Determination of stereochemistry of vinyl phosphates from proton nuclear magnetic resonance chemical shifts
Abstract
Studies of a wide range of structures R1R2P(X)·O·CYCHW (Y = H, Me, or Ph) indicate that in any pair of isomers the proton cis to the phosphoryl group resonates to low field of the corresponding trans-proton. Reinterpretation of published data suggests that boron trifluoride–ether complex causes a preferential deshielding of the proton trans to the phosphoryl group in such compounds. In the absence of knowledge of the signs of the coupling constants. JPH values cannot be used to determine stereochemistry.