Recyclable ZnIn2S4 Microspheres for Photocatalytic Azolation of N-Heterocycles

A series of zinc indium sulfide (ZnIn2S4) were synthesized by solvothermal methods in different solvents. After characterizations, the ZnIn2S4 prepared in ethanol (i.e., ZIS-1) showed the highest photocurrent density. With the ZIS-1 as a photocatalyst, the direct C-H azolation of N-heterocycles including quinoxalin-2(1H)-ones, quinazoline, and 2H-benzo[b]-[1,4]oxazin-2-ones (32 examples) was realized in an air atmosphere under blue light (456 nm). More importantly, the microspherical photocatalyst ZIS-1 is stable in the catalytic process and can be used at least five times while the reactivity remains unchanged. In addition, this practical approach is also applicable to some other complex molecules of interest, such as ibuprofen and isoxepac.