Carbon‐13 n.m.r. study of 31P13C spin–spin coupling constants in dichloro‐ and monochloro‐vinyl phosphate derivatives

Abstract

AbstractCarbon‐13 chemical shifts and J(PC) coupling constants of 29 vinyl phosphate derivatives are presented. In the series of compounds (R1O)2P(O)OC1(R)C2X2 (where 3 in R indicates the first carbon of the R2 substituent) large differences were found between the 3J(P, O, C‐1, C‐3) and 3J(P, O, C‐1, C‐2) coupling constants of the chlorinated (XCI) and the unsubstituted (XH) derivatives. A possible explanation of this phenomenon is given on the basis of Jameson's s bond character theory. Strong stereospecificity of 3J(P, O, C‐1, C‐3) coupling constants was observed in the series of compounds (R1O)2 P(O)OC1(R)C2HR3. Coupling constants varied between 3.2–4.9 Hz in the E isomers, while peaks could not be resolved in the Z isomers. The 3J(P, O, C‐1, C‐2) coupling constants were regularly 20–30% greater in the Z than in the E isomers.