A microwave-catalyzed rapid, efficient and ecofriendly synthesis of substituted pyrazol-5-ones (Short communication)

Abstract

A series of 1-(3,4-dihydro-3-oxo-2H-1,4-benzoxazine-2-carbonyl)-3-methyl-4-(substituted phenylhydrazono)-2-pyrazolin-5-ones have been synthesized by the reaction of 2H-3,4-dihydro-3-oxo-1,4-benzoxazine-2-carboxylic acid hydrazide with substituted acetoacetic ester derivatives using acetic acid as solvent under microwave irradiation (MWI), as well as by conventional methods. The reaction rate is enhanced tremendously and the yields are improved under MWI as compared to conventional methods.

Benign Approaches for the Microwave‐assisted Synthesis of Five‐membered 1,2‐N,N‐heterocycles

“…Furthermore, compound benzoxazine ( 179 ) undergoes a nucleophilic addition reaction with hydrazine hydrate in the presence of methanol under MWI to yield 2 H ‐3,4‐dihydro‐3‐oxo‐1,4‐benzoxazine‐2‐carboxylic acid hydrazide ( 180 ). The diazonium salt of a primary amine ( 174 ) when coupled with an acetoacetic ester ( 175 ) at 0–5°C in the presence of sodium acetate gives substituted acetoacetic ester derivatives ( 176 ) (Scheme ) .…”

“…Furthermore, compound benzoxazine (179) undergoes a nucleophilic addition reaction with hydrazine hydrate in the presence of methanol under MWI to yield 2H-3,4-dihydro-3-oxo-1,4-benzoxazine-2-carboxylic acid hydrazide (180). The diazonium salt of a primary amine (174) when coupled with an acetoacetic ester (175) at 0-5°Cin the presence of sodium acetate gives substituted acetoacetic ester derivatives (176) (Scheme 47, 48)[91].A series of 1-(4-substitutedphenyl)-3-phenyl-1Hpyrazole-4-carbaldehyde (185) has been synthesized and tested for their anti-inflammatory and analgesic activities. Formation of the pyrazole derivatives was achieved by treating Vilsmeier-Haack reagent.…”

A Facile and Rapid Method for Preparation of Thiazine and Thiadiazine Derivatives by Sonication Technique

“…21 Fused s-triazoles and their derivatives have been investigated for their potential pharmacological properties such as antifungal, 22 antidepressant, 23 and plant growth regulators. 24 Our research group has a longstanding interest in the synthesis of heterocyclic compounds by newer methods such as microwave [25][26][27][28] and sonication [29][30][31] aiming to develop more rapid and advantageous construction of libraries of small heterocyclic compounds. As a result we have recently reported the synthesis of benzothiazipine, thiophene, triazole, thiadiazole, and spiro oxadiazole, and also their biological studies.…”

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

“…[1][2][3][4][5] The discovery of this class of compounds provides an outstanding case history of modern drug development and also emphasizes the unpredictability of biological activity from structural modification of a prototype drug molecule. [13][14][15] After the pioneering work of Fischer and Knoevenagel in the 19 th century, the reaction of α,β-unsaturated aldehydes and ketones with phenylhydrazine in acetic acid under reflux became one of the most popular methods for the preparation of 2-pyrazolines. 12 Thus, the synthesis of the 1,3,5-trisubstituted 2-pyrazolines moiety is always a great challenge.…”