Sulphinyl

Exchange of organic substituents at the sulphinyl sulphur atom. . 361... 

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... 

A different non-classical approach to the resolution of sulphoxides was reported by Mikolajczyk and Drabowicz269-281. It is based on the fact that sulphinyl compounds very easily form inclusion complexes with /1-cyclodextrin. Since /1-cyclodextrin as the host molecule is chiral, its inclusion complexes with racemic guest substances used in an excess are mixtures of diastereoisomers that should be formed in unequal amounts. In this way a series of alkyl phenyl, alkyl p-tolyl and alkyl benzyl sulphoxides has been resolved. However, the optical purities of the partially resolved sulphoxides do not exceed 22% after... 

Two chiral p-tolylsulphinylmethyl ketones 299 were prepared by decarboxylation of optically active sulphinyl ketoesters 300 which were obtained from (— )-(S)-276 and the... 

Formation of a-sulphinyl carbanions has been widely investigated378,379. Several bases have been found to be suitable for the generation of these carbanions, including the use of... 

Generation of anions a to the sulphinyl group takes place also in 1 -alkenyl sulphoxides and can easily be achieved by using such bases as LDA383-385, t-BuLi386 and n-BuLi (for allenyl sulphoxides)387. 

In this section alkylation, Michael additions, hydroxyalkylation (reaction with carbonyl compounds), aminoalkylation, acylation and some other reactions of a-sulphinyl carbanions will be discussed. 

From the synthetic point of view the most important a-sulphinyl carbanions are the anions derived from dithioacetal S-oxides which may be considered as synthons of acyl... 

The dianion of 2-carboxyethyl phenyl sulphoxide 362 undergoes alkylation at the a-position to the sulphinyl group440,441 (equation 205). 

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