Allyl sulphur compounds

A number of reports have focused interest on the synthesis of various allylic sulphur compounds. A one-pot procedure for the preparation of allylic sulphides from the corresponding alcohols involves initial rearrangement of the xanthate followed by... 

These allyl sulphur compounds lower the activity of microsomal cytochrome by three different mechanisms ... 

The allyl sulphur compounds (section 7.5.2.1) in garlic inhibit platelet coagulation, and again have a potentially beneficial effect with respect to thrombosis. 

The allylic ion (XI) is probably too stable to propagate the reaction. The inhibiting (poisoning) effect of oxygen, nitrogen, and sulphur compounds is also due to formation of stable ions (in so far as it is not due to sequestration of metal halide by complex formation), e.g., the reaction [98] ... 

Thio-ethers.— Ethers derived from the unsaturated hydrocarbons are known but are not important. The corresponding sulphur compounds, viz., the thio-ethers, are, however, of considerable importance and are represented by a commonly occurring substance. The thio-ether related to allyl alcohol is known as allyl thio-ether, or, also as allyl sulphide. It is made, like the thio-ethers of the saturated series, by treating the iodide of the hydrocarbon with potassium sulphide. 

In analogy with the sulphur compounds, alkenyl, aryl, and allylic selenides smoothly couple with Grignard reagents in the presence of catalytic quantities of nickel(ll)-phosphine complexes to give unsaturated hydrocarbons (e.g. Scheme 25). Allylic selenides react by both direct and 1,3-substitution to give regioisomeric mixtures of products. 

Allylic primary amines have been prepared by the allylic amination of olefins and acetylenes by imido-sulphur compounds (Scheme 3), and also from the ring opening of vinylaziridines by hydroboration. ... 

Vulcanisation can be effected by diamines, polyamines and lead compounds such as lead oxides and basic lead phosphite. The homopolymer vulcanisate is similar to butyl rubber in such characteristics as low air permeability, low resilience, excellent ozone resistance, good heat resistance and good weathering resistance. In addition the polyepichlorohydrins have good flame resistance. The copolymers have more resilience and lower brittle points but air impermeability and oil resistance are not so good. The inclusion of allyl glycidyl ether in the polymerisation recipe produces a sulphur-curable elastomer primarily of interest because of its better resistance to sour gas than conventional epichlorhydrin rubbers. 

The allyl 2-nitrophenyl sulphoxide is apparently not an intermediate in this reaction as the MS of the latter compound is dominated by a cleavage reaction giving rise to C3H5+, whereas the ions corresponding to a loss of the HSC>2 radical apparently are of low intensity86. Thus, it was concluded that the double oxygen transfer to sulphur most probably should be formulated as a concerted reaction86. 

Ethylene and thioformaldehyde are the products of irradiation of matrix-isolated thietane at lOK. Sulphur-carbon bond homolysis has also been observed on irradiation of the nucleoside membrane transport inhibitor, 6-[ (4-nitrobenzyl) thio] -9- (/8-D-ribofuranosyl) -purine (94), and the oxazolidin-2-one (95) has been converted into the allyl derivative (96) by photochemically induced radical allylation.Efficient conversion of cyclic thioacetals into the corresponding carbonyl compounds under neutral conditions has been achieved by 2,4,6-triphenylpyrylium tetrafluoroborate-sensitised irradiation in moist dichloromethane,and diaryl sulphides and the corresponding sulphoxides and sulphones have been reported to undergo anion-promoted carbon-sulphur bond photocleavageboth processes appear to involve an initial electron transfer. Sulphur-hydrogen bond horaolysis has been reported in t-butanethiol and is also responsible for the photoinitiated thiylation of fluorobromoethylenes and of trialkylethynylsilanes and t-butylacetylene. 

NBS (12) was used for the allylic bromination. Thiol synthesis needs protection for sulphur (see Chapter 5) and an ester can be used. The nitro compound was also protected as an ester so that nitroethylene was released into the reaction mixture. 

A colourimetric method was developed for determination of allyl isothiocyanate, with a detection limit of ca 1 g S. It is based on alkaline hydrolysis to yield sulphide ions, which subsequently react (as shown in equation 40) to yield methylene blue, which in turn is measured at 665 nm. The following sulphur-containing compounds were tested as possible interference with the method Thioacetamide, thiourea, cysteine, methionine, cysteic acid. 

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