Fischer projections, and

Fischer projections and d-l notation have proved to be so helpful m representing carbohydrate stereochemistry that the chemical and biochemical literature is replete with their use To read that literature you need to be acquainted with these devices as well as the more modern Cahn-Ingold-Prelog R S system... 

The aldotetroses are the four stereoisomers of 2 3 4 trihydroxybutanal Fischer pro jections are constructed by orienting the molecule m an eclipsed conformation with the aldehyde group at the top The four carbon atoms define the mam chain of the Fischer projection and are arranged vertically Horizontal bonds are directed outward vertical bonds back... 

Fischer projections and d-l notation are commonly used to describe car bohydrate stereochemistry The standards are the enantiomers of glycer aldehyde... 

Problem 25.4 Redraw the following molecule as a Fischer projection, and assign R or 5 configuration to the chirality center (yellow-green = Cl) ... 

Fischer projections and, 977-978 glycosides and, 989-990 l- 4 links in, 997-998 origin of name. 973 photosynthesis of, 973-974 see also Aldose, Monosaccharide vaccines from, 1004-1005 Carbon, ground-state electron configuration of, 6... 

Fischer projections and, 977-978 glycosides of, 989-990 hemiacetals of, 984-986 osazones from, 1013 oxidation of, 992-994 phosphorylation of, 991 reaction with acetic anhydride, 988... 

Fig. 1. Higher-order sugars L-g/yceroD-manno-Heptose (1, open-chain and 2, a-pyranose) and A -acetylneurami ilic acid (3, a-pyranose form). Structures 4-8 depict D-glucose (4) as its open-chain Fischer projection, and as the a-oxetose (5), a-furanose (6), a-pyranose (7), and a-septanose (8) ring forms.

Problem 6.56 (a) Br, is added to (S)-H2C=CHCHBrCH,. Give Fischer projections and R,S designations for the products. Are the products optically active (b) Repeat (a) with HBr. ... 

Name the alternating head-to-tail copolymer of styrene and carbon monoxide. Draw adapted Fischer projections and planar zigzag projections for both stereoisomers of this copolymer. 

If this model were compressed into two-dimensional space, we would get the projection shown in Fig. 27.6c. This is termed a Fischer projection and is named after a pioneer in stereochemistry, Emile Fischer. The Fischer projection has the following requirements ... 

In general, if you have a Fischer projection and rotate it in the plane of the paper by 180°, the resulting projection is of the same system. Test this assumption by taking the Fischer projection in Fig. 27.6c, rotating it in the plane of the paper by 180°, and comparing it to the drawing you did for no. 11a. 

The Fischer projection is a convenient way of showing the configurations of the linear forms of monosaccharides. This convention depicts the concepts of stereochemistry established by Jacobus Henricus van t Hoff and Joseph Achille Le Bel in a simplified form. While these abbreviated structural formulas are simple to write and easy to visualize, there are some guidelines that should be taken into account when converting a three-dimensional structure into a Fischer projection and in its manipulation (Fig. 1.2) ... 

Q Draw and identify the structures of glucose, its anomers, and its epimers, as Fischer projections and as chair conformations. 

Erythrose is the aldotetrose with the OH groups of its two asymmetric carbons situated on the same side of the Fischer projection, and threose is the diastereomer with the OH groups on opposite sides of the Fischer projection. These names have evolved into a shorthand way of naming diastereomers with two adjacent asymmetric carbon atoms. A diastereomer is called erythro if its Fischer projection shows similar groups on the same side of the molecule. It is called threo if similar groups are on opposite sides of the Fischer projection. 

Learn to draw glucose, both in the Fischer projection and in the chair conformation (all substituents equatorial). Draw other pyranoses by noticing the differences from glucose and changing the glucose structure as needed. 

Draw the Fischer projections and the chair conformations of the anomers and epimers of glucose from memory. Identify and name these sugars based on how they differ from the structure of glucose. Problems 23-52 and 53... 

Draw the skeleton of the Fischer projection and add the -CHO and -CH2OH groups to the top and bottom, respectively. Look at each carbon from the direction in which the -H and -OH point out of the page, and draw what you see on the Fischer projection. 

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