A Facile synthesis of 1, 2-disubstituted 4-arylmethylene- 2-imidazolin-5-ones via 2-substituted 2-oxazolin-5-ones

In view to synthesize some bioactive 1,2-Disubstituted 4-arylmethylene-2-imidazoline-5-ones (6) through a disciplined route, a modified eco-friendly method has been designed, because 2-imidazolin-5-one derivatives are reported to have a wide range of pharmacological profile. 2-Substituted 2-oxazolin-5-ones (2) which are also known as saturated azlactones and are unstable,were generated in situ fromα-N-acylglycines (1) using p-toluenesulphonyl chloride or tosyl chloride as cyclizing agent in dry benzene in presence of triethylamine base at room temperature. Subsequent addition of aromatic aldehydes (3) and refluxing the mixture for 10 minutes, 2-Substituted 4-arylmethylene-2-oxazolin-5-ones (4) were obtained, which are also known as unsaturated azlactones and are stable. On aminolysis of 2-Substituted 4-arylmethylene-2-oxazolin-5-ones (4) in acidic medium say in glacial acetic acid by primary amines N-Substituted 2-acylamino-2-alkenamides (5) were obtained within 5-10 minutes. The reaction seems to proceed by the cleavage of 1,5-bond of 2-Substituted 4-arylmethylene-2-oxazolin-5-ones (4) by the nucleophiles i.e. primary amines. On continuous heating for 4.0 hours in the presence of catalytic amount of sodium acetate, 1,2-Disubstituted 4-arylmethylene-2-imidazoline-5-ones (6) were the product. There are four steps in total for the conversion of α-N-acylglycines (1) to 1,2-Disubstituted 4-arylmethylene-2-imidazoline-5-ones (6). In this present investigation, all the steps can be carried out in one flask by designing a facile modified route.