Open vessel and cooling while heating microwave-assisted synthesis of pyridinyl N-aryl hydrazones.

We reported the first example of open vessel and cooling while heating microwave-assisted synthesis of pyridinyl N-aryl hydrazones. Compounds were prepared in excellent isolated yields (88-98%) in only 5 min, by reacting 4- and 2,4-(di)substituted phenylhydrazines, bearing both electron-donating (4-CH₃, 4-OCH₃) and -withdrawing (4-Cl, 4-Br, 4-CF₃, 4-NO₂, 2,4-Cl₂) groups with 2-, 3-, and 4-acetylpyridine. The method was successfully extended to other carbonyl compounds.