Abstract: The classical Erlenmeyer Azlactone Synthesis is one of the most common reactions to produce Azlactones or 5(4H)-Oxazolones. The process consists of cyclodehydration- condensation of different arylaldehydes with hippuric acid in acetic anhydride in the presence of anhydrous sodium acetate as a homogeneous base catalyst. The procedure generally produces a mixture of geometrical isomers of E and Z. In the present investigation, a disciplined route for the synthesis of either E or Z-isomer is developed. The conversion of α-N-Benzoyl glycine i.e. Hippuric acid (1) to unstable 2-phenyl-2-oxazolin-5-one (2) was carried out in dry benzene using either ethyl chloroformate or benzene sulphonyl chloride or p-toluene sulphonyl chloride as cyclizing agent in the presence of triethylamine base at room temperature. Then the condensation of cinnamaldehyde with 2 is carried out by refluxing the content for 10 minutes. The solvent was removed under reduced pressure. The unsaturated azlactone obtained, (E)-4-cinnamylidene-2-phenyl-2-oxazolin-5-one (3) can be isolated by triturating it with ethanol or may be subjected to solvolysis directly. Hydrolysis, alcoholysis and aminolysis of (E)-4-cinnamylidene-2-phenyl-2-oxazolin-5-one (3) leads to the formation of corresponding dehydroamino acid (4), esters of dehydroamino acid (5) and alkenamide (6) respectively by the cleavage of 1,5- bond of the azlactone (3) with (E)-configuration maintaining the steric integrity at 4-position of (E)-azlactone. (E)-azlactone (3) can be converted to (Z)-azlactone (7) by boiling it in dry pyridine for 15 minutes. Similar way, the solvolysis of 1, 5-bond of (Z)-isomer of 4-cinnamylidene-2-phenyl-2-oxazolin-5-one (7) affords the solvolysis products with (Z)-configuration. For each of the product formation, all the required steps are carried out in the same flask.

Keywords: Geometric isomers, 4-Cinnamylidene-2-phenyl-2-oxazolin-5-one, Stereospecific, Solvolysis, Disciplined route.

| DOI: 10.17148/IARJSET.2021.8655