= Solution
\b[Secondary amines normally favor non-geminal disubstitution], putting the second amino substituent on a different phosphorus. The first installed $\mathrm{NR_2}$ group donates <electron> density to the P–N framework and deactivates its own phosphorus toward further attack. It is also bulkier than an initially installed primary-amino group. Crucially, $\mathrm{P{-}NR_2}$ has no N–H <proton>, so the proton-abstraction/chloride-elimination pathway that can direct a primary amine geminally is unavailable. Direct attack at a less-deactivated $\mathrm{PCl_2}$ site is favored. The resulting non-geminal products can have cis or trans relative orientations around the ring; <non-geminal substitution> alone does not select one of these <stereoisomers>. These are useful trends, with known substituent-dependent exceptions in experimentally characterized mixed derivatives.<Regiochemical Control in the Substitution Reactions of Cyclotriphosphazene Derivatives with Secondary Amines by Serap Beşli and others>[2018, abstract, pyrrolidine/dimethylamine substitution of differently substituted rings]{ref}
Back to article page
