Dithioacetals oxidation

Dithioacetal monoxide anions react with carbonyl compounds in a similar way affording the corresponding a-hydroxy aldehyde dithioacetal oxides 428. Ogura and Tsuchihashi, who performed this reaction for the first time using the anion of methyl methylthiomethyl sulphoxide 324, obtained in this way a series of a-hydroxyaldehydes 429504 (equation 257). 

A general way to achieve thiophilic addition is to use sulfines [149]. The sulfur atom of thiocarbonyl oxides is selectively attacked by carbanions. We have applied this property to aliphatic dithioester oxides and shown [150] that, despite the probably high acidity of the a-protons, thiophilic addition of alkyllithiums is observed, leading to stabilised carbanions. After treatment with electrophiles, dithioacetal oxides were obtained. From a synthetic point of view, it is worthy of note that these adducts are much more easily... 

Cycloaddition reactions of thioaldehydes and sulfines are most probably encountered in plants, as elegantly and soundly shown by the group of Eric Block during their investigation of sulfur products occurring in the Allium species (for a review see [91]). They were able [92, 93] to isolate bicyclic dithioacetal oxides, called zwiebelanes, and also to synthesise them from a thioxosulfine, already described in this review (Sect. 2.6, Scheme 18). An extremely rich stereochemical and analytical study has resulted. 

---