An NMR study of sequential intermediates and collateral products in the conversion of 1,3,6,8-tetraazatricyclo[4.4.1.13,8]dodecane (TATD) to 1,3,6,8-tetraazatricyclo[4.3.1.13,8]undecane (TATU)

In situ 1H nuclear magnetic resonance spectroscopy was used to investigate the processes that occur during the synthesis of 1,3,6,8-tetraazatricyclo[4.3.1.13,8]undecane (TATU). NMR analysis showed a reaction mixture containing more than one compound. The production of these intermediates and collateral products was rationally supported by a careful 1H NMR monitoring study. We characterized 1,3,5-triazabicyclo[3.2.1]octane (TABO, 4) and 3-(2-aminoethyl)-1,3,5-triazabicyclo[3.2.1]octane (AETABO, 7) by 1H and 13C NMR in D2O solution inside the NMR sample tube, as an intermediate and collateral product of the reaction, respectively. Further, a reaction of 1,3,6,8-tetraazatricyclo[4.4.1.13,8]dodecane (TATD) with 15N-labeled ammonium chloride was carried out. The 15N NMR and GC-MS experiments indicated that 15N was incorporated into TATU, TABO, and urotropine.