Synthesis of sugars

Giesehas used this strategy for the synthesis of sugar derivadves, as shown in Eq. 7.82. 

We also know that the process of incorporating C02 into complex molecules (that result finally in the synthesis of sugar) is very similar to the reverse of the process of sugar breakdown. These reactions are complicated, however, and will not be discussed here. 

There is a second large gene duster, about 35kb, also involved in the synthesis of xanthan. The predse function is unknown but it is thought to encode for proteins involved in the synthesis of sugar nucleotide diphosphates. 

Two-step synthesis of sugar-containing polyesters by lipase CA catalyst was reported (Scheme 13)." Lipase CA catalyzed the condensation of sucrose with an excess of divinyl adipate to produce sucrose 6,6 -O-divinyl adipate, which was reacted with a,oo-alkylene diols by the same catalyst, yielding polyesters containing a sucrose unit in the main chain. This method conveniently affords... 

Another example of the ability of proteinogenic amino acids, small peptides, and amines to catalyse the formation of new C-C bonds has been demonstrated by Weber and Pizzarello they were able to carry out model reactions for the stereospecific synthesis of sugars (tetroses) using homochiral L-dipeptides. The authors achieved a D-enantiomeric excess (ee) of more than 80% using L-Val-L-Val as the peptide catalyst in sugar synthesis (in particular D-erythrose) via self-condensation of glycol aldehyde. 

R. Roy, S. K. Das, F. Santoyo-Gonzalez, F. Hemandez-Mateo, T. K. Dam, and C. F. Brewer, Synthesis of sugar-rods with phytohemagglutinin cross-linking properties by using the palladium-catalyzed Sonogashira reaction, Chem. Eur. J., 6 (2000) 1757-1762. 

Rauter s group exploited the synthesis of sugar derived bicyclic butenolides ( e.g. 140, Fig. 44),60 which possess cytotoxic and antitumor activities. The key structural feature of such compounds consists of the presence of the a,(3-unsaturated lactone, which allows them to act as Michael acceptors for the addition of enzymes nucleophiles. 

Chapter 19 - The results of experimental researches on the synthesis of sugars derivatives with glycosylamide and thioamide bonds have been presented in this work. The possibility of using their in the preparative chemistry of sugars, some fields of medicine and agriculture has been shown. 

Two bases approaches are used in the synthesis of sugar carbamides direct interaction of carbohydrates with carbamides and their analogs in the conditions of acid catalysis (a) and interaction of acetylation N-glycosylisothiocyanates with amines (b) or interaction of acetylation N-glycosylamines with arylisothiocyanates (c) [3],... 

Scheme 44 Synthesis of sugar-1,2-fused iodobutyrolactones from sugar-1,2-fused cyclopropa-nated esters...

The first application of this reaction for the synthesis of sugar nucleotides was reported in 1958, when Moffatt and Khorana269 prepared uridine 5 -(a-D-glucopyranosyl pyrophosphate) (5) in 59% yield from uridine 5 -phosphoramidate (58). Other examples of similar... 

Scheme 2.2.S.7 Synthesis of sugar phosphonic acids as potential enzyme inhibitors.

Total synthesis of sugars from non-carbohydrate precursors forms a link, perhaps the most prominent one, between carbohydrate and general organic chemistry. Many such syntheses have been undertaken, more in order to demonstrate the maturity and potency of stereocon-trolled, organic synthesis than to elaborate an alternative access to... 

The first, total synthesis of sugar-like compounds was performed as early as 1861 in that year, Butlerov2 reported the formation of methylenitan on treatment of aqueous formaldehyde with calcium hydroxide. The first, defined sugar derivative, DL-mannitol ( a-acrit ), was obtained by Emil Fischer and Tafel,3 and the first, optically active, totally synthetic sugars, D- and L-mannose and D- and L-fructose, were also prepared by Fischer.4... 

In the first half of this century, only a few papers concerning the total synthesis of sugars (mostly DL-tetroses) were published. A substantial increase in the number of papers since 1950 was the consequence of many important developments in stereospecific functionalization of organic compounds, in separation techniques, and in methods for structural determination. 

For the application of alkenes as precursors in the synthesis of carbohydrates, knowledge of their stereochemistry is essential. Fortunately, several alkenic compounds having a defined configuration of the double bond and proper functional groups are readily available, making them convenient substrates in the synthesis of sugars. 

The parent compounds of all pyranoses, the 2H- and 4H-pvrans (165 and 166), and their derivatives, are impractical as substrates for the synthesis of sugars. They are usually difficultly available and are rather unstable.60... 

In contrast, the dihydro derivatives of 165 and 166, namely 3,4-dihy-dro-2H-pyran (167) and 5,6-dihydro-2f/-pyran (168), and their simple derivatives, have found wide application in the synthesis of sugars of various types. 

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