Optically active trivalent phosphorus compounds—I: Diastereoisomeric o-menthyl ethylphenylphosphinites: synthesis,chirality at phosphorus and stereochemistry of nucleophilic displacement reaction

The reaction between racemic ethylphenylchlorophosphine and menthol has been found to give a mixture of diastereoisomeric O-menthyl ethylphenylphosphinites (4) in unequal ratio. The diastereoisomeric content depends mainly on the tertiary amine used for the condensation. The chirality at phosphorus in the diastereoisomeric esters (4a and 4b) has been assigned by means of chemical correlation (conversion into optically active methylethylphenylphosphine oxide) and proton NMR spectra. It has been demonstrated that nucleophilic substitution at phosphorus in 4 occurs with inversion of configuration.