Abstract: The objective of the present investigation was to develop a method for a fast and facile synthesis of 4-(Heteroaryl)methylene-2-phenyl-2-oxazolin-5-ones (4) and their corresponding dehydroamino acids (5), their ethyl and methyl esters (6, 7) and anilides (8) by solvolysis and aminolysis through 1,5-bond cleavage of 2-oxazolin- 5-ones (4) which are used as synthons.

An alternative modification for the fast and convenient synthesis of 4-(Heteroaryl)methylene-2-phenyl-2-oxazolin - 5-ones (4) where heteroaryl groups are furan (4a), pyrrole (4b) and thiophene (4c) moieties, is developed. They are the unsaturated azlactones. The conversion of α-N-benzoylglycine or hippuric acid (1) to unstable 2-phenyl-2- oxazolin-5-one (2) was carried out by using cyclising agents namely either Benzene sulphonyl chloride or p-Toluene sulphonyl chloride or Ethyl chloroformate in dry benzene in the presence of triethylamine as base at room temperature, which declined the risk of high temperature as well. After condensation of 2-Formyl heteroarenes namely 2-Formylfuran (3a), 2-Formylpyrrole (3b) and 2-Formylthiophene (3c) with 2-phenyl-2- oxazolin-5-one (2), the solvent was removed under reduced pressure. The removed solvent can be reused. These unsaturated azlactones i.e. 4-(Heteroaryl)methylene-2-phenyl-2-oxazolin-5-ones (4) can be isolated by trituration with chilled ethanol and can also be recrystallised with ethanol. Otherwise, the resultant unsaturated azlactones 4a, 4b and 4c respectively were subjected to hydrolysis, ethanolysis, methanolysis (where ethanolysis and methanolysis  are commonly called alcoholysis) and aminolysis directly in the same flask to obtain 2-Benzoyl amino-3-heteroarylprop-2-enoic acids (i.e. dehydroamino acids) (5), their esters namely Ethyl/ Methyl-2-Benzoylamino-3-heteroarylprop-2-enoates (6, 7) and anilides namely N-Phenyl-2-Benzoylamino-3-heteroarylprop-2-enamides (8) respectively using the view of Green Chemistry methodology.

Keywords: 4-(Heteroaryl)methylene-2-phenyl-2-oxazolin-5-ones, Unsaturated azlactones, Synthons, Solvolysis, Anilinolysis, Green Chemistry.

| DOI: 10.17148/IARJSET.2024.11627