Figure 5. Gibbs free-energy profile for the substitution reaction between the second FOX-7 and CHZ
There are two reactive sites on the FOX-7 molecule that can be substituted by CHZ. Therefore, it is necessary to verify why the pathway of bisamino substitution into the ring is difficult to proceed. In Scheme 4, after an amino group on FOX-7 is substituted by CHZ, another amino group is also substituted by CHZ, and finally a six-membered ring structure is formed.