Mn(<scp>III</scp>)‐Based Oxidation of (Methylene)Bis(Cyclodiamide)s. Facile Synthesis of Tetraazadispiro‐(Undecanone)s and ‐(Tridecanone)s

ABSTRACT The oxidation of 5,5′‐(methylene)bis(6‐hydroxy‐1,3‐dimethylpyrimidine‐2,4(1 H ,3 H )‐dione) monopiperidinium salts with Mn(OAc) 3 •2H 2 O was carried out in boiling MeCN, producing 2,4,9,11‐tetramethyl‐2,4,9,11‐tetraazadispiro[5.0.5 7 .1 6 ]tridecane‐1,3,5,8,10,12‐hexaones in high yields. A similar reaction using 4,4′‐(methylene)bis(1,2‐diphenylpyrazolidine‐3,5‐dione)s gave 2,3,8,9‐tetraphenyl‐2,3,8,9‐tetraazadispiro[4.0.4 6 .1 5 ]undecane‐1,4,7,10‐tetraones in good yields. The structure determination and the reaction mechanism for the formation of the unique tetraazadispiro(cyclopropane)s are discussed.