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Converting Fischer structures to Haworth and chair forms. Start with the Fischer (Rosanoff) structure. D-glucose. 5. Form the pyranose ring. D: CH 2 OH at C5 goes up L: CH 2 OH at C5 goes down. This is a D-sugar. Determine alpha or beta.
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5 Form the pyranose ring • D: CH2OH at C5 goes up • L: CH2OH at C5 goes down
Determine alpha or beta • If OH at C1 is on the same side of the ring as the CH2OH group, the sugar is beta • If the OH at C1 is on the opposite side of the ring as the CH2OH group, the sugar is alpha • Let’s make our example beta
Same side The beta anomer
What remains to be done? • We need to know the configuration of the OH groups at carbons 2, 3, and 4 • How do we do this? • Go back to the Fischer (Rosanoff) projection • Then lay it over on it’s side to the right
Fischer structure D-glucose
Place remaining OH groups • Put the remaining OH groups on the Haworth ring at C2, C3, and C4 in the same orientation (up or down) as they are in the leaned over Fischer/Rosanoff structure