Thioketones reactions with Grignard

Reactions of different organometallic species with thiocarbonyi compounds have been extensively investigated and been shown to proceed both in a carbophilic and a thiophilic fashion. However, other reactions can be observed simultaneously such as reduction, double addition, coupling, deprotonation and formation of enesulfides1,226,423. A complex pattern appears in the reactions of thioketones with lithium or Grignard reagents424. The first application of Reformatsky reagents in C—C bond formation by reaction with... 

Only a few studies have been made on this reaction. Saturated Grignard reagents react with a, -ethylenic thioketones [28,29] to lead to a mixture of several products. They principally result from thiophilic 1,2-addition, thiophilic 1,4-addition, and 5-alkylation [28,29]. 

Reaction of thioketones with Grignard compds. Tert. mercaptans and sec. thioethers... 

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... 

A variation of the use of thiourea for converting alkyl halides into thiols uses N-acetylthiourea although reaction with an alkyl halide in refluxing EtOH is slow, a separate hydrolysis step is not required and the method may prove useful for the synthesis of water- or alkali-sensitive thiols. Other methods based upon thiocarbonyl derivatives are exemplified by the addition of allylic Grignard reagents to thioketones, giving 7-unsaturated... 

Several sulphur-containing heterocyclic compounds have been found convertible into thioketones by appropriate ring-opening reactions. Thus N-(S-aryl-3H-l,2-dithiole-3-ylidene)arylamines reacted with Grignard reagents with cleavs e of the S—S bond to give the thiones (41). The thiones... 

Considering these results, it can be clearly concluded that Grignard reagents do not react with thioketones exclusively according to a thiophilic mechanism. However, the same conclusion appears to be justifiable also with respect to other organometallic reagents. According to a very recent paper," adamantanethione is indeed subject to a thiophilic attack by butyl-lithium to a certain extent, but a C-alkylation product is formed preferentially by its reaction with prenyl-lithium (Scheme 4). 

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