Carbohydrates as starting materials

The first efforts to use carbohydrates as starting materials for the chemical industry in Europe were made with a conference held at Technische Hochschule Darmstadt, Germany, and a corresponding monograph edited by Frieder Lichtenthaler [11]. 

Scheme 14 Two examples of the chiral substrate approach a carbohydrates as starting materials for the construction of chiral enynes b epichlorhydrin as source of chirality in assymetric PKRs...

In the case of the cydohexadienediols 6, the current development promises to complement the traditional and rather arduous use of carbohydrates as starting materials from the chiral pool. The popularity of diol-based methods will, therefore, be directly proportional to their ready commercial availability and to the operational... 

Chiral furo[2,3- ]furans can be obtained in a synthetic strategy which utilizes carbohydrates as starting materials and is shown in Scheme 17 o-xylose has been converted to the intermediate 56 which, in the presence of tributyltin hydride, gives the bicyclic product 57 in high yield. 

Carbohydrates have been used as chirons to generate a number of interesting furan derivatives from industrial commodities such as 2-furaldehyde, to more complex, biologically significant compounds with therapeutic potential. Several interesting examples of the use of carbohydrates as starting materials for the synthesis of furans are highlighted below. 

Volume 36 will be dedicated to carbohydrate-based vaccines and to the utilization of the azide functionality in chemical and biological areas of the glycosciences. There are recent reports on interesting applications of azides in this area, and as starting materials for a variety of important bioactive carbohydrates. Hence, the synthesis, reactivity and application of azides in glycomics will also be included in this volume. 

The availability, in gram quantities, of the fluorinated carbohydrates thus far synthesized has also made possible their use as starting materials for the synthesis of other analogs and intermediates for example, the preparation of 3,5-dideoxy-3,5-difluoro-D-xylose from 3-deoxy-3-fluoro-D-xylose,88 which is itself preparable from 3-deoxy-3-fluoro-l,2-0-isopropylidene-a-D-glucofuranose. Electrolytic oxidation of 3-deoxy-3-fluoro-D-glucose afforded, after treatment with an acidic... 

Several syntheses of D-lividosamine and its derivatives have already been reported. They use carbohydrates or optically pure but-3-ene-l,2-diol as starting materials. ... 

The synthesis in Scheme 13.34 also begins with carbohydrate-derived starting material and also uses catalytic hydrogenation to establish the stereochemical relationship between the C-4 and C-6 methyl groups. As was the case in Scheme 13.33, the configuration at C-2 is not controlled in this synthesis, and separation of the diastereomeric products was necessary. 

Owing to the possibility of tuning (1) their acidic and basic properties, (2) their surface hydrophilicity, and (3) their adsorption and shape-selectivity properties, catalytic activity of zeolites was investigated in the production of HMF from carbohydrates. Whatever the hexose used as starting material, acidic pillared montmorillonites and faujasite were poorly selective towards HMF, yielding levu-linic and formic acids as the main products [81-83]. 

Some of the main biosynthetic pathways begin with intermediates in the TCA cycle. When intermediates in the cycle are used as starting materials for biosynthesis, they must be replenished to keep the cycle operating. When carbohydrates are being metabolized, TCA cycle intermediates are replenished by production of oxaloacetate from pyruvate. 

Some carbohydrates are inexpensive and provide a great variety of functional and stereochemical features. Faithful to our philosophy that low-cost starting materials should be utilized, we shall discuss some reactions of glucose and syntheses with glucose as starting material. Structures of glucose derivatives and other commercially available carbohydrates are given below. 

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