Chem 215-216 HH W13 - Quiz 13!! (30 point including 10 bonus points) April 22, 2013 - This quiz has two pages. Name _____Key______

Lab: Mon; Tue; Wed; Fri (circle one that applies) GSI: April; Luke; Nathan; Zac (circle one that applies)

I (6 points) The known as L- is shown as an open-chain Fischer projection. Draw in the boxes below: (a) the corresponding form as the α- using a conformational representation, and (b) the corresponding form as the β-anomer using a Haworth projection formula.

(a) (b) L-altrose H O OH HO 1 OH O H OH 5 4 1 2 HOCH2 O 1 H HO 3 HO 5 OH 4 HO H HO 4 H OH OH CH OH HO 5 H 2 CH OH 3 6 2 α-pyranose: conformational representation β-furanose: Haworth projection 3

II. (4 points) For each of the following molecules, assign its anomeric configuration as α or β.

D (a) - (b) HO L-sugar HO OH O HO OH OCH3 H3C O OH OH HO Circle the one that applies: Circle the one that applies:

α- or β-anomer α- or β-anomer 1 1

(c) (d) SPh OH HO HO O H O CH2OH HO D-sugar OH OH HO D-sugar H CH2OH

Circle the one that applies: Circle the one that applies:

α- or β-anomer α- or β-anomer 1 1

215-216 HH W13 Quiz 13!! (April 22) – page 2

III. (13 points) Glycoside 1 is a new steroidal saponin isolated from the rhizomes of Polygonatum kinigianum, one of the original plants commonly known as Huang-jing in traditional Chinese medicine [Helv. Chhem. Acta 2010, 93, 1086]. Treatment of the glycoside, 1, with the enzyme β−glycosidase provides trisaccharide 2. Answer the following questions about this glycoside 1 and trisaccharide 2.

O H

O HO O HO H H HO OH O O HO O O HO HO O O C O O α O β enzyme HO A HO OH O H OH α HO O H HO HO B OH 1 HO 2 OH (1) (3 points) Label each of the glycosidic bonds in glycoside 1 using a small arrow ( → ).

(2) (3 points) Classify each glycosidic linkage in 1 as α or β right next to each of the arrows you have shown.

(3) (1 points) How many D-sugar units does trisaccharide 2 have? (circle one) 0 1 2 3

(4) (1 points) Is the hemi-acetal OH in trisaccharide 2 α or β? (circle one) α β (5) (1 points) Is trisaccharide 2 a ? (circle one) Yes No

(6) (4 points) Describe the linkages between the following sugar units [e.g., α(1 -> 6)]:

For A and C: α (1 − >3) For B and C: α(1−>2)

IV (7 points) Draw in the boxes below the structures of the expected reaction intermediate/product. Draw the structures in a chair form.

anomeric mixture O O CH H3C O 3 OCH3 OCH CH3O 3

HBr anomeric effect!

CH2Cl2 Br (solvent) NaSCH2CH3 H C SCH CH H3C O 3 O 2 3 OCH3 OCH3 SN2! OCH OCH3 CH3O 3 CH3O

4 3 + NaBr + H3CC(=O)OH