ZIF@ZnTiO3 Nanocomposite as a Reusable Organocatalyst for the Synthesis of 3, 4-dihydropyrano[c]chromene Derivatives

Background: Dihydropyrano [3, 2-c]chromenes and their derivatives have great attention for scientists. They have different activities such as biological properties, spasmolytic, diuretic, anticoagulant, anti-cancer, and anti-anaphylactic activity. For these vary biological activities, chromene derivatives have made significant for further progress in medicinal and organic synthesis studies. So, in view of the importance of chromenes, we aimed to synthesis of 3, 4-dihydropyrano [3, 2-c] chromene derivatives. ZIF@ZnTiO3nanocomposite as organocatalyst was used. Method: An effective and applicable technique was used for preparation of 3, 4-dihydropyrano [3, 2- c] chromene derivatives. Dihydropyrano [c] chromenederivatives were prepared by using ZIF@ZnTiO3compositeas a recyclable catalyst. One-pot three-component reaction of aromatic aldehydes, malononitrile, and 4-hydroxycoumarin was done for synthesis of dihydropyrano [c] chromenederivatives over composite catalyst with excellent yields. The as prepared dihydropyrano [c] chromenederivatives were measured by melting point, FTIR, 1H NMR, and 13C NMR. The nano catalyst could be recycled several times. Result: A novel nano catalyst of MOF containing Mn2+ ions and 2- methyl imidazole (ZIF) and zinctitanate (ZIF@ZnTiO3) composite was prepared. The synthesized organocatalyst was studied for preparation of 3, 4-dihydropyrano [3, 2-c] chromene derivatives. One-pot three-component reaction of aromatic aldehydes, malononitrile, and 4-hydroxycoumarin was done for synthesis of dihydropyrano [c] chromene derivatives over composite catalyst with excellent yields. The reaction was optimized. Conclusion: The organocatalyst composite of consist of ZIF and zinctitanate was prepared. The ZIF@ZnTiO3 was used as catalyst for synthesis of 3, 4-dihydropyrano [3, 2-c] chromene derivatives via one-pot three-component condensations of aromatic aldehydes,malononitrile, and 4 hydroxycoumarin. The results of melting point, FTIR, 1H NMR, 13C NMR also confirmed the formation of high yield of 3, 4-dihydropyrano [3, 2-c] chromene derivatives at short time. The appealing properties of this method are environmentally friendly, mild reaction conditions (low reaction time and high yields of pure products), easy work up and recyclability of reaction catalyst.