Synthesis, stereochemistry, and molecular and crystal structure of exo-3-phenyl-3-phosphabicyclo[3.2.1]oct-6-ene 3-oxide

Abstract

The syntheses of both the title compound and the endo-3-phenyl isomer are described. The isomer assignments were made on the basis of n.m.r. studies and confirmed by a crystal-structure analysis of the exo-3-phenyl compound. The crystals of C₁₃H₁₅OP are triclinic, space group P, Z= 2, with unit cell dimensions a= 5.973(2), b= 10.496(2), c= 10.699(2)Å, α= 120.27(2), β= 104.12(2), and γ= 77.60(2)°. The structure was solved by the heavy-atom method from diffractometer data and refined to an R value of 0.030. The phosphorinan ring adopts a chair conformation which is substantially flattened at the phosphorus end. The ring conformation, bond lengths, and valence and torsional angles are compared with those in several bicyclic[3.2.1] and monocyclic systems reported in the literature.