Studies of heterocyclic compounds. XVIII. Synthesis of 1-(substitutedphenyl)-2,3-tetramethylenepyrrolo[2,1-b]benzothiazoles.

Abstract

1-(Substituted-phenyl)-2, 3-tetramethylenepyrrolo [2, 1-b] benzothiazoles (IV-2-IV-17) were synthesized from the correspoding 3-(substituted-phenyl) thiazolo [2, 3-b] benzothiazolium perchlorates (III) by the reaction of 1-morpholino-1-cyclohexene, an enamine. On reaction with cuprous cyanide p-substituted bromobenzene (IV-2) furnished benzonitrile (IV-23), which was converted into the corresponding 1-phenyl derivatives (IV) with various aliphatic functional groups at the para position of the phenyl moiety. On reaction with methylmagnesium iodide and subsequent acid hydrolysis IV-23 was converted into acetophenone (IV-24), which reacted with methyltriphenylphosphylene to give 2-phenylpropylene (IV-38). Hydroboration of IV-38 afforded 2-phenylpropanol (IV-39), which was oxidized into the corresponding propionic acid (IV-43), the sulfur atom being oxidized at the same time into sulfoxide. Deoxygenation of the ester (IV-44) was successfully carried out with PBr3 to obtain the desired α-phenyl substituted propionic acid ester (IV-45).