Sulfoxide, chloromethyl phenyl lithiation

Addition of BuLi to a 0.3 M solution of chloromethyl phenyl sulfoxide in THF at — 78 "C yields an immediate bright-yellow solution containing the lithio derivative which is stable for at least 2 h at —78 rC. Decomposition occurs rapidly above —20 C with the solution becoming turbid and the color changing to dark brown. Reaction of the lithiated solution of chloromethyl phenyl sulfoxide with cyclohexanone, acetone, or ben/ophenone for 10 min at —78 °C followed by 30 min at —20 rC yields one diastereomeT in 79, 75 and 68 % yields, respectively, after hydrolysis of the corresponding adducts. 

The a-chloro-a-sultinyl ketone 20 was prepared from methyl benzoate and chloromethyl phenyl sulfoxide 19 after in situ a-lithiation. Compound 20 is dimetallated by KH and f-BuLi to give the keto dianion 21, which is converted into a potassium/lithium ynolate 22 (equation 7). The resulting metal ynolates are converted into thioesters, carboxylic acids, amides and esters (Section V). 

Durst reported that lithiation of chloromethyl phenyl sulfoxide (99) with butyllithium followed by treatment of a symmetrical ketone (-78 °C to -20 C) affords an adduct (100). This reaction is so highly stereoselective that only one diastereomer is produced. Reaction of (100) with dilute methanolic KOH gives an epoxy sulfoxide (101 equation 25). - °... 

Ring expansion of lactones by reaction of the latter with lithiated chloromethyl phenyl sulfoxide with subsequent treatment with KH and then f-BuLi is a mechanistically intriguing transformation. Episulfone is readily deprotonated. Tris(trimethylsilyl)episulfone has been obtained. A convenient synthesis of trimethylsilylmethyl isocyanate is by Hthiation of... 

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