The tert-butyllithium metallation of compounds containing the group Pv—CH2—CH2—SR proceeds by elimination of the group SR (R = H, CH3) followed by addition of tert-BuLi. Application of this addition–elimination reaction to functionalized phosphine-oxides [Formula: see text] leads to the synthesis of γ-diphosphorylated compounds. These dissociate in basic medium following a mechanism which is the reverse of their formation as shown by treatment of the reaction mixture with p-chlorobenzaldehyde to give ethyl p-chlorocinnamate.
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