A-Alkylthio nitriles

Mitchell has reported that benzyl a-chlorobenzyl sulfides are cleanly converted into stilbenes on successive treatment with PPhs and Bu OK (Scheme 13). Desulfurization of an intermediate thiirane by PPh3 is a likely pathway for this reaction. Benzyl a,a-dichlorobenzyl sulfides are converted into diphe-nylacetylenes under the same conditions." Viehe has reported that pyrolysis of ot-halo-a-alkylthio esters, ketones and nitriles under reduced pressure furnishes a,p-unsaturated esters, ketones and nitriles respectively it is probable that these reactions also take place via intermediate thiiranes. a-Chlorophenacyl phenacyl sulfide is converted into ( )-dibenzoylethylene on treatment with EtsN. ... 

Properties of Sulphides.—An a-alkylthio-group increases the enol content of jS-dicarbonyl compounds,and causes a shift in carbonyl stretching frequency to lower values, in a-(alkylthio) thioesters, ketones, and amides the C—N stretching frequency in corresponding nitriles is similarly altered. ... 

A novel synthesis of alkylsulfanylisothiazoles 230 starts with sodium a-cyanoketene dithiolates 227, obtained by the reaction of cyanoacetamides 226 with carbon disulfide in the presence of sodium ethoxide <06SC825>. Treatment of 227 with sulphur and piperidine acetate generates sodium isothiazole-3,5-dithiolates 229. The formation of 229 is assumed to arise from the addition of anionic sulphur to the nitrile group in 227 to give the intermediate 228, which cyclizes upon elimination of anionic sulphur to yield 229. Salts 229 are readily alkylated to furnish 3,5-bis(alkylthio)isothiazole derivatives 230. 

Monomeric and dimeric species obtained from the reaction of alkylthio-cyanates with tris(phenylthio)borane have not been isolated in a pure state 32). The reaction of (organothio)dichloroboranes with nitriles as illustrated by... 

Arylthioimidazoles can be made in high yields when thiophenates react with At-(l-cyanoalkyl) alkylidene A -oxides. Alkyl and aralkyl thiolates, however, react much less readily (see Section 2.1.1 and Scheme 2.1.10). Imidazole-4-thioethers can be made in a general reaction between nitriles and a range of isocyanides which are susceptible to o -metallation (see Section 4.2, Scheme 4.2.2 and Table 4.2.1). Oxoketene acetals bearing alkylthio substituents react with nitrosoaromatics to give 5-acyl-4-alkylthio-l-arylimidazoles in moderate to good yields (see Section 3.2 and Scheme 3.2.5). 

In contrast, the photolysis of these azides at 350 nm leads only to the corresponding nitriles and olefins in yields of 90 l-(Alkylthio)cyclopropyl azides (164), readily accessible from the corresponding chlorides and bromides, are smoothly decomposed at ITC with nitrogen evolution. The main process is a ring enlargement to 2-(alkylthio)azetines (165), accompanied by cleavage to an alkyl thiocyanate and an alkene (equation 114). ... 

Mercaptoacetic acid adds very readily to nitriles and, according to Condo and his co-workers85 can be used for direct identification of nitriles it gives the adducts in 80-90% yield when a solution of the nitrile and mercaptoacetic acid in anhydrous ether is saturated at 0° with dry hydrogen chloride. Hydrogen sulfide and thiols add to cyanic esters, giving respectively thiocarbamic esters and (alkylthio)formimidic esters homogeneously, under mild conditions, and in almost quantitative yield 86... 

Recent developments in the retro-Diels-Alder reaction have been reviewed. 1,3-Dipolar cycloadditions of nitrile oxides to 4-aryl-2-alkyIthio-l-azetines gave oxadiazabicyclo[3.2.0]heptenes that undergo a 2 -i- 2-cycloreversion with the loss of a styrene to furnish 5-alkylthio-3-aryl-l,2,4-oxadiazoles (Scheme 1). ... 

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