Synthesis and characterization of a series of 1,3,5-trisubstituted-2-pyrazolines derivatives using methanoic acid under thermal condition

Abstract

An efficient and practical synthesis of 1,3,5-trisubstituted 2-pyrazoline structures was achieved through cyclization of phenylhydrazine with α,β--unsaturated ketones (chalcones) using methanoic acid (formic acid) as catalyst under thermal condition.

One-Pot Synthesis of Isobenzofuran-1(3h)-Ones Using Sulfuric Acid Immobilized on Silica Under Solvent-Free Conditions and Survey of Third-Order Nonlinear Optical Properties

“…In continuation of our research to develop new and eco-friendly synthetic methodologies [36][37][38][39][40][41][42][43][44][45][46] , we herein present efficient and environmentally benign protocols for the synthesis of isobenzofuran-1(3H)-one derivatives by condensation of phthalaldehydic acid (2-carboxy benzaldehyde) with aryl ketones or 1,3-dicarbonyl compounds catalyzed by H 2 SO 4 -SiO 2 under solventfree conditions at 120 0 C (Scheme 1). To further explore the scope of this protocol, we decided to investigate the condensation reaction of phthalaldehydic acid (2-carboxy benzaldehyde) with another aryl ketones or 1,3-dicarbonyl compounds (Table 2).…”

“…H 2 SO 4 -SiO 2 was prepared according to literature [42]. IR spectra were recorded on a Shimadzu 435-U-04 spectrophotometer (KBr pellets).…”

Aromatization of 1,3,5-Trisubstituted of 4,5-Dihydro-1H-Pyrazoles by In-Situ Generation of I+from Hydrogen Peroxide/Acids/Iodide Potassium or Sodium Systems

“…[45][46][47][48][49][50][51][52][53][54][55] The salient catalytic activities attributed to silica sulfuric acid have encouraged us, in the second part of the present paper, to use various solvents like CH 3 CN, MeOH, H 2 O, EtOH, EtOAc, CH 2 Cl 2 and CCl 4 used for aromatization of 1,3,5-triphenyl-2-pyrazolines (1a) as model reaction, EtOH:H 2 O (10:1, v/v) was the solvent of choice as best results in terms of the yield was obtained using SSA (0.02 g), H 2 O 2 (1 mL) and KI (0.016 g) for 1 mmol of 1,3,5-triphenyl-2-pyrazolines when the reaction was run at 80 o C for 15 min in 90% yield (Table 3). Similarly, to illustrate the scope and usefulness of this methodology, a number of reactions were conducted (Scheme Literature data.…”

“…9 The most important methodology for synthesis of pyrazoles is oxidative aromatization of 1,3,5-trisubstituted-2-pyrazoline 10,11 to their corresponding pyrazole.…”

Chalcones as Versatile Synthons for the Synthesis of 5- and 6-membered Nitrogen Heterocycles

“…Under these conditions, a large variety of substituents can be found in the synthesis of functionalized 2-pyrazolines such as benzodioxane [211], benzofuran [118,212,213], coumarin [214], indenoquinoxaline [215], naphthalene [125], quinoline [216,217], 1,3-thiazole [218] and thiophene [219][220][221]. The introduction of bases such as pyridine [122,[222][223][224], piperidine [129,225,226], triethylamine [227,228], KOH [107], NaOH [229][230][231][232][233][234][235][236][237][238][239][240][241] and NaOAc [242] or acids as formic [243,244], acetic [82,108,116,131,208,243,[245][246]…”