31P Chemical Shifts and 31P-13C Coupling Effects in the Stereochemical Analysis of Benzo-7-phosphanorbornene Derivatives

Article abstract of DOI:10.1002/mrc.1260231110

The first phosphines based on the benzo-7-phosphanorbornene system have been prepared and found to have extremely deshielded 31P nuclei.The phosphine with a P-tert-butyl group gives the most downfield value (δ +152.5) ever recorded for a tertiary phosphine.The lone-pair orientation in phosphines controls the magnitude of ²J (PC) and ³J (PC), and these effects were used to determine stereochemical features of the phosphines.These compounds were formed by HSiCl3-pyridine reduction of the Diels-Alder adducts of isophosphindole oxides with norbornadiene. 13C NMR was also used to confirm the assignment of these phosphine oxides.