Sulfenate anions

Generation of sulfenate anion is convenient from RS(=0)CH2CH2SiMe3. ... 

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... 

Scheme 18.63 Allyl sulfoxide as a sulfenate anion source in cross-coupling route to aromatic sulfoxides.—...

Generation of Sulfenate Anions for Pd-Mediated Cross-Coupling... 

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. 

The same authors also demonstrated the palladium-catalyzed arylation of in situ generated sulfenate anions, but the catalytic asymmetric conditions provided products 321 with a modest level of enantioselectivity in the presence of Josiphos-like ligands 320. The use of ir-aUylpalladium/ mthenium complexes was also extended to the carbonylation into C S bonds of various allylic sulfides 322 in good to excellent yields by Crudden and Alper. The reaction was... 

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. 

Maitro G, Vogel S, Sadaoui M, Prestat G, Madec D, Poh G. Enantioselective synthesis of aryl sulfoxides via palladium-catalyzed arylation of sulfenate anions. Org. Lett. 2007 9 5493-5496. 

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