Practical, ecofriendly, and highly efficient synthesis of 2-amino-4H-chromenes using nanocrystalline MgO as a reusable heterogeneous catalyst in aqueous media

Efficient tandem synthesis of a variety of pyran-annulated heterocycles, 3,4-disubstituted isoxazol-5(4H)-ones, and α,β-unsaturated nitriles catalyzed by potassium hydrogen phthalate in water

“…Several synthetic methods have been widely applied for synthesis of pyran-based heterocyclic compounds, using many homogeneous or heterogeneous organic, inorganic, and nanomaterial catalysts, for example hexamethylenetetramine (HMT) [40], heteropolyacid [41], diammonium hydrogen phosphate [42], DBU [43], piperidine [44][45][46][47], tetrabutylammonium bromide (TBAB) [48], ionic liquids [49], morpholine [50], 4-(dimethylamino)pyridine (DMAP) [51], urea [52], 3-hydroxypropanaminium acetate (HPAA) [53], N-propylpiperazine sodium n-propionate (SBPPSP) [54], silica gel [55], sulfonic acid-functionalized silica [ [60], meglumine [61], I 2 /K 2 CO 3 [62], cetyltrimethylammonium bromide (CTABr) [63], nano-sized MgO [64], nano-structured Na 2 CaP 2 O 7 [65], NaHCO 3 [66], Na 2 CO 3 [67], triazine-functionalized ordered mesoporous organosilica [68], potassium phosphate tribasic trihydrate [69], Mg/Al hydrotalcite [70], Amberlyst A21 [71], DABCO [72], CeO 2 /CaO nanocomposite oxide [73], triton B [74], tetrabutylammonium chloride (TBAC) [75], nano-eggshell powder [76], basic alumina [77], [bmim]OH [78,79], LiBr [80], glycine [81], silica nanoparticles [82], ionic liquid choline chlorid...…”

Preparation of 2-amino-5,7-dimethoxy-4-aryl/alkyl-4 H -chromene-3-carbonitriles using Na 2 O-Al 2 O 3 -P 2 O 5 glass–ceramic system

“…Consequently, several methods have been reported for the preparation of chromene derivatives involve multi-component reaction of aldehydes, malononitrile and β-keto esters, diverse enolizable C-H activated acidic compounds, phenols and α-and β-naphthols [16----M a n u s c r i p t 21]. To achieve this aim several methods using different homogeneous [16][17][18][19] and heterogeneous [20][21][22][23] catalysts were explored.…”

“…To achieve this aim several methods using different homogeneous [16][17][18][19] and heterogeneous [20][21][22][23] catalysts were explored. These methods have the advantages of high yields, and mild reaction conditions and some disadvantages of using toxic solvents and expensive catalysts.…”

Kinetic Aspects of Tetrahydrobenzo[b]pyran Formation in the Presence of Agar as a Green Catalyst: A Mechanistic Investigation

“…MCRs have an outstanding status in medicinal chemistry and modern organic synthesis because they are one-pot processes that assemble three or more components 1,2 .…”