Thioethers reactions with magnesium

Reactions of allyl and benzyl ethers and thioethers with magnesium... 

A similar reaction has been described for the preparation of thioethers with aryl-and alkylthiotrimethyl silanes.Ring-closure occurs with co-bromo-1,2-epoxyalkanes on the action of magnesium and lithium in the presence of Cul. By this means, cyclobutanol, cyclopentanol, and cyclohexanol can be prepared. (e.g. Eq. 294). 

Synthetic uses. Arens,° in reviewing the many reactions of ethynyl ethers and thioethers, states that the first use of ethoxyacetylene for the synthesis of a,/3-unsaturated aldehydes was described in a paper published in Russia in 1945, but that the paper was abstracted incorrectly and remained unknown in the western world, van Dorp and Arens" rediscovered the method and in 1947 described its use in the synthesis of vitamin A aldehyde. Ethoxyacetylene is treated with ethyl-magnesium bromide to form the Orignard reagent, and this is added to the carbonyl group of the "C lii-kelone" to produce the acetylenic cnrbinol (I). Semlhydrogenation... 

A synthesis of 2-alkyl- or 2-aryl-substituted benzo[Z>]thiophens consists of the cyclization of an aryl thioether with an acetonyl or phenacyl group in the or/Ao-position (315) with 48% hydrobromic acid. In order to obtain (315 R = Ph), 2-methylthiobenzyl cyanide is treated with phenyl-magnesium bromide. The reaction of or//to-methylthiostyrene derivatives, especially cinnamic acids (316), with sulphuryl chloride followed by pyridine, probably gives the benzo[6]thiophens (318) via the sulphenyl chloride (317). ... 

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