Grignard reagents reaction with dithioesters

Organocopper Reagents. When catalytic amounts of copper(I) bromide are used, the reaction of CS2 with Grignard reagents leads to dithioesters in 80-100% yield (eq 3). ... 

The thiophilic addition of aliphatic Grignard reagents to dithioesters deserves some comment. Although they are less reactive than organolithium compounds, their reactions are selective. With enethiolizable dithioesters, enethiolization cannot be avoided with the organolithium species, and at low temperatures this can become exclusive [332]. Enethiolization does not interfere in the case of the less... 

Synthesis of saturated and unsaturated dithioesters through reaction of Grignard reagents with phenylisothiocyanate, alkylation and sulfhydrolysis... 

The reaction of dithioesters with Grignard reagents is even more remarkable. Because sulfur and carbon have about the same electronegativity, the Grignard reagent may add to either end of the ji bond. If it adds to sulfur, the resulting anion is stabilized by two sulfur atoms, rather like the dithiane anions we have seen earlier in this chapter, and can be used as a d1 reagent. 

Syntheses of dithioesters by the reaction of Grignard reagents with dithiochloroformates have been reported, but the yields were at best modest [5] ... 

S-Methylation. The known reaction of Grignard reagents with carbon disulfide and then with methyl iodide has been extended successfully to the more reactive ally lie Grignard reagents la and lb to give dithioesters 2a and 2b. These can be converted to the isoprenic ketene dimethyl dithioacetals 3a and 3b. These... 

Dithioesters. These esters have been prepared by reaction of Grignard reagents with carbon disulfide in THE and then with an alkyl halide. However, yields were low with f-alkylmagnesium halides. The yields are greatly improved by addition of catalytic amounts of copper(I) bromide, and a wider range of Grignard reagents can... 

When certain jS-keto-dithioesters (87) are treated with Grignard reagents, thiophilic addition occurs and 2-hydroxycyclopropanone dithioketals (88) are produced (Scheme 35) Only one isomer is obtained and a concerted cis-homo-l,4-addition has been proposed to account for the stereospecificity observed. Along somewhat similar lines, Giusti and coworkers have synthesized several cyclopropanone ketals by treating l,3-dibromo-2-propanone ketals with active metals (Table 20). Allenes are a byproduct in this reaction. Dihaloketals may also be cyclized electrolytically (Table 21). ... 

If THF is used as solvent, dithioesters can be obtained in 60-85% yield. This method fails when f-alkyl- or cyclohexyl-magnesium halides are used. With diethyl ether as solvent, the dithioesters are obtained in poor yields. The reaction of CS2 with an allylic Grignard reagent followed by methylation affords... 

Transient Species.— Treatment of carbonyl compounds with hydrogen sulphide under pressure in the presence of molybdenum sulphide leads to reduction, and involves the formation of thioketonic intermediates. Aliphatic thioketones and a )8-unsaturated thioketone (27) are proposed as intermediates in the reaction of Grignard reagents with various dithioesters. A mechanistic... 

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