Monatshefte ftir Chemie 128, 675-679 (1997) Monatshefte fiir Chemie Chemical Monthly © Springer-Verlag 1997 Printed in Austria Condensation of 1,3-Diketones with 1,8-Diaminonaphthalene: Synthesis of B is ( 2,3-dih y dro pe rimi dine-2-sp i ro )c y c l oalkan es I. Yavari*, H. Mostafavi, D. Tahmassebi, and R. Hekmat-Shoar Chemistry Department, Tarbiat Modarres University,Tehran, Iran Summary. Cyclic 1,3-diketones like cyclopentane-l,3-dione, cyclohexane-l,3-dione, and 5,5-di- methylcyclohexane-l,3-dione react with 1,8-diaminonaphthalene to afford new condensed hetero- cyclic spiro systems. Keywords. 1,3-Diketones; 1,8-Diaminonaphthalene;2,3-Dihydroperimidine; Spiro compounds. Kondensation von 1,3-Diketonen mit 1,8-Diaminonaphthalin: Synthese yon Bis(2,3-dihydroperimidin-2-spiro)cycloalkanen Zusammenfassung. Cyclische 1,3-Diketone wie Cyclopentan-l,3-dion, Cyclohexan-l,3-dion und 5,5-Dimethylcyclohexan-l,3-dion reagieren mit 1,8-Diaminonaphthalin zu neuen kondensierten heterocyclischen Spiranen. Introduction The synthesis of perimidine based heterocyclic systems by reaction of 1,8- diaminonaphthalene (1) and carbonyl compounds, [1-3] is of considerable importance in view of their utility as dye intermediates and coloring materials for polymers [4]. In addition, they have been reported to possess anti-inflammatory, CNS depressant, anti-bacterial, and anti-fungal activities [5]. Direct heating of 1 and benzyl methyl ketone results in the formation of toluene and 2-methylperimidine (2, [6]). This observation suggests that similar formation of perimidine derivatives should occur from 1,3-diketones such as pentane-2,4- dione (3). The formation of 2 and 2,2-dimethyl-2,3-dihydroperimidine (4) by heating of 1 with 3 prompted us to examine this reaction using cyclic 1,3-diketones such as 5a, 5b, and 5c. We report here a one-pot synthesis of the hitherto unknown bis(2,3-dihydroperimidine-2-spiro)cycloalkanes 6a, 6b, and 6c.