Recent Advances in Room-Temperature Direct C–H Arylation Methodologies

Abstract In recent decades, direct C–H arylation has become a preferred tool for biaryl coupling over traditional cross-coupling methods owing to its operationally simple protocol, inherent atom and step economy, reduced metallic waste. Several elegant have been developed that offer the facile transformation of usually inert Csp2–H bonds into Csp2–Csp2 in single synthetic operation. Despite many merits, major drawback this chemistry comes from low reactivity aryl bonds, which often mandate harsh reaction conditions compromising sustainability. Hence, developing protocols require milder an important goal area research. This review article comprehensively highlights synthesis mechanistic aspects reactions, proceed at or below room temperature. 1 Introduction 2 Concepts Examples 2.1 Transition-Metal-Catalyzed Procedures 2.1.1 Pd Catalysis 2.1.2 Other Metal-Based 2.1.3 Additive-Free 2.2 Direct Arylation Polymerization 2.3 Photocatalyzed 2.3.1 Organometallic C–H-Activation-Based 2.3.2 Radical-Addition-Based 2.4 Transition-Metal-Free 2.4.1 Base-Mediated 2.4.2 Iodonium- Diazonium-Salt-Based 2.5 Electrocatalyzed 3 Summary Outlook