3) coupling of chromium arene complexes with boronic esters is reported. After ortho-selective lithiation of the aromatic and boronate formation, oxidation at the electron-rich chromium center with I2 triggers the 1,2-migration and Bpin elimination to directly afford the decomplexed ortho-coupled products in high yield and with complete enantiospecificity.