Metal-free O–H insertion enables access to heterocycle-rich α-carbonyloxy esters

Abstract

α-Carbonyloxy esters are key structural motifs in bioactive compounds; however, their selective synthesis without metals remains a challenging task, especially in heterocyclic systems bearing reactive sites. Herein, we report a metal and oxidant-free method for synthesizing α-carbonyloxy esters through highly selective O–H bond insertion of aryldiazoacetates with (hetero)carboxylic acids. The transformation occurs under mild thermal conditions and has remarkable selectivity for O–H functionalization in the presence of competing N–H and active C–H bonds. A wide range of substrates, including indole, quinoline, pyrimidine, thiophene, and thiazole derivatives, are well tolerated, affording the desired products in up to 93% yield.