Synthesis of 2,8-dioxaspiro[4.5]decane-1,3,7,9-tetron and the reactions with amines

For the studies of highly-sophisticated utilization of itaconic anhydride, some compounds of polybasic carboxylic acids having a quaternary or a spiro carbon atom were prepared, starting from itaconic anhydride and isoprene. Aliphatic tetracarboxylic dianhydride having a spiro carbon atom with five- and six-membered rings, 2,8-dioxaspiro[4.5]decane-1,3, 7,9-tetrone (TCDA), was also obtained. The reaction of TCDA with primary amines and subsequent dehydration gave two types of products, either diimides or imide (with fiv e-membered ring)-anhydrides (with six-membered ring), depending on the hydr ocarbon moiety of the amines used. It was suggested that each imide-anhydri de was formed by the intramolecular ring transformation of the intermediate amic acid-anhydnide.