M. Haemers, R. Ottinger, Daniel Zimmermann
1973
Citations
0
Influential Citations
19
Citations
Journal
Tetrahedron
Abstract
Abstract 13 C and 31 P chemical shift data for eight 2-methoxy-1,3,2-dioxaphosphorinanes are reported. Examination of pairs of geometrical isomers, which differ only in the orientation of the OMe substituent on P III , have shown that both the 31 P and the 13 C signals of C 4,6 atoms appear 3–4 ppm at higher field when the OMe is axial compared with the equatorial isomer. This observation can be associated with the 1–3 syn diaxial interaction between the phosphorus axial substituent and the axial hydrogens on C 4,6 and should thus constitute, in the future, a supplementary tool for the structural analysis of this kind of compound. Important long range δ effects were observed both on 13 C and especially on 31 P chemical shifts. It is suggested that the high field δ e effects could reflect a direct stereoelectronic interaction between the P atom and the cyclic C-5 atom. This interpretation is supported by a study of the 31 P… 13 C coupling constants and their stereochemical dependence.