New Synthesis of 2,4,6,8-Tetramethyl-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione Using Etidronic Acid as a “Green” Catalyst

Svetlana Yu. Panshina, Пономаренко Оксана Владимировна, А. А. Бакибаев, Victor S. Malkov

2020

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DOI 10.1134/s1070428020120039
Data confidence 70 medium
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Abstract

A new method has been developed for the synthesis of 2,4,6,8-tetramethyl-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione in 62% yield using etidronic acid [1-hydroxyethane-1,1-diylbis(phosphonic acid), HEDP] as a “green” catalyst. A plausible stepwise mechanism of the reaction has been proposed and partially confirmed by NMR data and studying model processes. The effects of the reaction medium and HEDP on particular species involved in the reaction, namely N,N′-dimethylurea, 4,5-dihydroxy-1,3-dimethylimidazolidin-2-one, and 2,4,6,8-tetramethyl-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione, have been studied by 1H and 13C NMR spectroscopy in D2O, neutral and acidified solutions (acetic acid-d4), and solutions containing 1 equiv of HEDP.