Bis methylthio methylphosphonate

Dehydration of Aldoximes. A range of alkyl, aryl, and heteroaryl aldoximes undergo smooth dehydration with4-(dhnethyl-amino)pyridinium chlorosulfite chloride at —10 to +10 °C to give the corresponding nitriles in 70-100% yield (eq 3).  

Alternate Name O, O-dimethyl formylphosphonate 5,5-dimethyl thioacetal. 

Preparative Methods (MeO)2P(0)CH(SMe)2 and related 5,5-thioacetals of formylphosphonates are readily prepared in high yields by the Arbuzov reaction of trialkyl phosphites with chloro dithioacetals (eq 1). Other syntheses of thiophospho-nates are known.  

Reactions with Aldehydes and Ketones. The carbanion derived from the treatment of (Me0)2P(0)CH(SMe)2 with a base reacts with cyclic and acyclic, aliphatic and aromatic aldehydes and ketones in a Horner—Wadsworth—Emmons reaction to give ketene 5,5-thioacetals in high yields (eq 2 ). The carbanion is generated using either butyllithium in THE at —78 °C or, less commonly, sodium hydride in DME. Alternatively, with aromatic aldehydes the reaction may be performed under two-phase conditions using benzyltriethylammonium chloride (TEBA) as a phase-transfer catalyst.  

Ketene 5,5-thioacetals are key synthetic intermediates, susceptible to nucleophilic and electrophilic attack. Hydrolysis and alcoholysis of ketene 5,5-thioacetals yields carboxylic acids and esters, respectively. Other transformations of ketene 5,5-thioacetals allow homologation of the precursor carbonyl compound and polyfunctional ketene 5,5-thioacetals provide access to heterocycles (e.g. eq 3).  

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