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Exam 3 – CH 0320
NAME ___________________________________ Good luck! Page 2 1. Give an example for each description. Use Fisher, Haworth, or conformational
a) An aldopentose: b) A ketohexose: c) Methyl β-D-ribopyranoside: d) L-xylose: e) Xylitol: f) Any reducing sugar: Page 3 2. Provide products for each of the following transformations. HO
CH2 OH HO
HO a CHO
CH2 OH b Br2 /H2 O HCN O
O Mannich O
d e f CH3 NH2 /H+ H HS
CH2 OH CHO
CH2 OH SH
NHNH2 2 equivalents HNO3 /H2 O C7 H13 NO Page 4
3. For each of the following transformations, provide mechanisms. (8 points each)
a) Show each bond forming step, including deprotonations and protonations.
b) Show correct formal charges on each atom that is not neutral.
c) In base catalyzed reactions, show an appropriate source for protonation. (for
example, H2 O or HOR). a. OH HO HO OH + HOCH 3/H HO O H3 CO O 3 (continued – Show the mechanism). Page 5
1) MeI (excess)
2) Ag2 O/H2 O/heat
H (H3 C)2 N Page 6 4. Show you would prepare glucose from a pentose using the Kiliani-Fisher method. Show
all reagents. Choose the appropriate starting material. Show all intermediates, but it is
not necessary to show mechanism. Page 7
5. Devise a preparation of the following amine using the reductive amination conditions. H N CH3 Page 8 6. a) Draw a hexose that will give an optically active product after treatment with nitric acid. b) Draw a pentose that will afford an optically inactive alditol. 7. Ruff degradation of Aldose A affords a pentose. The same pentose is formed through a
Kiliani-Fisher synthesis beginning with D-threose. Treatment of Aldose A with NaBH4
affords an achiral product. What is Aldose A? Show your reasoning. ...
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- Spring '09