A revisit to the Gattermann reaction: interesting synthesis of nitrogen heterocyclic aromatic halides and their fluorescence properties

A Gattermann reaction and electrophilic substitution that were simultaneously conducted in an one-pot reaction are reported. 2-Chloro-5-(3-chloro-4-methoxyphenyl)-1,3,4-thiadiazole and three similar aromatic halides were facilely synthesized from 2-amino-5-(4-methoxyphenyl)-1,3,4-thiadiazole, 2-amino-5-(4-methoxyphenyl)-1,3,4-oxadiazole, and 3-amino-5-(4-methoxy-phenyl)-4H-1,2,4-triazole. In this process, not only was the amino-group on the heterocyclic ring substituted with a halogen atom but also the hydrogen atom on the benzene ring was substituted. The mechanism for the above transformation was suggested too. Moreover, the fluorescence properties of the compounds were systematically investigated.