Synthesis of N-acyl-N'-arylurea derivatives

Abstract

To study the syntheticroute of N-acyl-N'-arylurea derivatives which wereexpected to possess anticonvulsant activity. These compounds can be obtained through 2pathways. The first pathway is the isothiocyanatepathway by reacting 2-propylpentanoyl chloride withpotassium thiocyanate in dry acetone to form theisothiocyanate, then aniline or arylamine derivatives wasallowed to react in order to obtain the corresponding N-acyl-N'-arylthiourea with the moderately high yield. Thethiourea derivatives were easily converted to theircorresponding urea by oxidation of its thio carbonylgroup with alkaline hydrogen peroxide. Eight compoundsin either ureide or thioureide type were prepared bythis pathway namelyN-(2-propylpentanoyl)-N'-phenylthiourea,N-(2-propylpentanoyl)-N'-(4-methylphenyl)thiourea,N-(2-propylpentanoyl)-N'-(2-methylphenyl)thiourea,N(2-propylpentanoyl)-N'-(2-nitrophenyl)thiourea,N-(2-propylentanoyl)- N'phenylurea,N-(2-propylpentanoyl)-N'-(4-methylphenyl)urea, N-(2propylpentanoyl)-N'-(2-methylphenyl)urea andN-(2-propylpentanoyl)-N'-(4-nitrophenyl)lurea. The second pathway is the isocyanate pathway byreacting 2-propylpentanoyl chloride with potassiumcyanate in dry dioxane , using stannic chloride ascatalyst , to form the isocyanate in which4-aminopyridine was allowed to react to obtain theproduct. With this method,N-(2-propylpentanoyl)-N'-(4-pyridinyl)urea, which cannot be synthesized by the first pathway, has beensuccessfully prepared with 30 % yield. The chemical structure of the synthesizedcompound were confirmed by Infrared Spectrometry, ('1)Hand ('13)C Nuclear Magnetic Resonance Spectrometry,Mass Spectrometsry, and Elemental Analysis technique.