Fisher-chair(not class notes)

Fisher-chair(not class notes) - O OH CH 2 OH OH CH 2 OH O...

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Methods of Converting Fischer Projections of Sugars to Haworth Projections Three methods of generating Haworth Projections from Fischer projections follow. The first is similar to the one presented in the book on p. 533 but makes placement of the –OH’s simpler. Use whichever method you find easiest to remember. Let’s consider two sugars, one an aldohexose, the other an aldopentose. Fischer projections are shown below. One the following two pages, we’ll generate Haworth projections of each. Recall the carbon with the star (*) next to it is the one that determines if the sugar is a D-sugar or an L-sugar. CHO OH OH HO HO CH 2 OH CHO OH OH CH 2 OH OH * *
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Method 1 1) Draw the basic structure for the sugar. O O 2) If the sugar is a D-sugar place a –CH 2 OH above the ring on the carbon to the left of the oxygen, for an L-sugar place it below the ring. O OH OH O -sugar -sugar 3) For an -sugar place an –OH below the ring on the carbon to the right of the ring oxygen, for an -sugar place the –OH above the ring.
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Unformatted text preview: O OH CH 2 OH OH CH 2 OH O L--sugar D--sugar 4) Finally, OH groups on the right go below the ring and those on the left above, using the CH 2 OH group as the reference point for both projections. O OH H H OH H OH OH H H CH 2 OH H OH H CH 2 OH H OH OH H O L--sugar D--sugar Method 2 This method involves memorizing both the Fischer and Haworth projections of glucose, then determining all other structures relative to it. First produce the two structures of -D-glucose. CHO OH HO OH OH CH 2 OH O OH OH OH OH CH 2 OH-D-glucose If you remember that the CH 2 OH group is up, then all you have to do is recall that the OH groups follow an alternating pattern from it. You then compare the position of the OH groups on the Fischer projection of the sugar you are interested in with that of glucose to place the OH groups. Those on the same side go in the same position, those on the opposite side go in the opposite position....
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Fisher-chair(not class notes) - O OH CH 2 OH OH CH 2 OH O...

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