Chiral sulphones synthesis

The preparation of (silyloxy)rhodium complexes of the type [Rh2(fi-OSiR3)2(Ti -COD)2l (R = Me, Ph), which could serve as models of rhodium complexes bound to silica, has been reported238. The synthesis of the water-soluble complex [Rh(Ti -COD)(DPPETS)]+[Cl]" (DPPETS = l,2-bis bis(m-sodiosulfonatophenyl)phosphino ethane) has been reported and its catalytic activity in two-phase hydroformylation reactions investigated. The mechanism of the homogeneous reduction of (Z)-a-acetamido and (Z)-a-benzamidocinnamic acid methyl ester and a-acetamidoacrylic acid methyl ester in an organic-water medium in the presence of catalysts derived from [Rh2(lt-Cl)2(Ti -COD)2] and chiral sulphonated phosphines has been investigated W. ... 

The utilization of carbohydrates for the synthesis of chiral crown ethers has been further explored, giving derivatives with the general structures (12) and (13) using 4,-6-O-benzylidene derivatives of methyl a-o-galacto-, gluco-, and manno-pyranoside in a base-catalysed reaction with diethylene glycol bis-toluene-p-sulphonate. ... 

If the lone pair in (38) or (39) is replaced by a double bond to oxygen the resulting sulphone is obviously achiral but if it is instead replaced by a double bond to nitrogen, we get another type of chiral sulphur compound, the sulphoximines (40) which have also been used for asymmetric synthesis (see section 5.1.3). The sulphonium salts (41) are also potentially chiral. A review of the chiral compounds of sulphur is available,... 

The sulphonyloxaziridines (70) and (71) derived from (-h)- and (-)-camphor-sulphonic acid are very useful for the asymmetric synthesis of a-hydroxycarbonyl compounds, which are important and widely distributed. The reaction is performed simply by treating the prochiral enolate with the chiral oxidant, as in the example shown for preparation of either enantiomer of benzoin. 

Intermediates in Reactions.— The utility of the Ramberg-Backlund rearrangement and the involvement of thiiran 1,1-dioxides in synthesis has been reviewed. Treatment of d,l- and meso-bis-oc-bromobenzyl sulphone with triphenylphosphine gave trans- and cis-stilbene, respectively, via a-sulphonyl carbanions which undergo cyclization at the remaining chiral centre to yield trans- and cis-2,3-diphenylthiiran 1,1-dioxides as intermediates (Scheme 3). Inversion occurred at each chiral centre. Thiiran... 

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