Sulphonate esters chiral

The substituents at the least hindered, primary 6- and 6 -positions reacting preferentially and the other primary substituent, of the more crowded neo-pentyl type at the 1 -primary position, reacting more slowly them the more favorable, but secondary, 4-position. In accord with this mechanism, inversion of chirality is always observed when nucleophilic substitution occurs at a chiral centre, in this case at C-4. By this process, 4-sulphonate esters of sucrose are converted by substitution and inversion of configuration at C-4 into g-D-fructofuranosyl a-D-galactopyranoside (F)... 

Terpenoids are frequently used to introduce asymmetry into molecules (a classic example is isopinocamphenylborane), and the use of camphor to introduce chirality into lanthanide shift reagents is now established (see also the section on bicyclo[2,2,l]heptanes below). The difference in geminal nonequivalence of methylene hydrogens of diastereomeric ( —)-menthoxyacetamides has been used as a monitor for the optical resolution of amines, this being a development of earlier work using menthoxyacetates for diastereomeric alcohols. The optical purity of chiral amines can also be checked from the n.m.r. spectrum of the amides obtained with (-t-)-(lR,4R)-camphor-10-sulphonic acid. Use of a menthol ester to separate pseudoasymmetric ferrocenes has been described. ... 

In contrast, the conversion of cellulose with camphor-10-sulphonic acid via in situ activation with CDI is not efficient to obtain a chiral sulphonic acid ester of cellulose. Only very small amount of sulphonic acid ester functions can be introduced in agreement with results of the chemistry of low molecular weight alcohols regarding a much lower efficiency of CDI for the preparation of sulphonic acid esters [38],... 

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. ... 

---