Mechanochemical Intramolecular C(sp ³ )–H/C(sp ² )–H Coupling for Synthesis of Acridine and Anthracene Skeletons

Direct C–H/C–H coupling represents an attractive strategy for efficient carbon–carbon bond formation; however, the selective activation of unactivated C–H bonds remains a significant challenge. Here we report a mechanochemical approach to intramolecular C(sp3)–H/C(sp2)–H coupling using a potassium/ferrocene system, enabling the rapid synthesis of acridine and anthracene frameworks from unactivated substrates within 30 min of ball milling. The results reveal a unique interplay between alkali metals and ferrocene and provides a new platform for C(sp3)–H/C(sp2)–H coupling.