Mercury alkyls sulphide

Diethyl methylthiomethylphosphonate can be alkylated by successive treatment with n-butyl-lithium and an alkyl iodide the lithio-derivatives of such alkylated esters react with carbonyl compounds to give /S-alkoxyphosphonate adducts. These products decompose readily to vinyl methyl sulphides, which undergo mercury(ii)-promoted hydrolysis to the corresponding ketone. These transformations are outlined in Scheme 53. 

Corey has reported a novel method for the introduction of two alkyl appendages at the carbonyl carbon of ketones. Ketones react with the anion of diethyl allylthiomethylphosphonate (155) to give vinyl allyl sulphides such as (156) heating in the presence of mercury(ii) oxide induces a thio-Claisen rearrangement to yield the aldehyde (157), which can be further elaborated by various oxidation-reduction sequences to give, for example, the spiro-enone (158). 

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