Monovalent aluminum(i) species was successfully stabilized using a reduced phosphomolybdate scaffold as a dual-acid catalyst for a four-component domino reaction.
Fe 3 O 4 @SiO 2-CeCl 3 catalyzed chemoselective synthesis of functionalized 3-substituted-1,5-benzodiazepines via one-pot multicomponent and domino reactions has been developed. During the one-pot synthesis process, one new cycle and four new bonds (one CC , two C-N and one C=C) were constructed by the nucleophilic addition and eliminate reaction (dehydration etc.) process, intramolecular proton transfer and cyclization process. The major advantages of the present method are good to excellent yields, shorter reaction time, simple experimental procedure, easy work up, mild reaction conditions, recyclability of the catalyst and ability to tolerate a variety of functional groups which gives economical as well as ecological rewards. K E Y W O R D S 3-substituted-1,5-benzodiazepines, catalysis, domino reaction, Fe 3 O 4 @SiO 2-CeCl 3 , one-pot multicomponent
12 novel substituted 3,4-diethoxycarbonyl-2-(thiazol-2-yl)benzo[b][1,4]diazepines were obtained via a domino sequence of a nucleophilic addition/dehydration/cyclization/H + shift. These reactions were achieved by reacting substituted 1,2-phenylenediamines, 2-thiazolecarboxaldehyde with diethyl acetylenedicarboxylate in EtOH. Benzo[b]-[1,4]diazepines of the two structures of imine structure and enamine structure were found in this reaction process due to chem-/regio-selectivity. The influence of reaction conditions on the selectivity of target products was also studied in detail. The selectivity law of synthesis reaction was obtained, and the yield of single product was maximized. A simple synthesis strategy for the selective synthesis of benzo[b][1,4]diazepines was provided. To understand the reaction mechanism and further prove the conclusion, quantum chemical calculations were performed, and density functional theory (DFT) studies based on B3LYP method and 6-31G basis set were employed to carry out the study. Natural bond orbital (NBO) charge analysis of the substituted 1,2-phenylenediamine was carried out to justify the selective attack at the nucleophilic centers. NBO charge analysis of the target compounds was carried out to explain the stability of benzo[b][1,4]diazepine isomers with imine or enamine structure. Moreover, the plausible reaction mechanism was proposed.
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