Metal-organic frameworks as efficient catalytic systems for the synthesis of 1,5-benzodiazepines from 1,2-phenylenediamine and ketones

- Synthesis of 1,5-benzodiazepines over MIL-100(M), MIL-110 and MIL-96 was studied.
- Effect of Brønsted and Lewis acidity on MIL's performance was investigated.
- Lewis acidity of MIL-100(Fe, Cr, Al, V) was studied by EPR spectroscopy.
- The type of M3+(Al, Fe, Cr, V) and structure of MILs affect the yield of product.
- MIL-100(M) samples perform well in compared with zeolites.

Benzodiazepines and their derivatives are a very important class of nitrogen-containing heterocyclic compounds with biological activity that are widely used in medicine. In this study, we demonstrated synthesis of 1,5-benzodiazepines from 1,2-phenylenediamine and ketones (acetone, cyclohexanone, acetophenone, methyl ethyl ketone) in the presence of isostructural porous metal-benzenetricarboxylates 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)). A combination of catalytic, theoretical and physicochemical methods showed that reaction rates and yields of 1,5-benzodiazepines were adjusted by the type of metal ions and accessibility of active sites. The yield of 1,5-benzodiazepines in the presence of MIL-100(M) was comparable with zeolites, such as HY, H-ZSM−5, β-zeolite and heulandite.

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