Solvent-controlled catalytic divergent C–H alkylation of quinolones driven by unusual DMSO-promoted 1,3-heteroarene migration†

We report on a catalytic divergent C–H alkylation of 4-quinolones with diazo compounds where the reaction pathways are controlled by a reaction solvent. Cp*Rh(iii)-catalyzed site-selective C–H alkylation was carried out in dichloromethane to produce C2-alkylated 4-quinolones. C(2)–H alkylation and sequential [1,3]-heteroarene rearrangement were achieved by utilizing EtOH/DMSO solvent in the same catalytic system at 70 °C, allowing valuable 4-quinolones bearing an all-carbon quaternary center at the 2-position to be efficiently synthesized in a one-pot operation. By combining experimental results and computational studies, we propose an unprecedented DMSO-promoted Truce–Smiles rearrangement.