Oxidations & Reductions.
Section-A: Each question carries 5 marks.
1. Explain the mechanism involved in Swern Oxidation by using suitable examples. 2. Write the structures of the products of the following reactions by giving suitable mechanism.
a) Cis-2-butene + OsO4 (cat), NMO, acetone-----?
b) Cis-1,2-dialkyl ethane + I2/CH3COOAg(dry) + saponification -----? 3. Write about Oppenauer Oxidation with mechanism.
4. Write about BH3 Reductions & write the mechanism. 5. Give the product & mechanism of their formation for the following reaction:
6. Give the products & mechanism of their formation of the following reactions.
7. How is Manganese IV oxide prepared? Describe its use for the oxidation of alcohols to carbonyl compounds. 8. How is DIBAL prepared? Describe its uses in reductions. 9. Write short notes on Swern oxidation. 10. Write short notes on oxidation with CAN reagent. 11. Write a note on hydroboration and the regiochemistry involved in it. 12. Write the structure of the product & explain its formation. 13. Write the structure of the products in the following reaction & explain their formation.
14. Explain briefly the use of homogenous catalytic reductions with two suitable examples. 15. Which products are formed in the following reactions? How are they formed?
i) Ph-CH2-CH3 + DDQ
ii) Ar-NH2 + NaNO2/HCl + Bu3SnH 16. Discuss the mechanism of Birch Reduction of anisole & benzaldehyde. 17. What are the synthetic applications of tri-n-butyl tin hydride? 18. Explain the mechanism of hydrogenation with Wilkinson’s catalyst. 19. Write a note on Oppenauer oxidation.
20. Write a note on Ag2CO3 as oxidizing agent. 21. Write a note on Chromium (VI) as oxidizing agent. 22. Write about Oxidative cleavage of 1,2-diols by periodic acid. 23. Write the mechanism for the following reaction.
24. Predict the product and the mechanism for the following reaction.
25. Write the structure or chemical composition of the following reagents:
a. Jones Reagent b. Collins Reagent c. PDC d. PCC
e. Fetizon’s Reagent
26. Write the mechanism for the following reaction and also predict the product.
27. Write a note on DMP & IBX reagents.
28. Write the structures of the following reagents and explain one application.
a. TEMPO b. TPAP
29. Write a note on the modifications of Lithium aluminium hydride.
30. Write a note on the modifications of Sodium boro hydride.
31. Write a note on Hydrogenolysis
32. Write the differences between Homogenous & Heterogenous Reduction
33. Write a note on Diimide Reduction with mechanism & example.
34. Predict the product for the following reaction with mechanism.
35. Predict the product for the following reaction with mechanism.
36. Write a note on Clemmensons reduction.
37. Write about LiAlH4 Reduction.
38. Complete the following reaction with mechanism by predicting the product.
39. Predict the products for the following reactions.
40. Write the reduction properties of BH3 by giving examples
41. Write the reduction properties of AlH3 by giving examples
Section-B: each question carries 10 marks.
1. a. Explain the various steps involved in the oxidation of allylic & benzylic C-H
bonds by using NBS & DDQ.
b.What is Birch reduction? Give examples of the reactions.
2. a. Explain Clemmenson reduction by giving an example.
b. Sketch the mechanism involved in Prevost oxidation.
3. a. Write about Swern oxidation with suitable reactions & mechanism.
b. Write about NaBH4 reduction with suitable mechanism. 4. a. Write about Wolff-Kishner reduction with mechanism.
b. Write about SeO2 with detailed mechanism & examples. 5.a. Predict the products in the following reactions & give the suitable mechanism.
b.What happens when the following reactant is treated with LTA in C6H6 at 30oC & give the mechanism for the product formation.
6.a. Describe the use of the following reagents in organic synthesis.
i. LTA ii. DMP b. Give the mechanism along with synthetic importance of the following
reductions.
i. Birch reduction ii. Wilkinson reduction.
7. a. Write short notes on the following:
i. Swern oxidation ii. Oxidation with CAN
b. Give the mechanism along with synthetic importance of the following
reductions.
i. Di-imide ii. DIBAL-H
8.a. Explain the conversion of ketones into esters using periodic acid.
b. Mention briefly the applications of Baeyer Villiger oxidation.
