Use of sulfides and dithioacetals

Boekelheide and his collaborators [407] have described a two-step sequence for transforming sulfide linkages to carbon-carbon double bonds — Stevens rearrangement of sulfur ylides and Hofmann elimination — which they found particularly useful for the synthesis of cyclophane derivatives, such as the [2.2]metaparacyclophane- 1,9-diene shown. The Ramberg-Backlund rearrangement (see Section 4.3.2) was unsatisfactory for such highly strained molecules. 

As mentioned in Section 4.2.2.6, dithioacetals can be used in coupling reactions with Grignard reagents in sequences leading to the formation of carbon-carbon single and double bonds. The metal-catalysed reactions depicted here exemplify their uses for olefination reactions, which opened the way to many useful synthetic applications [319]. 

The desulfurdimerization reaction of dithioacetals proceeds via a thioketone intermediate. 

Indeed, metal carbonyls were also reported to react with thioketones to yield dimeric olelins [31V, 409]. 

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