Transition-metal-free C-H arylation of unactivated arenes with aryl halides enabled by potassium tert-butoxide/gatifloxacin hydrochloride catalyst

Abstract

A transition-metal-free protocol for the efficient construction of biaryl frameworks via direct C–H arylation of unactivated arenes with aryl halides is reported, enabled by a synergistic potassium tert-butoxide (t-BuOK)/gatifloxacin hydrochloride (L6) catalytic system. This method allows the direct coupling of aryl iodides and bromides with arenes or pyrazine to afford (hetero)biaryls in good to excellent yields. Notably, the protocol exhibits broad functional-group tolerance and high chemoselectivity, and is applicable to gram-scale synthesis and intramolecular cyclization, while obviating the need for prefunctionalized organometallic reagents. Mechanistic investigations support a base-promoted homolytic aromatic substitution (BHAS) pathway involving single-electron transfer. Overall, this work provides an attractive and practical alternative to conventional cross-coupling strategies for accessing structurally diverse (hetero)biaryl scaffolds.