Sulfenate anion, alkylation

Madec and Poli recently reported that sulfenate anions can also be used as nucleophiles in catalytic formation of C ryi-S bonds, generating sulfoxides [103]. The sulfenate anions are generated in situ by base-induced elimination of (3-sulfinyles-ters [136]. These groups subsequently developed an enantioselective variant, allowing the asymmetric synthesis of sulfoxides with up to 83% ee (16) [105]. Chiral sulfoxides are present in a variety of pharmaceuticals and are widely used in asymmetric catalysis [137-141]. Likewise, Madec and Poli found that sulfenate anions can be used to generate Csp -S bonds in Pd-catalyzed allylic alkylation [ 142]. o... 

Generation of the sulfenic acid anion using a weak base gives excellent yields of the isothiazolone (43) (Chou et al., 1974). It was possible to suppress this rearrangement by use of lithium diisopropylamide at - 126°C, which, when followed by methyl fluorosulfonate alkylation, afforded the methyl sulfenate (52) in good yield (Koppel and Kukoija, 1975). This alkylation of the sulfenate anion occurs exclusively on ox-... 

The Pd-catalyzed allylic alkylation strategy was also applied to the synthesis of allyl sulfoxides 318 by Poli et al. The use of sulfenate anions 319 (Scheme 46.37), generated from 3-sullinylesters 317 by a retro-Michael reaction under biphasic conditions, is noteworthy. 

Maitro G, Prestat G, Madec D, Poli G. Preparation of allyl sulfoxides by palladium-catalyzed allylic alkylation of sulfenate anions. J. Org. Chem. 2006 71 7449-7454. 

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