(2R,4R)-4-(2-Eth­oxy-2-oxoeth­yl)-2,6,6-trimeth­yl–2-oxo-1,3,6,2λ⁵-dioxaza­phospho­can-6-ium iodide

The title compound, C₁₁H₂₃NO₅P⁺·I⁻, consists of an eight-membered cationic heterocyclic ring in a boat–chair conformation. The ring features a tetra­alkyl­ammonium N and a methyl­phospho­nate P atom. A –CH₂(CO)OC₂H₅ ester side chain at the C adjacent to oxygen produces two chiral centers at that substituted C atom and the P atom, both of which were determined to have absolute R,R configurations. A previously determined racemic bromide analog has exactly the same ring but with a –C₁₅H₃₁ side chain. In that structure, both chiral centers show the same relative R/S,R/S configurations, but the ring in the bromide analog is in a boat conformation.