Air-stable azomethine ylides with an unusual pattern of charge distribution were efficiently prepared via the rhodium-catalyzed reaction between pyridines and 1-sulfonyl-1,2,3-triazoles. This reaction allowed for the first example of the catalytic multicomponent [5 + 2] cycloaddition reactions, thus resulting in the formation of biologically active 1,4-diazepine compounds.

Here we used AlCl 3 to transform tetrahydrotricyclopentadiene (THTCPD) into a high-energy-density liquid fuel. The reactant contains three inseparable isomers (I, II, and III). Quantum computation shows the possibility of endo fragments of THTCPD turning into exo counterparts. However, experiment indicates the isomerization only happens on norbornyl fragments but cyclopropyl fragments remain unchanged. Reactants I and II containing both norbornyl and cyclopropyl fragments are slowly isomerized, and the reactions are reversible, whereas III without a cyclopropyl fragment is converted quickly. The effects of the reaction conditions were studied. A 5% concentration of AlCl 3 shows enough catalytic activity. A temperature higher than 15 °C is not preferred because it lowers the equilibrium conversion. A halohydrocarbon solvent such as 1,2-dichloroethane is necessary. Pseudo-first-order reversible kinetics was established for the isomerization of I and II. The heat of reaction is 22.94 and 17.69 kJ/mol, respectively. The resulting mixture shows good potential for advanced propulsion due to its high energy content and low freezing point.

No abstract

A new photoredox-catalyzed chlorotrifluoromethylation reaction of internal arylalkynes under mild conditions using visible light has been developed. The reactions proceed with high levels of regio- and stereoselectivity and utilize commercially available CFSOCl as both the CF and Cl source. In the mechanistic pathway for this process, generation of the CF radical and chloride ion occurs by Ir(ppy)-photocatalyzed reductive decomposition of CFSOCl. The synthetically important trifluoromethyl-substituted vinyl chlorides produced in this process can be readily transformed to 1,1-bis-arylalkenes by using Suzuki coupling.

The direct oxidative addition of CF and HO to alkynes was achieved with photoredox catalysis to obtain α-trifluoromethyl ketones via rapid enol-keto tautomerization. The reaction exhibits high functional group tolerance and regioselectivity. Heterocycles of various sizes containing CF were synthesized from the α-CF-substituted diketones obtained through the protocol, thereby demonstrating the versatile applicability of the method. Mechanistic studies of the reaction with isotopes provided insight into the reaction pathway.