9.a. Explain in detail how metals & liquid ammonia are useful in the reduction of
organic substrates.
b. Give mechanism of reduction of carbonyl compounds using LiAlH4 & NaBH4 10.a. Predict the products & mechanism involved in the following reactions.
o i. Ph-CH=CH-CH3 + SeO2 + AcOH / 140 C----- ?
ii. D (+) Glucose + HIO4 ------? b. Predict the products & mechanism involved in the following reactions.
11.a. Explain birch reduction with an example.
b. Ph-CH=CH-CHO + LiAlH4------? Write the structure of the product in the above reaction & explain its formation.
12. a. 3R2CHOH + 2H2CrO4 ------? What are the products in the above reaction? How are they formed?
b. Explain diimide reduction.
13.a. Explain the heterogenous catalytic reductions with suitable examples.
b. Predict the products of the following reactions & write the mechanism
involved.
14.a. Compare Prevost & Woodward Oxidations.
b. Explain the mechanism of benzylic oxidation with NBS.
15. a. Discuss the mechanism of Swern oxidation of a primary allylic alcohol.
b. With suitable examples , explain the regioselectivity & syn addition with
boron hydrides. Discuss the mechanism of hydroboration- oxidation.
16. a. Discuss the mechanism of Swern oxidation of a primary allylic alcohol.
b. With suitable examples, explain the regioselectivity & syn addition with
boron hydrides.Discuss the mechanism of hydroboration.
17.a. Write the mechanism of the oxidation of tetralin with DDQ. b. What are the products in the periodic oxidation of methyl-D-
glucopyranoside. Give the mechanism.
18.a. Predict major & minor products formed in the following reactions. Give
reasons & explain the mechanism involved.
b. Write a note on the following reagents:
i. IBX ii. TEMPO
19.a. Using saw-horse formulae write the products formed when cis & trans – 2 butenes are subjected to homogenous catalytic hydrogenation separately.
b. Write short notes on the following reagents:
i. TPAP ii. CAN
20.a. Give an account of oxidations with periodic acid.
b. Write the reduction properties of DIBAL.
21.a. Discuss with suitable examples the mechanism & stereochemistry of products formed in a homogenous hydrogenation using Wilkinson’s catalyst.
b. Write a note on Chromium salts as oxidizing agents.
22.a. Give an account of reduction reactions of LAH.
b. Explain the reduction properties of Ketone with AlH3 23.a. Explain the reduction of acetone by boron hydride.
b. Describe the stereochemistry involved in the Prevost hydroxylation.
24.a. Discuss the applications of the following reagents. Provide the mechanism.
i. Dissolving metal reductions. Ii. Openauer oxidation
25. Predict the products formed in the following reactions. Give mechanism.
26. a. Discuss the use of the following reagents with mechanism.
i. LTA ii. Homogenous catalytic reduction
b. Predict the products formed in the following reactions. Give mechanism.
27. a. Explain the mechanism of addition of diimide to cis-2-butene.
b.Write the products of following reaction with suitable mechanism.
28.a. Explain the following with suitable mechanism.
b. Write notes on metal-hydride reductions.
29.a. Write a note on the synthetic utility of the following:
i. LTA ii. SeO2 b. Predict the product with stereochemistry & write suitable mechanism.
30.a. Differentiate the reactivity of LAH & AlH3 in the reduction of carbonyl compounds.
b. Describe the utility of periodic acid in the oxidative cleavage of diols.
31.a. Discuss the following with proper mechanism.
i. Reduction of epoxides by LiAlH4 & BH3
ii. Cis-hydroxylation of olefins.
b. Predict the products formed in the following reactions with mechanism.
32.a. Discuss the following with suitable mechanism.
i. Oxidation of alcohols by Cr+6
ii. Reduction by Na-Liq NH3 b. Predict the products formed in the following reactions. Provide the mechanism.
33.a. Suggest suitable mechanism for the following reaction.
b. Discuss the mechanism of heterogenous catalytic reduction.
34. a. Write a note on diimide reduction.
b. Sketch the mechanism of homogenous catalytic hydrogenation.
35.a. Suggest the reagents with suitable mechanism in the following conversions.
b. Write anote on Diimide reduction.
36. a. Differentiate the reactivity of LiAlH4 & AlH3 in the reduction of carbonyl compounds.
b. Describe the utility of HIO4 in the oxidative cleavage of diols.
37.a. Write about reduction of epoxides by LAH & BH3 b. Explain cis-hydroxylation of olefins.
38.a. Explain the use of SeO2 in organic synthesis. b. Write a note on use of tri-n-butyl tin hydride.
