Various menthyl-containing phosphinothioates were prepared. Using these compounds, an unusual phosphorus-promoted cleavage of the C–S bond with lithium-naphthalene was examined. The C–S/P–S cleavages could be controlled by the amount of naphthalene and temperature applied. Also, the P–S cleavage was confirmed to retain the configuration about the P and this feature was used for achieving a stereospecific formation of the C–P bond.