The D Aldose Family CHO H-OH CH.OH D-(+)-glyceraldehyde CHO CHO H-OH HO-H H-OH H-OH CH,OH CH,OH D-(-)-erythrose D-(-)-threose CHO CHO CHO CHO H -OH HO- H H-OH HO-H H -OH H--OH HOH HO-H H--OH H-OH H-OH H-OH CHOH CHOH CH,OH CH,OH D-(-)-ribose D-(-)-arabinose D-(+)-xylose D-(-)-lyxose CHO CHO CHO CHO CHO CHO CHO CHO H OH HO- H H 一OH HO- -H H- 一OH HO- H H -OH HOH H -OH H一OH HO-H HO- 一H H 一OH H -OH HO- H HO一H H -OH H 一OH H一OH H 一OH HO- H HO- 一H HO -H HO-H H-OH H一OH H-OH H-OH H-OH H-OH H一OH H-OH CH,OH CH.OH CHOH CH,OH CHOH CH,OH CH,OH CH,OH D-(+)-allose D-(+)-altrose D-(+)-glucose D-(+)-mannose D-(-)-gulose D-(-)-idose D-(+)-galactose D-(+)-talose Copyright2005 Pearson Prentice Hall.Inc. 6
Chapter 23 6 The D Aldose Family =>
Erythro and Threo Terms used for diastereomers with two adjacent chiral C's,without symmetric ends. For symmetric molecules,use meso or d,1. CH2CH3 CH2CH3 COOH COOH H Br Br H H OH H OH H Br H Br H OH HO H CH3 CH3 COOH COOH erythro threo meso (±)or(d,) 2,3-dibromopentane tartaric acid => Chapter 23 7
Chapter 23 7 Erythro and Threo • Terms used for diastereomers with two adjacent chiral C’s, without symmetric ends. • For symmetric molecules, use meso or d,l. =>
Epimers Sugars that differ only in their stereochemistry at a single carbon. CHO C2 epimers CHO CHO H OH H-2 OH HO -H HO3 -H C4 epimers HO-H H -OH H--OH HO4H H-5-OH H-5 OH H -OH CH,OH CH,OH CH,OH D-mannose D-glucose D-galactose => Chapter 23 8
Chapter 23 8 Epimers Sugars that differ only in their stereochemistry at a single carbon. =>
Cyclic Structure for Glucoses Glucose cyclic hemiacetal formed by reaction of -CHO with -OH on C5. CHO H3/ -OH -H CHOH H CHOH H H -O OH OH CH OH O H O+ H H OH H Hy+H 一OH H 4KòH HO 2 HO 3 H CH,OH OH H OH OH Fischer projection on right side C6 rotated up Haworth projection H 6 H CHOH CI is the only carbon atom CHOH HO bonded to 2 oxygens HO -0 HO H HO、 H 3 OH OH 0 OH TH H OH chair conformation (all substituents equatorial) chair conformation (OH on Cl axial) Copyright 2005 Pearson Prentice Hall,Inc. Chapter 23 D-glucopyranose 9
Chapter 23 9 Cyclic Structure for Glucose Glucose cyclic hemiacetal formed by reaction of -CHO with -OH on C5. => D-glucopyranose
Cyclic Structure for Fructoses Cyclic hemiacetal formed by reaction of C=O at C2 with -OH at C5. CH2OH 2C=0 H HO3-H HO-CH2Q: -H HOCH2O OH HO H 5K HO 一OH H4 CH2OH H43 CH2OH H-5-OH OH H OH H cyclic form 6CHOH D-fructose D-fructofuranose Copyright 2005 Pearson Prentice Hall,Inc. => Chapter 23 10
Chapter 23 10 Cyclic Structure for Fructose Cyclic hemiacetal formed by reaction of C=O at C2 with -OH at C5. => D-fructofuranose