Regioselective construction of 1,3-diaryl tetrahydroindazolones via the three-component reaction of 1,3-cyclohexanediones, β-nitrostyrenes and arylhydrazines

FeO(OH)@C-Catalyzed Selective Hydrazine Substitution of p-Nitro-Aryl Fluorides and their Application for the Synthesis of Phthalazinones

An efficient hydrazine substitution of p-nitro-aryl fluorides with hydrazine hydrates catalyzed by FeO(OH)@C nanoparticles is described. This hydrazine substitutions of p-nitro-aryl fluorides bearing electron-withdrawing groups proceeded efficiently with high yield and selectivity. Similarly, hydrogenations of p-nitro-aryl fluorides containing electron-donating groups also smoothly proceeded under mild conditions. Furthermore, with these prepared aryl hydrazines, some phthalazinones, interesting as potential structures for pharmaceuticals, have successfully been synthesized in high yields.

Tandem grinding reactions involving aldol condensation and Michael addition in sequence for synthesis of 3,4,5-trisubstituted isoxazoles

A one-pot, base-catalyzed, tandem grinding process involving carrying out aldol condensation and Michael addition in sequence to produce 3,4,5-trisubstituted isoxazoles from 3,5-dimethyl-4-nitroisoxazole, aromatic aldehydes and activated methylene compounds has been developed. In the presence of 10 mol% of pyrrolidine, aldol condensations of 3,5-dimethyl-4-nitroisoxazole with various aromatic aldehydes were performed with 3–10 minutes of grinding to provide 5-styryl-3-methyl-4-nitroisoxazoles in good to quantitative yields without further purification. Then, Michael additions between 5-styryl-3-methyl-4-nitroisoxazoles and activated methylene compounds (including ethyl 2-nitroacetate and alkyl 2-cyanoacetates) were carried out in the presence of 10 mol% of Et₃N in the same mortar with 3–5 minutes of continuous grinding to produce 3,4,5-trisubstituted isoxazoles in good to excellent yields.

3,4,5-Trisubstituted isoxazoles were prepared, using a tandem grinding strategy, from aromatic aldehydes, 3,5-dimethyl-4-nitroisoxazole and activated methylene compounds in the presence of pyrrolidine and Et₃N with high yields and efficiency.