Embed Size (px)
DESCRIPTION
orgo problem sets
Citation preview
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
1
1. Give the major product of the following reactions. Please indicate stereochemistry where ever possible. Clearly indicate if a racemic mixture is formed. If no reaction occurs write the starting material that is being used for that step.
Cl H
N
HCl
MeO
C
N
OOH
O
H
O
O
OH
D
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
2
!
!
H
CH3
HH
H
OH
H
H
OH
OH
racemic
pent-2-yn-1-ol
(E)-hex-3-ene (3R,4R)-hexane-3,4-diol
OHH3C
racemic
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
3
2. Provide the reagents in correct order to achieve the following transformation.
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
4
A
A- 1. mCPBA / CH2Cl2; 2a. CH3MgBr / ether or CH3Li / ethe, 2b. NH4Cl (aq);3. PCC/ CH2Cl2
B
B- 1. mCPBA / CH2Cl2; 2a. CH3MgBr / ether or CH3Li / ethe, 2b. NH4Cl (aq);3. H2O/H2SO4, heat4a. O3 4b. (CH3)2S-DMS
you should not cleave the double bond first and then add GR to aldehyde and then oxidize the alcoholGR will add to both sides. You can use H2O/ Br2 followed by base NaOH to make epoxide instead of mCPBA
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
5
3. Show how you would synthesize 3-methyl-4-hepyn-3-ol starting with acetylene and any necessary additional reagents. Show products from each step.
4. A compound with MF: C13H22 on ozonolysis (O3 followed by Me2S) gave the following carbonyl compounds. Propose the structure of the starting compound.
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
6
5. Using curved arrows show detailed mechanism for reaction of lactones with excess of phenyl magnesium bromide.
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
7
6. Using curved arrows show detailed mechanism for reaction shown below.
B
H
HH
HNa
O
H
NaOR
O
H
BH3
HO
O
H
B O
H
OOH H
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
8
Provide reagents for the following transformation.
OR – HBr can work in step 2 since it is a sec alcohol and stereochemistry in not important (via SN1)
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
9
7. Give the major product of the following reactions. Please indicate stereochemistry where ever possible. Clearly indicate if a racemic mixture is formed. If no reaction occurs write the starting material that is being used for that step.
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
10
8. Retrosynthesis analysis compound is shown below. Show a forward synthesis of compound F.
9. Propose synthesis of compounds (A – B) shown below using the appropriate reagents and using the cyclohexene as the carbon building blocks shown below: Synthesize: A
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
11
B.
Step-1 Diels-Alder is not required- Start from cyclohexene for exam-1. 10. Give products from the sequence of reactions:
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
12
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
13
11.
Note Ketones are more reactive than esters also product indicates first attack is on ketone.
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
14
12. Retrosynthetic analysis. Show the precursors from which each compound can be derived following the disconnection shown.
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
15
13. Give the major product of the following reactions. Please indicate stereochemistry where ever possible. Please indicate “No Reaction” where appropriate. In the small box indicate “SP” for single product and “RM” for racemic mixture.
H
OH
H
OH
OH
diastereomers(not racemic)
achiral
OH
HOO
5-ethyl-5-hydroxyheptanoic acid
OH
HO
5-ethylheptane-1,5-diol
cyclopentylmethanol
achiral achiral
OH
OH
OH
OH
OH
diastereomersnot racemic mixture
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
16
14. What is the major organic product obtained from the following series of reactions? Draw arrows to show the products for the first step.
OH
CH3
achiral
CH3
1-methylcyclopent-1-ene
1-methylcyclopentan-1-ol
O
CH3
O
H
5-oxohexanalachiralachiral
15. Treatment of the aldehyde ester A with excess LiAlH4, followed by an aqueous acid quench, affords
Answer is IV
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
17
16. Show the detailed stepwise mechanism for the reaction shown below. Explain why A is the major product.
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
18
Provide a reasonable synthesis of 3-hexyn-1,6-diol using acetylene and ethylene oxide as the only sources of carbon atoms, using any other reagents as necessary.
------------------------------------------------------------------------------------------------------------
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
19
Indicate the reagents (or series of reagents) A through C necessary to effect each of the following transformations. Each letter A through C may represent more than one reagent. Note that any chiral product is racemic!
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
20
------------------------------------------------------------------------------------------------------------
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
21
Answer is D
Dr. Manashi Chatterjee Week-4-Recitation Chem 224
22
Answer is B
