Sulfoxides reaction with

Scheme 1.25 Test reaction with sulfoxide-oxazoline ligands.

D. Silver-Mediated Oxidation Reactions with Sulfoxides and Sulfides / 34... 

The preparation of a-selenoketones, esters, nitriles and related compounds can easily be performed via alkylation of the corresponding enolates or stabilized carbanions [21]. These compounds have found many synthetic applications in radical chemistry. In Eq. (9), a typical example involving a ketone is depicted [22]. The stability of a-selenoketones such as 41 is remarkable. Similar reactions with lactones have been performed. For instance, this approach has been applied to the stereoselective synthesis of oxygen-containing rings to either faces of a bicyclic structure [23]. The approach based on a-selenenylation/radical allyla-tion compares favorably with classical enolate allylation procedures, which usually leads to mixture of mono- and diallylated compounds. Furthermore, this strategy is excellent for the preparation of quaternary carbon centers [24] as shown by the conversion of 43 to 45, a key intermediate for the synthesis of fredericamycin A, [Eq. (10)] [25]. Similar reactions with sulfoxides [26] and phosphonates [27] have also been reported. 

The toluenesulfonamide anion being expected to have a greater leaving ability than the oxyanion in the analogous sulfoxide reaction (see section 3.2.4.1), the rate of formation of the tetraarylsulfurane should be increased in comparison with the rate of decomposition by the arynic route. Accordingly, the yield of m,p-bitolyl (111) appeared considerably lower (1-2%) in the reaction of the iV-tosylsulfilimine (112) compared to the yield (26%) obtained in the reaction with sulfoxide (107). ... 

Reaction with Sulfoxides and Phosphine Oxides. Sulfoxides and phosphine oxides can be reduced to the corresponding sulfide and phosphine in the presence of triflic anhydride and a mild reducing agent. 

Reaction with Sulfoxides. DAST reacts with a-hydrogen containing dialkyl and aralkyl sulfoxides to form a-fluoroalkyl sulfides in high yields (eq 17). This reaction can be extended to less reactive sulfoxides by catalysis with certain Lewis acids, e.g. Antimony(IU) Chloride (eq 18) and Zinc IodideP... 

---