Tailoring Benzylic C(sp 3 ) H Bond Functionalization Strategies of Benzyl Alcohols: A Review on Selective Catalytic Approaches for Synthesis of Benzoxa
Vijayalaxmi S. Swanne, Pavankumar N. Nagtilak, Minakshi G. Kalshetti, Vikas D. KaduThe advancements in the C(sp 3 ) H bond functionalization of benzyl alcohol as innovative and sustainable approach has been an attention in the organic transformations. The direct synthesis of benzoxazoles from benzyl alcohols and 2‐aminophenols via C(sp 3 ) H bond functionalization has emerged as an atom‐economical and sustainable alternative to traditional protocols. This review systematically summarizes recent advances in homogeneous and heterogeneous catalytic strategies for the synthesis of benzoxazoles, encompassing transition‐metal‐catalysis, metal‐free catalysis, organocatalysis, acceptor‐less dehydrogenative catalysis, photocatalysis, metal–organic framework catalysis, nanocatalysis, electrocatalysis, and flow chemistry approaches. The influence of catalyst composition, ligand design, oxidant choice, and reaction parameters on yield, selectivity, and functional group tolerance is critically analyzed. Also, the comparative mechanistic insights highlight common pathways involving alcohol oxidation to aldehyde, imine condensation, cyclization to dihydrobenzoxazole, and oxidative aromatization, as well as notable deviations under specific catalytic conditions. Equally, the particular emphasis is placed on Cu, Fe, Co, Ni, Ru, Pd, and Mn‐based systems, along with organocatalytic and heterogeneous approaches. The trends in substrate electronic effects, catalyst recyclability, and green chemistry metrics are conferred to the direction of future developments. This review aims to provide a comprehensive resource for designing efficient, sustainable, and broadly applicable protocols for benzoxazole synthesis from benzyl alcohols.