13C nuclear magnetic resonance of organophosphorus compounds: dihedral dependence of the 2JPCC spin coupling in four-membered cyclic phosphines
Abstract
The α-methyl 2JPCC in 2,2,3,4,4-pentamethylphosphetans is stereospecific with respect to the exocyclic phosphorus substituent; the coupling is large (27–37 Hz) when trans and small (0–5 Hz) when cis to the exocyclic phosphorus substituent.