Synthesis and in vitro antifungal activity of new Mannich bases derived from 2-hydroxy-1,4-naphthoquinone (Lawsone)

Using the same previous procedure, the reaction of the aldehyde N-phenyl-1,2,3-triazole (6) with lawsone and the amines 7 and 8, was performed. Unfortunately, rather than obtaining the Mannich adducts 9, in this reaction was obtained exclusively the compound 10 and 11 (Scheme 2). Scheme 2. Synthesis of N-phenyl-1,2,3-triazole derivatives. Compounds 10 and 11 were achieved through Michael addition in the respectively Mannich adducts formed in situ and occur due to the very low reactivity of the aldehyde triazolic 6 compared to the aldehydes used in preparation of adducts 2-4. The synthesized compounds (2-4, 10 and 11) were evaluated for their in vitro antifungal activity against for C. albicans (ATCC 14053), C. glabrata (ATCC 2001) and C. krusei (ATCC 34135).