Multicomponent Synthesis of Novel 1,2,3-triazolic thionaphthoquinones

Naphthoquinones are a class of substances widely found in nature and well explored in literature, mainly because of their diverse biological profiles. In this context, we highlight the 2-hydroxy-3-phenylsulfanylmethyl-[1,4]-naphthoquinones, which have already been described with antimalarial1, antileishmanial2, antibacterial3 and trypanocidal4 activities. Similarly to naphthoquinones, 1H-1,2,3-triazoles have a remarkable relevance due to their varied biological activities. The objective of this work is the multicomponent synthesis of novel thionaphthoquinones containing a 1H-1,2,3-triazolic nucleus. The synthetic strategy involves the formation of different triazolic aldehydes, starting from aromatic anilines (1) in a diazotization reaction followed by nucleophilic aromatic substitution, forming azides (2). These are transformed into triazolic alcohols (3) through a copper-catalyzed 1,3-dipolar cycloaddition reaction. Finally, the triazolic aldehydes (4) are obtained by oxidation of the corresponding triazolic alcohols.5 Synthesis of triazolic thionaphthoquinones (6) occurs through Knoevenagel condensation, followed by 1,4-nucleophilic addition between lawsone (5), triazolic aldehydes and thiols with varied pattern of substitution.1