Reactivity of hydroxy and amino derivatives of 2-Phenyl-1H-imidazoline and 2-Phenyl-1H-imidazole toward isocyanates: synthesis of appropriate carbamates and ureas

Abstract

Reactivity of 2-(4-hydroxyphenyl)-1H-imidazoline and 2-(4-hydroxyphenyl)-1H-imidazole toward substituted phenyl isocyanates was studied. When mentioned imidazoline was treated with 2.5 equiv of substituted phenyl isocyanate, three N,O-dicarboxamides were prepared (substituents are H, 4-NO2, and 4-CH3). Subsequently, N,O-diacetylated 2-(4-hydroxyphenyl)-1H-imidazoline was prepared and selective deprotection method was developed for preparation of 1-acetyl-2-(4-hydroxyphenyl)-1H-imidazoline using diethylamine in acetone. Six carbamates derived from this imidazoline were then prepared using 1.1 equiv of substituted phenyl isocyanates (substituents are H, 4-CH3, 4-OCH3, 4-NO2, 4-CN, and 3-CF3). Finally, two carbamates were prepared from 2-(4-hydroxyphenyl)-1H-imidazole (substituents are 4-NO2 and 4-CN). No reactivity to imidazole ring was observed in this case. Eight derivatives were subjected to antimycobacterial screening. Concurrently, reactivity of 2-(2-aminophenyl)- and 2-(2-hydroxyphenyl)-1H-imidazole toward aliphatic and aromatic isocyanates was studied. Eight ureas were prepared using equivalent mixture of 2-(2-aminophenyl)-1H-imidazole and isocyanate (Et, Pr, isoPr, terc-Bu, Cy, Ph, 4-CH3C6H4, 4-CNC6H4). Similar attempts to obtain related carbamates from 2-(2-hydroxyphenyl)-1H-imidazole lead only to three substituted phenyl carbamates (substituents are 4-CH3, 4-NO2, and 4-CN). In both cases, no reactivity to imidazole ring was observed again.