Photoinduced transposed Paternò-Büchi reaction for effective synthesis of high-performance jet fuel

High-energy-density fuels are important for volume-limited aerospace vehicles, but the increase of the fuel energy density always leads to poor cryogenic performance. Herein, we investigated the transposed Paternò-Büchi reaction of biomass cyclic ketone and cyclic alkene to synthesize the new kind of alkyl-substituted polycyclic hydrocarbon fuels with high energy density and good cryogenic performance. The triplet-energy-quenching results and phosphorescent emission spectra reveal the sensitization mechanism of the reaction, including photosensitizer excitation, triplet-triplet energy transfer, cyclization and relaxation, and the possible reaction path was revealed by the DFT calculations. The reaction conditions of photosensitizer type and addition, molar ratio of substrates, reaction temperature and incident light intensity were optimized, with the target product yield achieving 65.5%. Moreover, the reaction dynamics of the reaction rate versus the light intensity is established. After hydrogenation deoxygenation reaction, three fuels with high density of 0.864-0.938 g·ml −1 and low freezing point of <−55 °C are obtained. This work provides a benign and effective approach to synthesize high-performance fuels.