Dithienium Tetrafluoroborate

Solubility soluble in CH2CI2-CH3NO2 mixtures and CH3CN. Analysis of Reagent Purity NMR (CD3NO2) 5 11.10 (s, IH), 

l Preparative Methods can be prepared by reaction of 1,3-dithiane with trityl tetrafluoroborate in dry CH2CI2 at reflux (30 min), followed by solvent evaporation, trituration of the residue with cold Et20, collection of the solid by filtration, and drying in vacuo (92%). 

Handling, Storage, and Precaution store at —20°C under moisture-free conditions (where it is stable for several 

AllylsUanes are reactive towards 1,3-dithienium tetrafluoroborate. The intermediate -silyl carbocation typically suffers elimination of the silyl cation to furnish a 2-allyl-1,3-dithiane (eq 5). This protocol was employed to homologate allylsilane 3 to produce dithiane 4, an intermediate in the synthesis of epiantillatoxin (eq 6). A fert-butyldimethylsilyl ether used as a protecting group was cleaved from 3 during this reaction. 

3-Dithienium tetrafluoroborate has been shown to react with a n allylzirconium complex to give an aUyldithiane (eq 7). The reagent has also been used as an electrophUe to introduce a carbon substituent into the para position of an activated benzene nucleus (eq 8).  

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The alkylation of O-silylated dienolates with 1,3-dithienium tetrafluoroborate shows useful y-selectivity [equation (59)]. The y-alkylated products are selectively protected 1,5-dicarbonyl compounds. Unsaturated 1,5-diketones, precursors of various heterocycles, can be prepared by the reaction of the potassium enolates of methyl ketones with acyl keten dithioacetals [equation (60)]. ... 

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