39. a. What are the synthetic applications of DDQ & NBS.
b. Illustrate the synthetic utility of the following methods with examples. i. Oppenauer oxidation ii. Prevost oxidation.
40. a. Predict the product with stereochemistry & give suitable mechanism.
b. Write a note on Woodward Oxidation.
41.a.Write about MnO2 Oxidation with example of reaction with mechanism b. Write about the following reagents with mechanism & examples.
i. Ag2CO3 ii. DMP reagent 42.a. Write short notes on tri-n-butyl tin hydride.
b.Write about Red-Aluminium reductions.
43.a.Write about DIBAL Reductions
b. Write about NaCNBH3, Selectride & Superhydride with examples.
PROTECTING GROUPS
SECTION A
Each question carries 5 marks
1. Write the structures of benzyloxy carbonyl, t-butyloxy carbonyl, fmoc and triphenyl methyl groups. 2. How carboxylic acid groups of peptides are protected and activated? 3. How alcohols are protected by ethers and silyl ethers. Explain with examples? 4. How alcohols are protected by TBDMS and THP. Explain with two examples? 5. How carbonyls are protected by acetal and ketal formation? Explain with examples? 6. Write a short notes on coupling with DCC 7. How the carboxylic acid groups are protected by ester formation? Explain with 2 applications 8. Explain briefly about acetal , ketal and carbonate formation for protection of 1,2 diols? 9. How the carboxylic acid group is protected by ortho-ester formation? 10. How amines are protected by fmoc and t-butoxy carbonyl compounds? 11. Discuss various methods for protection of amines? 12. How amines are protected by acetylation and benzoylation, 13. How amines are protected by benzyloxy carbonyl and triphenyl methyl groups? 14. Write about amino protecting groups in peptide synthesis? 15. Write about carboxylic acid protecting groups in peptide synthesis? 16. How the carboxylic acid groups are activated ? Explain with an example?
SECTION B
Each question carries 10 marks
1. a) Discuss briefly the stratergies involved in peptide synthesis b) How acetals and ketal formations are used in protection of carbonyls
2. a. Write a short note on the following protecting groups
i) fmoc ii) t-butyloxy carbonyl iii) benzyloxy carbonyl iv) benzoylation
3. a) How alcohols are protected by ethers and silyl ethers and esters. Explain
with examples?
b. How carbonyls are protected by acetal , ketal and thioacetal formation? Explain with examples?
4. a).Explain briefly the strategies involved in peptide synthesis?
b).How the carboxylic acid groups are protected by ester formation? Explain with 2 applications
5. a) Discuss the various methods of protectiong groups of amines
b) How alcohols are protected by ethers and silyl ethers and esters. Explain with examples?
6. a) How are 1,2 diols are protected by acetal, ketal and carbonate formation? b) How are carboxylic acids by ester formation and ortho ester formation?
7 a) How carbonyls are protected by acetal, ketal and thioacetal formation?
b) How alcohols are protected by TBDMS and THP?
8 a) Write a note on coupling with DCC and analogues? b) Explain briefly the stratergies involved in Protein synthesis
Organo Metallic Reagents & Organic Reactions of Synthetic Importance Section-A: Each question carries 5 marks.
1. What is Robinson annulation? Explain it with suitable examples. 2. Explain the mechanism involved in Peterson olefin synthesis & give two examples. 3. Explain reducing agent alkyl magnesium halide with mechanism. 4. Write a note on organo boranes in organic synthesis.give any two synthetic reactions. 5. Provide a method for the synthesis of Grignard reagent. 6. How olefins are obtained from Shapiro reaction. 7. How n-butyl lithium is prepared? Describe its use in alkylations of very weakly acidic organicsubstrates. 8. What is thexyl borane? Describe its selectivity in organo borane chemistry. 9. Give any two reactions choosing trimethyl silyl cyanide in organic synthesis. 10. What is Horner-Wittig reaction? Give its mechanism. 11. Write the mechanism & applications of Mannich reaction. 12. Illustrate the utility of trimethyl silyl halides in organic synthesis. o 13. i) R-OTs+ R2CuLi +ether +0 C ------ 1 ii) R-COOR + Me3SiI + THF ------ 14. Give any two synthetic reactions involving Grignard reagents to prepare
alcohols
15. Write the mechanism for following transformation with a suitable reagent.
16. Explain Stork Enamine reaction with suitable examples. 17.Explain applications of Organo phosphorous reagent in Wittig reaction.
