Priyanka Borah - Academia.edu (original) (raw)
Uploads
Papers by Priyanka Borah
IARJSET, 2021
The classical Erlenmeyer Azlactone Synthesis is one of the most common reactions to produce Azlac... more 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.
IARJSET, 2021
The classical Erlenmeyer Azlactone Synthesis is one of the most common reactions to produce Azlac... more 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.