Carbohydrates McM chapt 25

1
Carbohydrates (McM chapt 25)
Glucose C6H12O6 C6(H2O)6
D-shugars
Monosaccharides / Simple carbohydrates Can not
be hydrolyzed to simpler carbohydrates
2
Open and cyclic forms
3
Monosaccharides - Reactions (McM chapt 25.7)
Functional groups Alchohols, aldehydes/ketones,
hemiacetals
React like ROH
4
Glycosides in nature
DNA / RNA
Metabolism
More hydrophilic metabolite of RXH
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Glycyrrhizin Saponin from liquorice (lakris)
root expectorants (slimløsende) respir. tract
infect.
From microorganisms
6
Stereoselectivity in glycoside syntheses
7
The anomeric effect
Stereoselective synthesis of b-glycisides -
Koenigs Knorr react
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Reduction of carbonyl
Oxidative reactions
Reducing shugars Easily oxidized (most often
aldeh. - acid)
Tests (visual results) Not used in synthesis
(preparative scale)

• Tollens
• Fehling
• Benedict old diabetes (glucose) test

9
Ketoses as reducing shugars
Synthetically useful oxidations
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Chain Lengthening and Shortening
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Disaccharides (McM chapt 25.9)
Monosaccharides / Simple carbohydrates Can not
be hydrolyzed to simpler carbohydrates
Complex carbohydrates Disacch., polysacch. Can
be hydrol. to monosacch. (cleav. of acetal /
hemiacetal)
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Milk intolerance
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Polysaccharides (McM chapt 25.10)
Cellulose
Long chains (gt1000 monosachh.) H-bond between
chains Structural material - plants b-glycoside
link., not digested humans
Starch Amylose and amylopectin
Amylopectin ca 80
Amylose ca 20
Energy storage plants a-glycoside link., digested
humans
Glycogen amylopectin, larger, more
branches Energy storage animals
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Synthesis Di- and Polysaccharides

• Building from monosaccharides - Challenges
• Regioselectivity
• Stereoselectivity
• Stability

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Other carbohydrates (McM chapt 25.11-12)
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Aminoglycoside antibiotics
Lincomycin antibiotics
Glycoproteins / Glycopeptides
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Neuraminidase Inhibitors
Effect on influenza virus A and B(?) Inhib.
neuraminidase (enzyme that breaks bonds between
HA in newly HA in formed virus and host
cell) Prevents release of virus
HA Hemaglutinin, (glycoprotein) important for
bonding between influenza virus and host
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SN1
TS
Zanamivir Relenza
Oseltamivir Tamiflu