Abstract: The classical Erlenmeyer Azlactone Synthesis is one of the most common reaction to yield Azlactones or 5(4H)- Oxazolones or 2-Oxazolin-5-ones. The method involves cyclodehydration followed by condensation of different aromatic aldehydes with hippuric acid in the presence of acetic anhydride as a cyclising agent and anhydrous sodium acetate as a base in homogeneous phase. The method generally evolves a mixture of geometrical isomers of E- and Z- unsaturated azlactones. Azlactones are of the main topic of interest for the medicinal chemists as they show a number of pharmacological activities. Several procedures are developed time to time to produce varieties of unsaturated azlactones with methodological clarity and yield efficiency. In the present investigation, a disciplined route for the synthesis of Z-isomers of 4-Arylmethylene-2-phenyl-2-oxazolin-5-ones are developed using Tosyl chloride (p-Toluene sulphonyl chloride) as cyclocondensing agent. The conversion of α-N-Benzoyl glycine i.e. Hippuric acid (1) to unstable 2-phenyl-2-oxazolin-5-one (2) i.e. saturated azlactone was carried out in dry benzene using tosyl chloride as cyclizing agent in the presence of triethylamine base at room temperature. Then the resultant 2-phenyl-2-oxazolin-5-one (2) is allowed to condense with arylaldehydes (3) by refluxing the content for 10 minutes. The insoluble triethylamine salts were filtered off under suction and washed twice with dry benzene. The filtrate and washings were combined and the solvent was removed under reduced pressure. On trituration of the residue with chilled ethanol, a yellow solid was obtained which was 4-Arylmethylene-2-phenyl-2-oxazolin-5-ones (4) in very appreciable to good yield. All the required steps were carried out in one flask.

Keywords: Saturated azlactone, Unsaturated azlactone, Z-isomer, 4-Arylmethylene-2-phenyl-2-oxazolin-5-ones, 4-(4-Methylphenyl) methylene-2-phenyl-2-oxazolin-5-one, 4-(4-Flurophenyl) methylene-2-phenyl-2-oxazolin-5-one, Disciplined route

PDF | DOI: 10.17148/IARJSET.2023.10656

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