Tandem Knoevenagel–Michael-cyclocondensation reactions of malononitrile, various aldehydes and dimedone using acetic acid functionalized ionic liquid

A green one-pot three-component synthesis of tetrahydrobenzo[b]pyran and 3,4-dihydropyrano[c]chromene derivatives using a Fe3O4@SiO2–imid–PMAn magnetic nanocatalyst under ultrasonic irradiation or reflux conditions

“…The conventional synthetic method for the preparation of tetrahydrobenzo[b]pyran derivatives is a three-component reaction of cyclic 1,3-diketones, aryl aldehydes, and activated methylene compounds under various reaction conditions, e.g., in the presence of piperidine and triethylamine in acetic acid or DMF [12]. Other methods include use of microwaves [13], ultrasonic radiation [14], and electrogenerated base [15] or usingsome catalysts such as triethylbenzylammonium chloride (TEBA) [16],perfluorooctanoate [17],(S)-proline [18],silica bonded n-propyl-4-aza-1azoniabicyclo[2.2.2]octane chloride [19],n-TiO 2 /H 14 [NaP 5 W 30 O 110 ] [20],nanozeoliteclinoptilolite [21],SO 3 H-bearing carbonaceous solid catalyst (PEG-SAC) [22],Multi-walled carbon nanotube supported Fe 3 O 4 nanoparticles [23],Free-ZnO nanoparticles [24],acetic acid functionalized imidazolium salts [25],Nano α-Al 2 O 3 supported ammonium dihydrogenphosphate (NH 4 H 2 PO 4 /Al 2 O 3 ) [26]and amino functionalized ionic liquids [27]. However, these methods show varying degrees of success as well as limitations such as long reaction times, low yields, and use of toxic solvents.…”

Preparation of neutral ionic liquid [2-Eim] OAc with dual catalytic-solvent system roles for the synthesis of 2-amino-3-cyano-7-hydroxy-4-(aryl)-4H-chromene derivatives

“…In addition, C-O is observed at 1267 and 1053 cm −1 . To prove that this peak corresponds to the hydrogens of N-H in the compound, we also ran the 1 H NMR spectra of the starting material for the preparation of the ionic liquid ([2-Eim] OAc and CH 3 CO 2 H) in DMSO-d 6 where in the peaks of the hydrogens of [2-Eim] OAc and CH 3 CO 2 H were observed in 10.54, and 11.2 ppm, respectively. The difference between the peaks of the hydrogens in the compounds confirmed that the peak observed in 10 …”

“…During the last years, ILs have gained considerable attention for a broad range of different applications, including synthesis and catalysis [6] and bio catalytic reactions [7], separation processes [8], electrochemical applications [9], lithium secondary batteries [10], fuel cell [11], and dye-sensitized solar cells [12], nano-materials [13], polymer science [14], biomass processing [15] or lubricants [16], with some processes operating at industrial scale [17,18]. Chromene derivatives are an important class of compounds, widely present in plants, including edible vegetables and fruits [19].…”

A cesium fluoride promoted efficient and rapid multicomponent synthesis of functionalized 2-amino-3-cyano-4H-pyran and spirooxindole derivatives

“…Therefore, numbers of good methods were reported, amongst them, the more interesting and impressive involves the synthesis of 2-amino-3-cyano-4H-pyran [14][15][16][17] and spirooxindoles [18]. Owing to their medicinal utility, some reports on the multicomponent entries to 2-amino-3-cyano-4H-pyran and spirooxindoles appeared employing various catalysts [19][20][21][22][23][24][25][26][27][28][29].…”