Condition-Controlled Regio- and Chemoselective Allylic Alkylation of 2-Substituted Quinolin-4-ones with MBH Carbonates

Condition-switchable, regiodivergent <i>O</i>-, <i>N</i>-, and <i>C</i>-allylation of quinolin-4-ones with Morita-Baylis-Hillman (MBH) carbonates is disclosed. Systematic modulation of the Lewis/Brønsted base catalyst and solvent enables programmable site-selectivity: γ-<i>O</i>-allylation proceeds exclusively under condition A (10 mol % DABCO, CH₂Cl₂, 25 °C), whereas α-<i>O</i>-allylation is favored under condition B (10 mol % K₂CO₃, DMF, 80 °C); subsequently, <i>N1</i>- and <i>C3</i>-allylations are achieved under condition C (20 mol % DMAP, <i>t</i>-BuOH, 80 °C) and conditions D (10 mol % DABCO, DCE, 100 °C), respectively. The protocol features broad substrate scope, high yields (up to 99%), and excellent selectivity. Mechanistic studies support <i>O-</i>to-<i>N</i> and <i>O</i>-to-<i>C</i> rearrangement pathways for <i>N1</i>- and <i>C3</i>-products, respectively. This operationally simple method provides a practical platform for late-stage diversification of medicinally relevant quinolin-4-ones.