8-Hydroxycarboxylic - - special

Other multifunctional hydroxycarboxylic acids are mevalonic and aldonic acids which can be prepared for specialized uses as aldol reaction products (mevalonic acid [150-97-0] (13)) and mild oxidation of aldoses (aldonic acids). 

The chemistry of silicon oxygen compounds with SiOs and SiC>6 skeletons in aqueous solution is of special interest. It has been speculated that such Si(IV) complexes with ligands derived from organic hydroxy compounds (such as pyrocatechol derivatives, hydroxycarboxylic acids, and carbohydrates) may play a significant role in silicon biochemistry by controlling the transport of silicon. 

Recently, we succeeded in developing syntheses of dianionic A, 5 i-silicates with SiOe skeletons containing three unsymmetric bidentate ligands. These ligands derive from (i) aceto- or benzohydroximic acid, (ii) a-hydroxycarboxylic acids (such as glycolic acid and benzilic acid), or (iii) 6-hydroxycarboxylic acids of the salicylic acid type. In the case of such unsymmetric bidentate ligands, special stereochemical features have to be considered, i.e. fac/mer-isomehsm and yl/d-enantiomerism. 

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