Aldonic acids lactonization

Pfannemtiller et al. showed that it is possible to obtain carbohydrate-containing amphiphiles with various alkyl chains via amide bond formation. For this, mal-tooligosaccharides were oxidized to the corresponding aldonic acid lactones, which could subsequently be coupled to alkylamines [128-136]. Such sugar-based surfactants are important industrial products with applications in cosmetics, medical applications etc. [137-139]. The authors were also able to extend the attached mal-tooligosaccharides by enzymatic polymerization using potato phosphorylase, which resulted in products with very interesting solution properties [140, 141]. 

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... 

Hudson lactone rule. The value of the rotation of aldonic acid lactones is decisively affected by the configuration of that carbon atom whose hydroxyl group is engaged in the cyclization. If, in the normal Fischer projection formula, the lactone ring is written on the right, the lactone is dextrorotatory if it is written on the left, the lactone is levorotatory. 

Isolation of Aldonic Acid Lactones through their Hydrazides, Alva Thompson and M. L. Wolfrom,/. Amer. Chem. Soc., 68, 1509-1510 (1946). 

Addition of hydroxylamines on the double bond of the unsaturated aldonic acid lactones 497 gave the isoxazolidin-3-yl acyclo C-nucleosides 499 (92T10363) (Scheme 127). 

Aldonic acid lactones from carbohydrates CHOH CO... 

Bis-(3-methijl-2-butijl)borane Carbohydrates from aldonic acid lactones Aldofuranoses... 

Lactones have also been found to be competent substrates for the Schollkopf oxazole synthesis. For example, treatment of aldonic acid lactone 40 with ethyl a-isocyanoacetate (8) and 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) at ambient temperature provided acyclie sugar oxazole 41 in 49% yield. ... 

Partially and totally acetylated aldonic acids from aldonic acid lactones... 

Cyclocondensation of l-alkylamino-l-deoxy-D-/Arco-pentuloses with ethyl acetoacetate led to iV-alkyl-pyrrole derivatives (24). Aldonic acid lactones react with ethyl isocyanoacetate in presence of DBN to yield oxazole derivatives, e.g. 2,3 5,6-di-0-isopropylidene-D-mannono-l,4-lactone yields the oxazole (25), whereas with potassium hydride as base octenonate derivatives... 

Acyclic sugar oxazoles formed on treatment of protected aldonic acid lactones with ethyl isocyanoacetate and base in an aprotic medium are referred to in Chapter 17. 

Alder s. Diene syntheses Aldofuranoses 19, 50 Aldonic acid lactones... 

Aldonic acids usually yield crystalline lactones, amides and other derivatives and have proved of value in the characterisation of sugars. No appreciable amounts of aldonic acids have been found in plants or animals, although certain bacteria are capable of oxidising glucose and other aldoses to the corresponding aldonic acids. Lactones have proved to be powerful inhibitors in certain enzymic reactions involving substances having structures related to the inhibitors . 

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. 

We have developed a new method for end point attachment. The reducing end of ES-HS and HE was oxidised by electrolysis to an aldonic acid followed by lactonisation according to a method by Emmerling and Pfannemiiller for oligomaltose. The aldonic acid lactone reacted immediately with primary amino groups on the polymer surfaces. 

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