10.1039/d1cc01778k
The research focuses on the development of a novel Rh(III)-catalyzed cascade reaction involving C–H activation, ring-opening C–C bond cleavage, and cyclization of carboxylic acids with cyclopropanols to synthesize 3-substituted phthalides and a,b-butenolides. This reaction exhibits excellent functional group tolerance and operates under relatively mild conditions, which is significant for the late-stage functionalization of bioactive compounds. The experiments involved optimizing the reaction conditions using ortho-methylbenzoic acid and 1-phenylcyclopropan-1-ol as model substrates, with the best yield achieved using [Cp*RhCl2]2/AgOAc, Cs2CO3, and 4 ? MS in CH3CN solvent at 80°C. The scope of the reaction was explored with various aryl- and alkyl-substituted cyclopropanols and carboxylic acids, yielding the desired products in modest to good yields. Mechanistic studies included kinetic isotope effect experiments, deuterium incorporation experiments, and the examination of potential intermediates, leading to a proposed mechanism involving rhodacycle formation, β-C elimination, β-H elimination, and migratory insertion steps.