Fig. 1: Design of an organocatalytic transisopropenylation approach for the synthesis of IPPEs from alcohols.

a Organocatalytic transisopropenylation enables the straightforward synthesis of IPPEs from hydroxyl-group-containing complex drugs (e.g., PTX), functional building blocks, and polymers under mild reaction conditions, complementing traditional approaches that are limited by the poor functional group compatibility and harsh reaction conditions. The resulting IPPEs will facilitate the synthesis of medicinally valuable ketals, such as modular ketal-linked prodrugs and biomaterials. b Organocatalytic transisopropenylation of alcohols, using 2-MPE with catalysis by Brønsted acid–base pair. Alcohol is transisopropenylated via the MOP ketal and transient oxocarbenium ion. c Optimization of the Brønsted acid–base pair organocatalyst. General conditions: 1a (1.0 mmol, 1.0 equiv., 0.5 M), 2a (16.0 equiv.), 0.5 mol % catalyst, THF, 25 °C, 1.0 h. The conversion rate of 1a and molar ratio of 3a to 3a′ were determined by NMR.