18. What is meant by umpolung? Explain its significance.
19. Explain synthetic importance of Shapiro reaction.
20. Predict the products for following reactions.
Section-B: Each question carries 10 marks.
1.a. Explain the C-C bond formation in organoboranes. Give two examples.
b. Explain the mechanism involved in Shapiro reaction.
2.a. Describe the Synthetic importance involved in Wittig & Horner-Emmon’s
olefination.
b. Sketch the mechanism involved in organo lithium & organo copper reagents.
3. a. Write about Peterson olefination reaction.
b. Explain reducing agent alkyl lithium with mechanism.
4. a. Write about Organo silicon reagents.
b. Write about Tebbe reagent.
5. a. What are ylides? How are they prepared? Describe their use in condensations
with carbonyl compounds?
b. Give an account of Tebbe & Petasis reagent.
6. a. What are organo magnesium reagents? What is the role of solvent & initiator
in the preparation of these reagents? Write briefly on their applications in
synthesis.
b. Discuss the preparation & uses of trimethyl silyl chlorides & cyanides in
synthesis.
7. a. What is Peterson’s reaction? What type of stereo selective products are
Formed in this reaction.
b. What are organo copper reagents? Give their importance with four reactions.
8. a. Write a short note on Ti-carbene mediated olefination.
b. Write short note on organo lithium reagents. 9. a. Explain Reducing agent alkyl magnesium halides with mechanism.
b. What is Umpolung? Explain the use of dithioacetals.
10.a.Write a note on Organo boranes in organic synthesis.
b.Write about Petasis reagent.
11. a.Explain mechanism involved in Shapiro reaction.
b. Explain C-C bond formation in the organo boranes. Give two examples.
12. a. Describe the synthetic importance involved in Wittig- Horner Emmons
Olefination.
b.Sketch mechanism involved in alkyl lithium & alkyl copper reagents.
13. a. Write about Robinson annulations.
b. Write a note on Stork Enamine reactions.
14. a. Explain the synthetic applications of organo lithium compounds & organo
copper compounds.
b. Write the Structures of Products with mechanism of following reaction.
15. a. Using suitable Grignard reagent, formulate the synthesis of the compounds
A & B.
b. Explain the synthetic applications of organo silicon compounds.
16. Write short notes on following:
a) Mannich reaction b) Shapiro reaction.
17. a. What are Triflates? How are they Useful?
b. Which product is formed in the following reaction? How is it formed?
18. Illustrate the utility of following in the organic synthesis.
a. Organo lithium reagents
b. Organo boranes.
19. Illustrate the utility of following in the organic synthesis.
a. Organo silicon reagents
b. Organo copper reagents.
20. a.What are the synthetic applications of Lithium dialkyl cuprates? How is
Lithium dialkyl cuprate synthesised?
b. Write a brief account on Petersons stereoselective olefination reaction.
21. a. Give one method for preparation of Grignard reagent. b.C6H11MgBr + HC(OEt)3 ------? Predict the product & write the mechanism.
22. Explain the Use of following in organic synthesis.
a. Stork enamine reaction.
b. Trimethyl silyl halides.
23. Write short notes on the following:
a. Umpolung reaction b. Wittig-Horner-Emmons olefination.
24. a. What are the applications of PhLi, BuLi & LiR2Cu in the organic synthesis. b. Give examples of reactions involving β- carbocations & α- carbanions in
the organo silicon compounds.
25. a. Illustrate with examples the utility of 1,3-dithioacetals in the organic
Synthesis.
b. Discuss the mechanism & utility of Shapiro reaction.
26. a. Discuss the mechanism & stereochemistry of wittig reaction? Outline the
synthesis of Ar1-CH=CH-CH=CH-Ar2
b. Write a note on Tebbe reagent.
27. a. outline the synthetic applications of organo boranes in c-c bond formation.
b. Describe the applications of Grignard reagents in the synthesis of alcohols.
28. a. Outline the synthetic importance of petersons olefination.
b. Explain the synthesis of E & Z olefins using organo phosphorous reagents.
29. a. Explain the use of trimethyl silyl cyanide in the organic synthesis with two
examples.
b. Explain the synthetic importance of Robinson annulation reactions with examples.
30. a. Describe the carbonylation of organo boranes with suitable examples. b. Write briefly on the synthetic applications of the following reagents:
i) 9-BBN ii) Trimethyl silyl iodide
31. a. Write short notes on Aza-wittig reaction.
b. Write olefination by Nysted reagent.
