Theoretical Conformational Analysis of 1,3,2-Benzodioxaphosphinan-4-ones

We previously [1] studied the structure of 1,3,2benzodioxaphosphinan-4-ones by X-ray analysis, by IR spectroscopy, and by measuring their dipole moments. Regardless of the aggregate state, the phosphorus-containing heteroring with planar fragments exists preferentially in a flattened sofa conformation and that the exocyclic substituent occupies axial (N C O, NEt 2 ) or equatorial (Cl) position. In the present work we performed theoretical conformational analysis of 1,3,2-benzodioxaphosphinan-4-ones I IV by nonempirical B3LYP/6-31G(d) quantum-chemical calculations.