Long-chain carbohydrates

Use of Unstabilized Carbohydrate Ylides for the Synthesis of Long-Chain Carbohydrates... 

To summarize, unstabilized carbohydrate phosphoranes are useful entities for the synthesis of long-chain carbohydrates by a Wittig process as long as the proper experimental conditions are employed and as long as the 6-oxygen is attached by another set of bonds to... 

The methods often used for the branching of carbon chain are also suitable for the chain extension of sugars at both ends (e.g., C-l and C-5/C-6). Several developments of chain extension have recently culminated in the synthesis of long-chain carbohydrates of biological interest. 

Cell materials are either water-soluble or water-insoluble. The smaller building blocks of cells like amino acids and glucose are water-soluble, but the large molecules they eventually synthesize, like proteins, cell walls, fats and long-chain carbohydrates are water-insoluble. This is a subtle but significant fact. The water-soluble units can be carried around the body in aqueous solutions to sites where they are needed, but once a new larger molecules are synthesized then these are water-insoluble and so cannot be removed from the cell unless an enzyme or chemical attack takes place to break them up. 

The possible ionic nature of the small molecules of amino acids means that they can form zwitter ions. The large number of OHs in glucose helps it to be water soluble, whereas the compounds it synthesizes, proteins and long-chain carbohydrates, are large molecules with molecular masses of greater than 20 000, and this prevents them from dissolving in water. 

SCHEME 13.98 Cross-aldol reactions with naked sugars. Syntheses of long-chain carbohydrates, indolizidines and analogs. 

Polysaccharides are long-chain carbohydrate molecules composed of monosaccharides held together by ether linkages called glycoside bond. Their molecular formula is C (HjO) where x can be between 200 and 2500. 

A review on the synthesis and reactivity of sugars with two branches at C-3 has appeared, as well as another on the synthesis of rare carbohydrates which includes the application of "naked sugars" to the synthesis of branched, long chain carbohydrates amongst the topics covered. ... 

Glycogen Branched long-chain carbohydrate serving as an energy store. 

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