32. a. Predict the products in the following reaction & write their structure.
b. Write the product & give mechanism of the following reaction.
New Synthetic Reactions
Section-A: Each Question carries 5 marks.
1. What is Suzuki coupling? Explain the mechanism involved in this by taking a suitable example.
2. Explain the role of reagents involved in Bayliss-Hillman Reaction.
3. Write about Sonogashira Reaction.
4. Explain Mc Murrey reaction.
5. State & explain Heck reaction.
6. What is Metathesis ? Discuss any two types of metathesis by giving examples.
7. Write about Mitsunobu reaction with mechanism by taking an example.
Identify the Y & Z in the above reaction.
9. Explain the stork enamine reaction with suitable mechanism.
10. What is stille coupling? Explain by giving an example.
11. Write about Buckwald Hartwig coupling reactions by giving an example.
12.Write the mechanism of Shapiro reaction with an example.
13.Explain Julia lythgoe olefination with mechanism by taking an example.
14. Explain Peterson olefination reaction..
15. what is UGI reaction. Explain mechanism with an example.
16. Explain Biginelli reaction with mechanism.
17. write about Mannich recation.
18. Write about Bergman cyclisation with example. 19. Write the mechanism of Nazerov cyclisation.
20. Write a note on click recation.
21. Write about sharpless azides cyclo addition.
22. Write about Eischenmoscher Tanabe Fragmentation.
23. Write the mechanism of aza wittig reaction.
24. Write about Michael Reaction with mechanism.
25. Complete the following reactions with mechanism.
26. Complete the following reactions with mechanism
27. Complete the following reactions with mechanism.
Section-B: Each question carries 10 Marks.
1. Give the mechanism of following synthetic reactions with suitable examples.
a. Mc Murrey reaction.
b. Shapiro reaction.
2. Give the mechanism of following synthetic reactions with suitable examples.
a. Mitsunobu reaction
b. Aza wittig reaction.
3. a. Write about Bayliss-hillmann reaction.
b. Write about Mc murrey reaction.
4. a. Write about Julia-Lythgoe reaction with mechanism.
b. Write about Michael recation with mechanism.
5. a. Explain the multi component UGI reaction.
b. Write about the stereoselectivity of Julia-Lythgoe reaction.
6. a. Write about Buckwald –Hartwig reaction.
b. write about RCM.
7. a. What is Suzuki Coupling reaction ? Discuss its use in synthesis giving
example.
b. What is Mannich reaction? Explain its use in the synthesis of Indole-3
acetic acid.
8. a. Discuss the importance of Stork enamine reaction in synthesis.
b. What are aza-cope & UGI reactions. Describe them giving their scope in
synthesis.
9. a. What is sonogashira Coupling? Give its mechanism with an example. b. Discuss Stille & Suzuki coupling reactions with examples.
10. a. Write a note on Heck reaction
b. Write about Shapiro reaction.
11. a. Identify X,Y & Z in the below reaction sequence.
b. Formulate Mukaiyama Aldol condensation, give examples.
12.a.
What is the product in the above reaction? Explain its formation.
b. What is Peterson Stereoselective reaction? Give two examples & formulate
sthe mechanism.
13.a. Explain the mechanism of Mc Murrey reaction.
b. write about Stereoselectivity of Julia-Lythgoe olefination.
14. a. Write the structures of Grubbs First & Second Generation catalysts.
b. Discuss the mechanism of Ruthenium catalysed olefin metathesis of 4-
methyl-1,7-octadiene.
15. a. Discuss RCM by taking an example of reaction. b. Write mechanism, discuss the coupling of organo tin compounds with Sp2
hybridized organic halides catalysed palladium.
16. a. Complete the following reactions with mechanism.
b. Write about Click reaction.
17.a. Write about Eischen moscher Tanabe fragmentation.
b. Write about Biginelli reaction.
18.a. Write the mechanism of the following reaction:
i. R-X + R1-Sn (R2)3 + L2Pd ------?
ii. R1-COOH + R-OH + DEAD/ PPh3 ------ ? b. Write about Bergman cyclization.
19.a. Write the mechanism of Nazerov Cyclization.
b. Write about Mannich reaction.
20. a. Write the mechanism of Micheal reaction.
b. Write the mechanism of sonagashira reaction.
21. a. Complete the following reactions with mechanism.
b. Complete the following reactions with mechanism.
22. a. Complete the following reactions with mechanism.
b. Write about Ring Closing metathesis. New techniques & Concepts in organic Synthesis