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

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-tetrahydropyrimido2,1-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, dibenzoc,l]-1,6,10,15-tetraazacyclooctadecane-5,11,16,22-tetraone (IX). Reaction of 1,3-propanediamine with phthaloyl chloride gave 6,13-propanodibenzc,h]-1,6-diazecine-5,7,12,14-tetrone (XII). Spectroscopic data of the heterocycles obtained and chemical properties of II are given.