Aldonic acids modified

Esters, lactones, lactams, acyl halides etc. are named by modifying the ending -ic acid as described for aldonic acids (2-Carb-20.2). 

The first surface-initiated enzymatic polymerization reported was the synthesis of amylose brushes on planar and spherical surfaces [145]. For this, silica or silicone surfaces were modified with self-assembled monolayers of (3 amino-propyl)trimethoxysilane or chlorodimethylsilane, respectively. To these functionalities, oligosaccharides were added via (a) reductive amidation of the oligosaccharides to surface-bound amines, (b) conversion of the oiigosaccharide to the according aldonic acid lactone and reaction with surface bound amines, and (c) incorporation... 

This section deals with acids, that are formally modified aldonic acids, such as keto, deoxy, and branched-chain acids (including the so-called saccharinic acids). The aminoaldonic acids, which are oxidation products of amino sugars, and, in particular, the important nonulosaminic acids (neuraminic acids) and muramic acid, are not discussed here. The formation of saccharinic acids by the treatment of sugars with alkali, and the mechanisms involved, are likewise outside the scope of this chapter. 

P. C. C. Smits, B. F. M. Kuster, K. Van der Wiele, and H. S. Van der Baan, The selective oxidation of aldoses and aldonic acids to 2-ketoaldonic acids with lead-modified platinum-on-carbon catalysts, Carbohydr. Res., 153 (1986) 227-235. 

In the first step of the synthesis (the Kiliani portion), the aldose is treated with sodium cyanide and HCl (Section 18.4). Addition of cyanide ion to the carbonyl group creates a new asymmetric carbon. Consequently, two cyanohydrins that differ only in configuration at C-2 are formed. The configurations of the other asymmetric carbons do not change, because no bond to any of the asymmetric carbons is broken during the course of the reaction (Section 5.12). Kiliani went on to hydrolyze the cyanohydrins to aldonic acids (Section 17.18), and Fischer had previously developed a method to convert aldonic acids to aldoses. This reaction sequence was used for many years, but the method currently employed to convert the cyanohydrins to aldoses was developed by Serianni and Barker in 1979 it is referred to as the modified Kiliani-Fischer synthesis. Serianni and Barker reduced the cyanohydrins to imines, using a partially deactivated palladium (on barium sulfate) catalyst so that the imines would not be further reduced to amines. The imines could then be hydrolyzed to aldoses (Section 18.6). 

Also a new end point attachment of nondegraded glycosaminoglycan type 2 (HE) or regioselective modified heparin derivatives will be described the reducing end is oxidised by electrolysis and the aldonic acid lactone formed reacts with amino groups of the polymer surface. Also coatings by ionic immobilisation (HE, ES-HS) will be described. 

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