P-N compounds. 25. Phosphaminimides. 1. Synthesis and bioevaluation of a derivative of tetrahydro-2H-1,3,4,2-oxadiazaphosphorinium inner salt

2-Phenoxy-4,4-dimethyltetrahydro-2H-1,3,4,2-oxadiazaphosphorinium 2-oxide inner salt, the first known cyclic phosphaminimide, was synthesized by dehydroiodination of its hydrazinium salt. The corresponding 2-phenyl derivative was unstable and not isolated. The 2-phenoxy and 2-phenylphosphorinium iodides and their precursors produced weak inhibition of sympathetic ganglionic transmission. The phosphaminimide caused a slight potentiation and was also found to be less toxic than its corresponding hydrazinium iodide precusor.