An unusual product obtained from condensation between ethylenediamine and formaldehyde in basic medium

Reaction between ethylenediamine and formaldehyde normally affords 1,3,6,8-tetraazatricyclo[4.4.1.13.8]dodecane (TATD) but in this case also afforded 3,3′-ethane-1,2-diyl-bis-1,3,5-triazabicyclo[3.2.1]octane (ETABOC), this being an unusual product from such condensation.