Sulfoxides from Grignard reagents

Satoh, T. Takano, K. Ota, H. Someya, H. Matsuda, K. Koyama, M. Magnesium alkyl-idene carbenoids generation from 1-halovinyl sulfoxides with Grignard reagents and studies on the properties, mechanism, and some synthetic uses. Tetrahedron 1998, 54, 5557-5574. 

Other Applications. Thionyl chloride has been used to convert epoxides to vicinal dichlorides and for the preparation of dialkyl sulfides from Grignard reagents. Phenols react with SOCI2 to produce aryl chlorosulfites and diaryl sulfites or nuclear substitution products. As shown in eq 14, Aluminum Chloride catalysis yields symmetric sulfoxides, while in the absence of Lewis acids, aromatic thiosulfonates are the principal products. Primary amines, especially aromatic ones, react with SOCI2 to produce N-sulfiny lamines, which are potent enophiles and useful precursors to some heterocyclic compounds. ... 

The most important and widely used approach to chiral sulfoxides is the method developed by Andersen (5) based on the reaction between the diastereomerically pure (or strongly enriched in one dia-stereomer) menthyl arenesulfinates and Grignard reagents. The first stereospecific synthesis of optically active (+H7 )-ethyl p-tolyl sulfoxide 22 was accomplished in 1962 by Andersen (75) from (-)-(iS)-menthyl p-toluenesulfmate 45 and ethylmagnesium iodide. 

The most important and w idely used approach to sulfoxides of high optical purity is based on the reaction of diastereomerically pure menthyl arenesulfinates with Grignard reagents. ( + )-(A)-l-Ethylsulfinyl-4-methylbenzene, prepared from (- j-menthyl (S)-4-mcthylbenzene-sulfmate and ethylmagnesium bromide, was the first optically active sulfoxide obtained by this method 13. 

As mentioned above, the configuration of the magnesium carbenoid is rather stable at low temperature chiral Grignard reagents having over 90% ee could be generated from optically active 1-chloroalkyl aryl sulfoxides (Scheme 4)20-22... 

Chiral 2,2-disubstituted cyclobutanones have been obtained by asymmetric rearrangement of chiral sulfinyl- 177,178 and sulfanylcyclopropanes.179 Using readily available cyclopropyl 4-tolyl (/ )-sulfoxide (l),180 the requisite sulfinylcyclopropanes 3 and 3 were obtained by a sequence of lithiation, reaction with carboxylic acid esters and stereoselective addition of Grignard reagents to the ketones 2 thus formed.178 The corresponding sulfanylcyclopropanes 4 and 4 resulted from a sequence of protection, reduction and deprotection.179... 

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