Cyclic oxyphosphoranes with six-and seven-membered rings

Abstract

X-ray and variable temperature NMR investigations of cyclic pentaoxyphosphoranes reveal a preference of six-and seven-membered rings for apical-equatorial orientations of trigonal bipyramids. Saturated six-membered rings prefer a boat conformation. Apical-equatorial ring pseudorotations are more facile for five-membered rings, whereas ligand exchange via diequatorial ring placement is more facile for the larger rings. Application to enzymatic reactions of cyclic AMP is emphasized. © 1990, Taylor & Francis Group, LLC. All rights reserved.