Abstract: 1,5-Benzadiazepines and their derivatives are a very important class of nitrogen-containing heterocyclic compounds with biological activity that are widely used in medicine. The traditional procedure for the synthesis of these compounds is a one- pot condensation between 1,2-phenylenediamine (I) and ketones. However, a large number of catalytic systems reported in the literature, suffer from several drawbacks such as the use of a large amount of catalysts, unsatisfactory product yields and problems of product isolation procedures. In recent years, the use of metal-organic frameworks (MOFs) as heterogeneous catalysts has attracted great interest in organic synthesis because their structural, textural and acidic properties can be controlled at the molecular or atomic level. Herein we report the use of MOFs as a recyclable green catalyst for the synthesis of 1,5-benzodiazepines from 1,2-phenylenediamine and ketones (acetone, acetophenone and methyl ethyl ketone). The main attention was focused on the investigation of the dependence of catalytic properties on the type of metal ions for isostructural MOFs of the families MIL-100(M) (M: V3+, Al3+, Fe3+ and Cr3+) and three porous aluminium trimesates Al-BTCs (MIL-96(Al), MIL-100(Al) and MIL-110(Al)). Reactions were carried out at 50 °C with an acetone/(I) molar ratio of 2.5 and 4.0 in different solvents (methanol, ethanol, acetonitrile, 1,2-dichloroethane) and under solvent free conditions. It was found that yield of 1,5-benzodiazepine decreases with decreasing solvent polarity. The maximal yield of 1,5-benzodiazepine was observed in methanol, a solvent with large relative polarity. A combination of catalytic, theoretical and physicochemical methods showed that reaction rates and yields of 1,5-benzodiazepines are adjusted by the type of metal ions and accessibility of active sites (Table 1). Recycling experiments point that yield of (III) does not change during at least three and six catalytic cycles for MIL-100(V) and MIL-100(Al), respectively.

Cite: Timofeeva M.N. , Panchenko V.N. , Jhung S.H.
Metal-Organic Frameworks as Efficient Catalytic Systems for Synthesis of 1,5-Benzodiazepine Derivatives Both in Solution and Under Solvent-Free Conditions
In compilation ChemTrends-2018 : Сборник тезисов докладов Международной научной конференции «Органические и гибридные функциональные материалы и аддитивные технологии», 23–28 сентября 2018 г., Москва. – МАКС Пресс,., 2018. – C.39. – ISBN 9785317059323. РИНЦ

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