Abstract
Background: In recent years, an increasing interest has been focused on the synthesis of 2-substituted 1,3-indandione compounds owing to their significant biological activity. It is well known that indandione and related compounds exhibit a wide range of biological activities such as antitumor, anticancer, sedative, hypotensive and neuromuscular blocking activities. The synthesis of various 2-substituted-1,3-indandiones has initially been stimulated by their known anticoagulant and pharmacological properties. As a very strong electron acceptor, 1,3-indandione is a part in new dipolar molecules exhibiting interesting optical properties and used as dopants in novel functional materials.
Methods: A mixture containing aldehyde, 1,3-indandione, indole and [BDBDIm]Br were heated at 80°C for the required reaction times. The progress of the reaction was monitored by TLC (EtOAc: petroleum ether 1:3). After completion of the reaction, the product was extracted with CHCl3/H2O and preferred the organic phase. After evaporation and recrystallization, the pure product was obtained. The aqueous phase was evaporated also to produce recycled bis ionic liquid [BDBDIm]Br. The identity and purity of the products were confirmed by IR, 1H NMR, 13C NMR and elemental analysis. Results: In continuation of our ongoing studies to synthesize of heterocyclic and pharmaceutical compounds at mild and practical protocols, herein we wish to report our experimental results on the synthesis of new generation of 1,3-indandione using various aromatic aldehydes, indole, 1,3-indandione in the presence of novel bis ionic liquid ([BDBDIm]Br) and the results were listed. After reaction, the bis ionic liquid is easily separated from the reaction medium by washing with distilled water (IL is soluble in water). The washed bis ionic liquid is distilled under vacuum to recover solvent for reuse in subsequent reactions. Our experiments also indicated that after six runs, the catalytic activities of the reagents were almost the same as those of fresh catalysts Conclusion: Finally, we develop an efficient and convenient procedure for the synthesis of 1,3- indandiones through three component synthesis of aldehydes, indole and 1,3-indandione catalyzed by [BDBDIm]Br as a reusable ionic liquid as catalyst. The remarkable advantages offered by this method are: catalyst is inexpensive, non-toxic, easy handling and reusable, simple work-up procedure, short reaction time, high yields of product with better purity and green aspect by avoiding toxic catalyst and hazardous solvent. Apart from the mild conditions of the process and its excellent results, the simplicity of product isolation and the possibility to recycle the catalyst offer a significant advantage. To the best of our knowledge this is the first report on synthesis of 1,3-indandiones using ionic liquid 3, 3-(butane- 1,4-diyl) bis (1,2-dimethyl-1H-imidazole-3-ium) bromide.Keywords: Multicomponent, 1, 3-indandione, indoles, [BDBDIm]Br.
Graphical Abstract
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