Abstract: Phenyl isothiocyanate is a stable compound and can be used as a potential cyclizing agent. It is used as synthon due to their diverse reactions in synthetic organic chemistry. In comparison to isocyanates (-N=C=O), their sulphur analogues, isothiocyanates (-N=C=S) are less toxic and to some extent less hazardous. Though isocyanates are comparatively more reactive but the use of isocyanates is drastically limited by the researchers after December 3, 1984 which is the date of Bhopal disaster held in Union Carbide Factory, Bhopal, Madhya Pradesh (India) due to the leakage of Methyl isocyanate (MIC) where thousands of people were died due to the toxic exposure of MIC (Me-N=C=O). In the present investigation, a mixture of α-N-acetylglycine (1), phenyl isothiocyanate (2) and aromatic aldehydes (3) in a molar ratio of 1:1.2:2 respectively with pyridine as a catalyst was thoroughly mixed and was heated in oil bath for 30 minutes at 160o-170oC in an open vessel under solvent free condition. On work-up, the products obtained were 4-Arylidene-1-phenyl-2-substituted styryl-2-imidazolin-5-ones (4). The reaction seems to proceed with the cyclization of α-N-Acetylglycine (1) by phenyl isothiocyanate (2) to produce 2-Methyl-2-oxazolin-5-one and arylideneimine (6) which condenses with methylene at 4-position of 2-Methyl-2-oxazolin-5-one and leads to the formation of 4-Arylidene -2-methyl-2-oxazolin-5ones (5) with the extrusion of aniline moiety. Another mole of aldehyde (3) condenses with aniline and forms second mole of arylideneimine which attacks at the active methyl group available at 2-position of oxazolones(5)forming 4-Arylidene-2-substituted styryl-2-oxazolin-5-ones(7). The subsequent anilinolysis of 1,5-bond of 4-Arylidene-2-substituted styryl-2-oxazolin-5-ones (7)and followed bycyclodehydration produces the targeted product 4-arylidene-1-phenyl-2-substituted styryl-2-imidazolin-5-ones (4). These compounds were assessed in vitro for anti-microbial activity.
Keywords: Phenyl isothiocyanate, Synthon, α-N-acetylglycine, 4-Arylidene-1-phenyl-2-substituted styryl-2-imidazolin -5-ones, Anti-microbial activity
| DOI: 10.17148/IARJSET.2019.6609