Sulphinyl chlorides

E. Reaction of Aromatic Derivatives and Compounds Containing Active Hydrogen with Sulphinyl Chlorides... 

Up to now this possibility was applied for the preparation of a-ketosulphoxides. The first formation of a-ketosulphoxides in the reaction between a ketone and sulphinyl chloride was reported by Oae and Ikura188 in 1966. They prepared p-nitrobenzene-sulphinyl chloride and identified it by means of its reaction product with acetone which had the analytical composition of a-sulphinylacetone 134 (equation 73). 

The ethylaluminium dichloride-catalyzed reaction of p-toluenesulphinyl chloride with alkenes 136 successfully applied191 for the synthesis of allylic sulphoxides 137 (equation 74) may also be regarded formally as a reaction of sulphinyl chlorides with compounds containing active hydrogen atom. Treatment of an alkene 136 with one equivalent each of ethylaluminium dichloride and p-toluenesulphinyl chloride at room temperature gave the corresponding 137. This reaction is very general and proceeds in... 

The addition of sulphinyl chlorides to trimethylsilyl enol ether 138 affording a-ketosulphoxides 139 (equation 76) represents an extension of the reaction of sulphinyl chlorides with ketones. This reaction has attracted attention only recently. Sergeev and coworkers192 reported that treatment of sulphinyl chlorides with acyclic enol ethers afforded a-ketosulphoxides 139 in good to excellent yields. Meanwell and Johnson193 observed that in the case of cyclic enol ethers the corresponding sulphoxides were formed only in very low yields. They found, however, that the introduction of an equivalent amount of a Lewis acid into the reaction mixture markedly promotes the desired reaction, whereas the use of catalytic amounts of a Lewis acid led to a substantial reduction in the yield. This is most probably due to the formation of a complex, between the a-ketosulphoxide and the Lewis acid. 

TABLE 11. /i-Chlorosulphoxides from sulphinyl chlorides, RSOC1, and unsalu-rated compounds, R CH=CH2... 

As has been mentioned in an earlier section, aqueous chlorination of sulphoxides leads to sulphones. If excess reagents are used, sulphonyl chlorides may be formed directly from sulphoxides in good yields (equation 75)89,90,193. In order for this reaction to be synthetically useful, the sulphoxide used should be symmetrical. The product is presumably formed in a stepwise manner via the sulphinyl chloride [RS(0)C1] and the sulphinic acid [RS(0)0H]. In the case of chloromethyl dichloromethyl sulphoxide, the only sulphonyl chloride formed is chloromethanesulphonyl chloride (equation 76) and this may be readily separated from the other products by distillation90,193. Similarly, oxidation of dichloromethyl methyl sulphoxide and methyl trichloromethyl sulphoxide with chlorine in aqueous acetic acid leads to the formation of methanesulphonyl chloride in 75% and 86% yields respectively. Other species are also produced but these are much more volatile and thus easily removed (equations 77 and 78). In the absence of acetic acid the yields are somewhat reduced. 

TABLE 11. /1-ChlorosuIphoxides from sulphinyl chlorides, RSOCI, and unsaturated compounds, R CH CHj... 

Reaction of diazomethane with sulphinyl chlorides has been known since 1957. Effective procedures for the synthesis of -halogenosulphoxides 217 based on this reaction were reported by Venier and coworkers . Treatment of alkane or arenesulphinyl chlorides with diazomethane in ether solution gives a-chlorosulphoxides 217a in 70-90% yields. When the same reaction was carried out in the presence of iodide anion it yielded the corresponding iodo derivatives 217b in high yields (equation 123). Bromomethyl trichloromethyl sulphoxide was isolated in 15% yield after treatment of trichloro-methanesulphinyl bromide with diazomethane (equation 124). 

Sulphinyl chloride, SOClg, is made by the action of SO2 on PCI5 ... 

Some sulphinyl chlorides have been shown95 to react with silicon-nitrogen compounds or amines to give the sulphinamides (16) and (17). The compounds are reactive intermediates, reacting with trichloromethanesulphenyl chloride and PC15 to form (18) and (19). Compound (19) is cleaved by thermolysis to form sulphinyl chlorides and the trimeric phosphonitrile... 

Aryl sulphonyl chlorides may also be synthesized from the sulphinyl chloride, by oxidation with chlorine, in 80% yield573 (equation 146) or dimethyl sulphoxide574. Sulphinate esters may also be utilized as the precursor to sulphonyl halide via oxidative halogenation. For example, methyl methanesulphinate is converted to methanesulphonyl chloride in excellent yield at 0°C568. 

Methane sulphinyl chloride and para-nitrobenzenesulphinyl chlorides have been used to reduce sulphoxides to sulphides584. During this process, the sulphinyl chloride is oxidized to the corresponding sulphonyl chloride, by direct oxygen transfer. However, it is hard to see how this reaction could be synthetically useful for the preparation of sulphonyl chlorides. 

Solid powdered 2-methoxynaphthalene treated with thionyl chloride at ambient temperature and processed after 1 hour gave the 1-sulphinyl chloride in 91% yield, a route which presumably could be developed to obtain the sulphonic acid (ref. 118). 

Methane- and benzene-sulphinyl chlorides react with azulene to give - ulphoxides [107], Methanesulphonyl chloride, but not benzcnesulphonyl chloride, gives a -sulphone [107], Sulphur di-diloride reacts with azulene to give a bis( 1-azulcnyl) sulphide [ 108]. 

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