Reactions of carbonyl compounds with tervalent phosphorus reagents. Part IV. Structure of a tetracyclone–dimethyl phosphonate adduct revised by X-ray crystal analysis

Abstract

The structure of the αβ-unsaturated ketone product of the thermal reaction of tetracyclone with dimethyl phosphonate has been determined by X-ray single-crystal analysis. The unit cell is triclinic with a= 12·088 ± 0·005, b= 15·817 ± 0·005, c= 8·914 ± 0·005 Å, α= 82·6 ± 0·1°, β= 119·0 ± 0·1°, γ= 120·9 ± 0·01°; Z= 2, space group P. The structure was solved from diffractometer data by direct methods, and refined by block-diagonal least-squares techniques to R 0·083 for 4828 observed reflections. The adduct is now shown to be a γ-ketophosphonate and steric factors are believed to control its formation.