Aldoses nomenclature

Aldoses with at least three carbons and ketoses with at least four carbons contain chiral centers (Chapter 4). The nomenclature for such molecules must specify the configuration about each asymmetric center, and drawings of these molecules must be based on a system that clearly specifies these configurations. 

The parent that includes the functional group most preferred by general principles of organic nomenclature [13,14], If there is a choice, it is made on the basis of the greatest number of occurrences of the most preferred functional group. Thus aldaric acid > uronic acid/ketoaldonic acid/aldonic acid > dialdose > ketoal-dose/aldose > diketose > ketose. 

The names of the individual compounds of this type are formed by replacing (a) the -ose of the systematic or trivial name of the aldose by -uronic acid , (b) the -oside of the name of the glycoside by -osiduronic acid or (c) the -osyl of the name of the glycosyl group by -osy luronic acid . The carbon atom of the (potential) aldehydic carbonyl group (not that of the carboxy group as in normal systematic nomenclature [13,14]) is numbered 1 (see 2-Carb-2.1, note 1). 

The carbonyl group in glucose and ribose is an aldehyde such compounds are termed aldoses. Fructose, by contrast, has a ketone group and is therefore classified as a ketose. Glucose could also be termed an aldohexose and fructose a ketohexose, whereas ribose would be an aldopentose, names which indicate both the number of carbons and the nature of the carbonyl group. Another aspeet of nomenclature is the use of the suffix -ulose to indicate a ketose. Fructose could thus be referred to as a hexulose, though we are more likely to see this suffix in the names of specific sugars, e.g. ribulose is a ketose isomer of the aldose ribose. 

PHYSICAL ORGANIC CHEMISTRY NOMENCLATURE ALDEHYDE DEHYDROGENASE ALDEHYDE HYDRATION ALDEHYDE OXIDASE ALDEHYDE OXIDOREDUCTASE ALDOSE REDUCTASE Aldehyde reduction to alcohols, BOROHYDRIDE REDUCTION ALDOLASE Aldolase reduction,... 

Trivial names are common in carbohydrate nomenclature. Fifteen of them form the basis of the systematic nomenclature. They are assigned to the simple aldoses (polyhydroxyaldehydes), from triose to hexoses. 

Some of the key reactions in carbohydrate chemistry involve oxidation of aldoses to carboxylic acids. You will encounter some of these if you work Exercise 20-1. There is a simple nomenclature system for these acids. In abbreviated notation, the products of oxidation at Cl, C6, or both are called ... 

In 1927, Bertrand ( ) presented a proposal by H. Hfrissey and M. Bridel (3) suggesting that only the terminations -ose and -oside be retained of the words glucose and glucosides used as generic terms. The Warsaw conference adopted this designation of oses for simple sugars. The contraction was a simple one and made it possible to return easily to such customary nomenclature as aldoses, ketoses, pentoses, and hexoses. 

The ketoses are classified as 2-ketoses, 3-ketoses, etc., following the carbonyl position on the chain. The 2 of 2-ketoses, a common natural structure, can be removed. The suffix ose is replaced by ulose in the parent name. Likewise, fructose is a 2-hexulose, or more simply, a hexulose. For the complete name, it is preceded by the configuration descriptor. The systematic name of fructose 4.37 would be D-araZ>Z o-2-hexulose. In the case of 2-ketoses, there is no possible ambiguity for the configuration of pyranoses and furanoses. The nomenclature is copied from that of aldoses as, for example, /3-D-fructopyranose 4.38. Methyl glycoside 4.39 of sialic acid is called methyl 5-acetamido-3,5-dideoxy-D-gZycera-a -D-gaZacfo-2-nonulopyranosidonic acid. 

Ketoses have one asymmetric centre fewer than the corresponding aldoses, and therefore according to lUPAC nomenclature should be named from the... 

The nomenclature of carbohydrates usually includes the suffix -ose. Monosaccharides may also be identified according to the nature of the carbonyl functional group (aldose or ketose), the number of carbons in the molecule (tri-, tetr-, pent- ose) or a combination of these two. Monosaccharides also have common names such as ribose, glucose, galactose, and fructose (four of the most common monosaccharides found in nature). 

A pair of diastereomeric aldoses that differ only in the configuration about the second chiral carbon are called epimers. The more important nomenclature used in chiral chemistry is summarized in figure 1.9. 

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