Synthesis of (Silylamino)Phospholenes and their Derivatives: Synthesis of a New Spirocyclic Phosphazene

Phospholenes containing one or two methyl groups at the 3 and 4 positions on the heterocyclic ring and bis(trimethylsilyl)amino groups on phosphorus were prepared by treating 1-bromo or 1-chlorophospholenes with lithium bis(trimethylsilyl)amide. Several P(V) derivatives of these 2-and 3-phospholenes were prepared by oxidation with hexachloroethane. The chloro groups in the resulting P-chloro-N-trimethylsilyl derivatives were subsequently replaced by phenoxy groups to afford P-phenoxy-N-trimethylsilyl substituted ring compounds. The P-phenoxy-N-trimethylsilyl derivative was hydrolyzed to the corresponding P-amino phosphine oxide; treated with trifluoroethanol to form a new trispirocyclic phosphazene; and copolymerized with Me₂P(OPh) = NSiMe₃ to give a new phosphazene copolymer containing the phospholene ring (M_w = 3.8 × 10⁴ Da). These new compounds were characterized by ¹H, ¹³C, and ³¹P NMR spectroscopy. The spirocyclic phosphazene was also characterized by X-ray crystallography.