2,4,8,10-Tetraoxaspiro5.5undecane-3,9-diylbis(methylene)-bis(3- or 4-aminobenzoates) were obtained by interaction of potassium salts of and aminobenzoic acids with 3,9-dibromomethyl-2,4,8,10-tetraoxaspiro5.5undecane in a molar ratio of 1:2. It was found that they react with a double amount of maleic anhydride to form the corresponding bismaleamides, the intramolecular cyclization of which in the presence of toluenesulfonic acid yielded previously undescribed 2,4,8,10-tetraoxaspiro5.5undecane-3,9-diylbis(methylene)bis(3 or 4-(2,5-dioxo-2,5-dihydro-1-pyrrol-1-yl)benzoates).
O. A Kolyamshin (Wed,) studied this question.