Carbohydrates cerium oxidation

The oxidation detector for the fluorimetric analysis of carbohydrates in effluents from liquid chromatography columns provides a sensitive method of analysis in blood and urine [110]. The principle involves the reduction of cerium(IV) to cerium(III) by oxidizable compounds such as organic acids and many carbohydrates. The fluorescence... 

Acetyl- and 3-benzoylisoxazoles 389 (and isoxazolines) have been prepared by one-pot reactions of alkynes (and alkenes) with ammonium cerium(iv) nitrate (CAN(lv)) or ammonium cerium(lll) nitrate tetrahydrate (CAN(m))-formic acid, in acetone or acetophenone. These processes probably involve 1,3-dipolar cycloaddition of nitrile oxides produced via nitration of the carbonyl compound by cerium salts. The existence of nitrile oxides as reaction intermediates was proved by the formation of the dimer furoxan 390 when the above reaction was carried out in absence of any dipolarophile (Scheme 95) <2004T1671>. An analogous improved procedure has been applied to alkynyl glycosides as dipolarophiles for the preparation of carbohydrate isoxazoles <2006SL1739>. 

Very recently, cerium(IV)-mediated C-C bond formations were applied for the first time in carbohydrate chemistry [9]. Again, radicals are generated from malo-nates la at low temperatures, and even sensitive glycals 16 are stable under such conditions. The regioselectivity of the additions is controlled by favorable orbital interactions and the adduct radicals are oxidized to cations, which are trapped by the solvent or CAN to afford the carbohydrate C-analogs 17 in good yields (Scheme... 

Indirect methods for the determination of carbohydrates, based on the consumption of an oxidant in their oxidation, have also been developed. For example, a method for the determination of n-glucose, n-fructose, and sucrose was developed, based on their oxidation with cerium (IV) perchlorate in M perchloric acid at 60° and the determination of the amount of unconsumed oxidant by titration with sodium oxalate, with... 

Cyclic ethers are oxidized to lactones in the presence of cerium(IV) salts. Treatment of tetrahydrofu-ran with cerium(IV) ammonium nitrate in the presence of primary, secondary or tertiary alcohols leads to the formation of the corresponding tetrahydroteanyl ethers in quantitative yield. Furthermore, 4-meth-oxybenzyl ether derivatives of carbohydrates are selectively deprotected to the parent alcohols on reaction with cerium(IV) ammonium nitrate in aqueous acetonitrile. " ... 

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