Bench-Stable Cerium(IV) Benzoate: A Versatile LMCT Catalyst for Selective Dehydroxymethylative Functionalization

Dehydroxymethylation
offers intriguing synthetic opportunities
to exploit the ubiquitous C–C bonds in free alcohols as unconventional
functional handles; however, its synthetic potential has been constrained
by the development of efficient catalysts. In this work, we introduce
a robust, bench-stable cerium(IV) benzoate complex, [Ce(TRIPCO2)5Na], which functions as an efficient ligand-to-metal
charge transfer (LMCT) catalyst, enabling selective cleavage of α-C(sp3)–C(sp3) bonds in free alcohols. This cerium(IV)
catalyst is straightforward to synthesize on a gram scale, providing
simple conditions for dehydroxymethylation reactions while eliminating
the need for exogenous halide additives. The catalytic efficiency
of this complex has been demonstrated in the dehydroxymethylative
amination of free alcohols and the seamless one-pot synthesis of N-alkyl pyrazoles. Furthermore, the cerium-LMCT catalyst
demonstrates efficacy within a metallaphotoredox paradigm, where the
synergistic interplay between cerium-LMCT and nickel catalysis facilitates
dehydroxymethylative alkylation, enabling the efficient utilization
of alcohol feedstocks for selective C(sp3)–C(sp3) cross-coupling reactions. Mechanistic investigations have
elucidated the photoexcitation and redox properties, revealing the
selective generation of alkoxy radical intermediates in the presence
of benzoate ligand, a critical factor in enabling radical-mediated
bond cleavage.