P(V) trigonal bipyramidal phosphoranes as model compounds for the description of cAMP‐catalyzed reactions

Abstract 13C NMR low‐temperature investigations have revealed that the dioxaphosphorinane ring, trans‐annelated with a cyclopentane ring (3), prefers an equatorial‐apical alignment in trigonal bipyramidal phosphoranes. However, the 13C NMR low‐temperature investigations of the model compound, in which the dioxaphosphorinane ring is trans‐annelated with a tetrahydrofuran ring (4), have shown that the ligand exchange (pseudorotation) in this compound is very fast on the NMR time scale, even at low temperatures. These results are in fairly good agreement with quantum‐chemical calculations.