NE224 Lecture Notes - Lecture 13: Stereocenter, Stereochemistry, Polysaccharide
9 Oct 2014
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Document Summary
Other derivatives monosaccharides glycosidic bonds oligosaccharides disaccharides polysaccharides: glycoproteins glycolipids storage polysaccharides: starch and glycogen structural polysaccharides: cellulose and chitin. Emil fischer, d- and l- : d- is common form in nature. Glyceraldehyde and dihydroxyacetone are the simplest sugars (trioses) D-or l- : designation determined by stereochemistry at chiral carbon that is furthest away from carbonyl: in linear fischer representation, final chiral c (c*) with. Many stereocenters many isomers enantiomers: mirror images diastereomers: stereoisomers that differ at 1 or more chiral centres and are not enantiomers (so different mpt etc) epimers: differ at only one stereocenter. D-erythrose and d-threose are epimers at c2 (also diastereomers) Common sugars are boxed addition of 1 c adds a stereo centre. Figure 11-3 to form hemiacetals and (b) ketones to form hemiketals. Intramolecular nucleophilic attack by hydroxyl group at the carbonyl group to make cyclic form of sugar.
