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Unformatted text preview: NAME: CEM 850 Exam-2
October 25, 2003 This exam consists of 15 pages. Be sure to write your name on all pages of the exam. Please write legibly and draw all structures clearly. Good luck. 1. For the following dipoles: (a) (3 pts) Circle the dipole that you predict would be the most stable. (b) (3 pts) Provide an explanation for why you think the identified dipole is the most stable: 2. (3 pts) Rank the following underlined protons in order of increasing acidity (decreasing pKa).
O HCN H3C OH H3C H O O CH3 H3C O CH3 H3C H O O OCH3 H O H A B C D E F High pKa
1 Low pKa NAME: 3. For the following reaction of 1,2,3,3-tetrachlorocylopropene:
Cl Cl SbCl5 Cl Cl (a) (2 pts) How many electrons occupy the HOMO in the product? (b) (4 pts) Provide an explanation for your answer using a Frost circle depiction of energy levels. 4. For the following reaction:
DCl Cl D D Cl D Cl (a) (2 pts) Circle which products are formed in the reaction. (b) (2 pts) Which product is formed in the highest yield? (draw in the space provided below) 2 NAME: (c) (2 pts) Provide an explanation to your answer to question 4b. 5. (6 pts) Provide a detailed mechanism for the following reaction that explains ALL of the products formed in the following reaction:
N + N O O heat O + SO2 + N2 S O 3 NAME: 6. (6 pts) Provide a detailed mechanism for the following conversion:
H3C Cl CH3 CH3 AlCl3 CH3 H3C CH3 4 NAME: 7. (6 pts) Provide a detailed mechanism for the Moffatt oxidation of an alcohol.
N C N RCH2OH DMSO / H+ (cat.) 5 NAME: 8. (6 pts) Provide the products and a detailed mechanism for the ozonolysis of the following olefin with reductive workup. 1. O3 / CH2Cl2 2. Zn 6 NAME: 9. (1 pts per box) Fill in the boxes, and provide stereochemistry if relevant. H2 1. OsO4 2. NaHSO3 Lindlar's Cat. O O H3C H3C Cl OH CH3OH KMnO4, OH 0o C K OtBu CHCl3 HCl Cl HIO4 O O + H 7 NAME: 10. (5 pts) Provide reasonable syntheses for the following molecule.
O HO OH steps O 8 NAME: 11. Consider the Following reaction:
O O KCN / HCl
NC (a) (3 pts) Briefly state why in the following reaction the 1,4 addition product is obtained instead of the 1,2 addition product. (b) (2 pts) Which addition (i.e. 1,4 addition or 1,2 addition) is the kinetic process and which is the thermodynamic process. 12. Treatment of compound 1 with an aqueous solution of bromine and sodium hydroxide affords after acidification, pivalic acid (2) and bromoform.
1. NaOH/Br2/H2O 1 2. H2O/H3O+ t-BuCO2H
2 + HCBr3 (a) (2 pts) What is the structure of 1? (b) (2 pts) How many equivalents of NaOH are necessary for this reaction? 9 NAME: 13. Consider the reactions shown below:
O 1. t-BuOK, t-BuOH, 25 °C 2. H2O 4 3 1. LDA, THF, -78°C 2. heat 3. H2O 5 O (a) (2 pts) provide a reasonable structure for 3? (b) (2 pts) Draw both the thermodynamic and kinetic enolates of 4? (c) (2 pts) Draw the expected product of the reaction of 5 with NaOD/D2O. 10 NAME: 14. Provide the reagents/conditions that would enable the following transformations: (a) (5 pts)
OH HO O O OH 11 NAME: (b) (5 pts)
Br O 12 NAME: (c) (5 pts)
HO CH3 OH 13 NAME: 15. (6 pts) Provide a detailed arrow pushing mechanism for the following reaction:
HSn(Bu)3 CH3CH2C CH AIBN, D CH3CH2 H C C H Sn(Bu)3 14 NAME: 16. (2 pts per box) Fill in the boxes, and provide stereochemistry if relevant. OH 1. CrO3 / H2SO4 2. SOCl2 3. AlCl3 O O 1. DIBAL, cold 2. 3. H2 / Pt 4.
O NH2 O O Br 1. t-BuOK 2. mCPBA 3. CH3MgBr 4. CrO3 / H2SO4 / H2O Na 1. BH3 2. H2O2/HO NH3(l) Bonus Question: (2 pts) Next week, Bob Grubbs will return to MSU as our 23rd Dow/Karabatsos Lecturer. Where was Grubbs born? a. Elephant Butt, New Mexico b. Fish Kill, New York c. Moose Jaw, Ontario d. Possum Trot, Kentucky e. Toad Suck, Arkansas 15 ...
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