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ONE-POT SYNTHESIS OF 1,5-BENZODIAZEPINE-2,3-DICARBOXYLATES via THREE-COMPONENT DOMINO REACTIONS IN THE PRESENCE OF γ-Fe2O3@SiO2/Ce(OTf)3

Xiaoying An, Lei Gao, Mingliang Wang, Haitao Wu, Lanzhi Wang
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Abstract


Novel, efficient and environmentally friendly approaches have been developed for the synthesis of 1,5-benzodiazepine-2,3-dicarboxylates by
one-pot three-component domino reactions in the presence of a catalytic amount of γ-Fe2O3@SiO2/Ce(OTf)3 in EtOH at ambient temperature. A total of 32 2,5-dihydro-1H-1,5-benzodiazepine-2,3-dicarboxylates and 2-methyl-2,3-dihydro-1H-1,5-benzodiazepine-2,3-dicarboxylates with enamine or imine structure of the heterocycle, respectively, were obtained in good yields by reacting substituted 1,2-phenylenediamine, β-carbonyl esters, and ethyl glyoxylate or ethyl pyruvate. One-pot reactions were successfully realized to form one new cycle and four new bonds (one C–C, two C–N, one C=C or two C–C, one C–N, one C=N). Furthermore, plausible mechanisms for the formation of 1,5-benzodiazepine-2,3-dicarboxylates have been proposed. The salient features of this reaction include short reaction time, mild reaction conditions, moderate to excellent yields, recyclability of the catalyst, and wide substrate scope.

Keywords


1,5-benzodiazepine-2,3-dicarboxylates; 1,4-diazepines; γ-Fe2O3@SiO2/Ce(OTf)3; catalysis; domino reactions; multicomponent reactions

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