An expeditious and greener one-pot synthesis of 4H-chromenes catalyzed by Ba(OTf)₂in PEG-water

Abstract

An expeditious synthesis of 4H-chromenes has been achieved by three-component one-pot condensation of 1,3-diketone, aldehyde, and malononitrile using Ba(OTf) 2 as catalyst in PEG-water at room temperature. Results from various reaction media and different metal triflates as catalysts show that choice of proper catalyst and the solvent system play a key role in the synthesis of 4H-chromene-3-carbonitrile derivatives. The catalyst can be recovered and reused at least five times without loss of activity. The application of an eco-friendly, noncorrosive, and reusable catalytic system with high isolated yield of the products makes this method advantageous.

Efficient metal-free green syntheses of 4H-chromenes and 3-amino alkylated indoles using a reusable graphite oxide carbocatalyst under aqueous and solvent-free reaction conditions

“…In 2011, Chen and co-workers reported the asymmetric synthesis of 2-amino-4-(indol-3-yl)-4 H -chromenes. 63 Recent reports include catalysts such as (BaOTf) 2 , 64 l -proline, 65 Nano ZnO, 66 LCMNPs, 67 β-cyclodextrin, 68 amberlite IRA-400 Cl, 69 and Fe 3 O 4 @chitosan. 70 Similarly, for 3-amino alkylated indoles, recent reported methodologies include l -proline, 71 SDS, 72 iron( iii ) phosphate, 73 β-cyclodextrin, 74 PMA–SiO 2 , 75 silver triflate, 76 bromodimethylsulfonium bromide (BDMS), 77 PANI-HBF 4 , 78 ZrOCl 2 ·2H 2 O/CuCl 2 ·3H 2 O, 79 RGO/ZnO, 80 and cellulose sulfonic acid.…”

PEG-SO3H promoted one pot grinding method for the synthesis of 2-amino-4H-chromene-3-carboxylates

“…Earlier 2-amino-4H-chromene com-pounds was reported using potassium pthalimide catalyst (Kiyani and Ghorbani, 2014). Shujiang reported the derivatives of 4H-chromenes under microwave irradiation without catalyst, In addition, several homo and heterogeneous catalysts (Figure 2) such as Ferric hydrogen sulphate (Eshghi et al, 2011), silicagel supported phosphoric acid (Davoodnia et al, 2011), Ba(otf)2 (Kumar and Rao, 2012),CuSo 4 .5H 2 0 (Behbahani and Maryam, 2013),DABCO (Jain et al, 2014), DMAP (Khan et al, 2011), Lithium bromide (Sun et al, 2010), Amberlyst A-21 (Yadav et al, 2007) and amino acids like Glycine (Datta and Pasha, 2012), L-proline (Guo et al, 2007) also used to synthesized the 4Hchromene compounds. However, these protocols are suitable for the synthesis of compounds but facing some limitations such as reaction time, reaction conditions, dif icult workup, product yields, costly organic solvents and highly expensive catalysts.…”

Synthesis and Biological Evaluation of Novel 1‐(4‐(Hydroxy(1‐oxo‐1,3‐dihydro‐2H‐inden‐2‐ylidene)methyl)phenyl)‐3‐phenylurea Derivatives

“…High reactivity of 1,3‐diketones allow molecular diversity in the synthesis of organic and natural compounds. For example, pyrazoles, [ ][ ] pyrroles, [ ][ ] pyrimidines, [ ][ ] furans, [ ][ ] chromenes, xanthenes, [ ][ ] isocoumarins, [ ][ ] pyranones and sulfur‐containing heterocycles can be synthesized from the 1,3‐diketones. In the literature, 1,3‐diketones have been reported as having potential uses as catalyst, anticancer I, antibacterial II, antifungal, antioxidant III ( Fig.…”