Expeditious Green Synthesis of Novel 4-Methyl-1,2,5,6-tetraazafluoranthen-3(2)-one Analogue from Ninhydrin: N/S-Alkylation and Aza-Michael Addition.

A straightforward green synthesis of 4-methyl-1,2,5,6-tetraazafluoranthen-3(2)-one is reported from ninhydrin via condensation with ethyl acetoacetate, followed by cyclization with hydrazine hydrate in water as a benign solvent. Tetraazafluoranthen-3-thione was obtained using Lawesson's reagent. N-alkylated tetraazafluoranthen-3-one and S-alkylated analogues were synthesized via alkylation. The investigation of the unique reactivity of 4-methyl-1,2,5,6-tetraazafluoranthen-3(2)-one/thione toward the alkylation and aza-Michael additions was explored.