Heterocycles derived from the condensation of 1,3‐propanediamine with phthalic acid derivatives

Abstract

Abstract The condensation of phthalic anhydride with 1,3‐propanediamine afforded N ‐( o ‐carboxybenzoyl)‐1,3‐propanediamine (I) which by intravolecular cyclization was transformed into 2,3,4,6‐b‐tetrahydropyrimido[2,1‐ a ]isoindol‐6‐one (II) rather than the benzodiazonine (III). An intermediate in the condensation is proposed. The reaction of 1,3‐propanediamine with dimethyl phthalate also did not afford III, but rather a more complex product, dibenzo[ c,l ]‐1,6,10,15‐tetraazacyclooctadecane‐5,11,16,22‐tetraone (IX). Reaction of 1,3‐propanediamine with phthaloyl chloride gave 6,13‐propanodibenz[ c,h ]‐1,6‐diazecine‐5,7,12,14‐tetrone (XII). Spectroscopic data of the heterocycles obtained and chemical properties of II are given.