Sulfides, aryl with Grignard reagents

The nickel-catalysed reaction of aryl, allyl or vinyl sulfides with Grignard reagents has been found to be an effective way for the conversion of carbon-sulfur bonds into carbon-carbon bonds [318]. However, simple aliphatic substrates are inert. 

Spry has reported that cis-P-halo-a,P-unsaturated sulfoxides, on treatment with Grignard reagents, react to form carbon-sulfur bonds, and has used this methodology as part of the preparation of 5(l)-C(2)-secocephems [70], while Posner found that a,P-unsaturated aryl sulfoxides were easily reduced to the corresponding sulfides upon treatment with ethylmagnesium bromide/10% cuprous iodide with retention of double bond stereochemistry [71]. 

This method has been exploited in a synthetic sequence leading to salvinorin A that shows potent K opioid agonist activity. Alkenyl sulfrdes can also be employed as electrophiles in iron-catalyzed cross-coupling reactions with Grignard reagents (Scheme 4-215). The reaction is chemoselective for alkenyl sulfides, whereas aryl sulfides show only very low reactivity. ... 

Perfluoroaryl alkyl sulfides (e.g., 7) can be synthesized by the reaction of Grignard reagents with aryl halides in the presence of elemental sulfur. For example, allyl pentalluorophenyl sulfide (7) is obtained in excellent yield from bromopentafluorobenzene (5) and allyl bromide... 

Sulfides, or thioethers, are sulfur analogues of ethers, and like ethers they can be either symmetrical (R2S) or unsymmetrical (RSR1, where R and R are different). Sulfides can be prepared from alkyl halides by a Williamson-type synthesis with sodium hydrogen sulfide, sodium thiolate or sodium sulfide from alkyl or aryl halides via the Grignard reagent (11) from alkenes by radical-catalysed addition of thiols or by reduction of sulfoxides (Scheme 9).2b... 

Previously, Andersen et al. had attempted to prepare sulfuranes from the reactions of diaryl sulfoxides with aryl Grignard reagents and aryl lithium agents. They reported that the reactions give initially the corresponding triaryl sulfoni-um salts, from which two pathways, namely the formation of tetraaryl sulfuranes and the formation of benzyne, take place simultaneously, on the basis that they obtained diaryl sulfides and biaryls derived from benzyne, as shown in Scheme 7 [37]. 

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