Chiral compounds glyceraldehyde

It was then possible, by unambiguous chemical interconversion procedures or by physical property comparisons, to relate many compounds having one or more chiral carbons to either of the enantiomers of glyceraldehyde. This enabled a number of chiral compounds to be designated as belonging to the d- or l-... 

At the time the d and l system of relative configurations was introduced, chemists could not determine the absolute configurations of chiral compounds. They decided to draw the d series with the glyceraldehyde OH group on the right, and the l series with it on the left. This guess later proved to be correct, so it was not necessary to revise all the old structures. 

Glyceraldehyde is one of the simplest chiral compounds in nature. Because of this, chemists took it as the standard against which the configurations of other compounds could be compared. The two enantiomers of glyceraldehyde were given the labels D (for dextro— because it was the (+)-enantiomer) and l (for laevo—because it was the (-)-enantiomer). Any enantio-merically pure compound that could be related, by a series of chemical degradations and transformations, to D-(+)-glyceraldehyde was labelled D, and any compound that could be... 

The simplest monosaccharides are the compounds glyceraldehyde and dihydroxyacetone (see the following structures). Of these two compounds, only glyceraldehyde contains a chirality center. 

Throughout this chapter we have written three-dimensional structures for particular stereoisomers and it is important to know how these have been determined. How, for example, do we know that (+)-alanine has the absolute configuration (1) and not (2) The answer is that until 1951 this was not known and the three-dimensional structure of stereoisomers was shown according to a convention introduced in the last century by Emil Fischer. According to this convention it was assumed that (+)-glyceraldehyde had the three-dimensional structure (67). Once this assumption had been made a self-consistent system of conventional representations could be applied to many other chiral compounds by chemical correlation with (67). In 1951 a group led by Bijvoet in Utrecht determined the absolute configuration of the... 

The synthesis starts with mannitol, which is a symmetrical but chiral compound (note the C2-axis of symmetry). The bis-ketal is oxidatively cleaved to give two moles of a widely used chiral building block, the ketal of (+)-glyceraldehyde (5). Reaction of (5) with the anion of methyl oleate gives hydroxyester (6), hydroxyl protection... 

The other isomer was called L-glyceraldehyde. All chiral compounds that could be converted into D-(+)-glyceraldehyde by reactions that did not affect the configuration at the stereocenter were assigned the d configuration, and their mirror... 

Glyceraldehyde can be considered to be the simplest chiral carbohydrate It is an aldotriose and because it contains one chirality center exists in two stereoisomeric forms the D and l enantiomers Moving up the scale m complexity next come the aldotetroses Examining their structures illustrates the application of the Fischer system to compounds that contain more than one chirality center... 

I-Oialkoxy carbonyl compounds are a special class of chiral alkoxy carbonyl compounds because they combine the structural features, and, therefore, also the stereochemical behavior, of 7-alkoxy and /i-alkoxy carbonyl compounds. Prediction of the stereochemical outcome of nucleophilic additions to these substrates is very difficult and often impossible. As exemplified with isopropylidene glyceraldehyde (Table 15), one of the most widely investigated a,/J-di-alkoxy carbonyl compoundsI0S, the predominant formation of the syn-diastereomer 2 may be attributed to the formation of the a-chelate 1 A. The opposite stereochemistry can be rationalized by assuming the Felkin-Anh-type transition state IB. Formation of the /(-chelate 1C, which stabilizes the Felkin-Anh transition state, also leads to the predominant formation of the atm -diastereomeric reaction product. 

Conversion of the unknown to, or formation of the unknown from, a compound of known configuration without disturbing the chiral center. See the glyceraldehyde-glyceric acid example above (p. 138). Since the chiral... 

Reactions of nitro compounds with chiral imines have only recently been described. Either chiral 1-phenylethylamine (auxiliary) or the glyceraldehyde acetonide aldehyde was used as the chiral precursors of the imines 66 and 68, which reacted with 3-mesyloxynitropropane to give the 3-nitropyrrolidines dl)-67 and 69, respectively, with good diastereoselectivity. In fact, both products were obtained (almost) exclusively as trans diastereomers with high level of asymmetric induction, but the configurations of the newly formed stereocenters were not determined [44] (Scheme 13). N-Boc imines can be formed... 

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