LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – CHEMISTRY

LM 42

FOURTH SEMESTER – APRIL 2006

                                 CH 4954 – HETEROCYCLICS AND NATURAL PRODUCTS

(Also equivalent to CH 4951)

 

 

Date & Time : 25-04-2006/9.00-12.00         Dept. No.                                                       Max. : 100 Marks

 

 

Part- A

   Answer ALL questions.                    (10 ´ 2 = 20 marks)

1. How is isoquinoline synthesized?
2. Write the retrosynthesis of pyrimidine.
3. How is luciferin synthesized? What is its function?
4. How is the configuration of steroid nucleus defined? How does it affect the stability of nucleus?
5. During the synthesis of cholesterol, how is the B ring introduced?
6. What happens when quinoline is subjected to Hofmann’s exhaustive methylation method?
7. ‘Nametskin rearrangement plays a key role in the biological conversion of Terpenes”. Explain.
8. How would you convert acetophenone into tropic acid?
9. Convert: Carvone into Cadelene.
10. How are terpenes classified? Give an example for each.

Part – B

          Answer any EIGHT questions.             (8 ´ 5 = 40 marks)

11. How do pericyclic reactions help in the synthesis of heterocyclic compounds? Mention any two examples.
12. Predict the products in the following reactions.

 

 

13. Write a note on the electrophilic substitution reactions in thiazole with suitable example.
14. Explain Traube’s synthesis of uric acid.
15. How is oestriol synthesized from (±)-oestrone?
16. Describe any two ring closing reactions during synthesis of cholesterol.
17. Establish the structure of peepuloidin by synthesis.
18. How would you establish the structure of veratric acid?
19. Establish the structure of abietic acid by synthesis.
20. Give the structure of cocaine. How would you establish and confirm the structure of cocaine by synthesis?
21. How would you confirm the structure of papaverine by synthesis?
22. Establish the structure of camphoric acid.

 

Part-C

          Answer any FOUR questions.              (4 ´ 10 = 40 marks)

23     a) What happens when chromone is treated with hydrazine? Write the mechanism of the reaction.

1. b) Heterocyclic compounds are highly reactive than the corresponding homocyclic compounds. Give suitable explanation with examples.

24     a) Draw the resosnance structures of the following

1. i) isoquinoline              ii) pyridine                   iii) purine
2. b) How are the following heterocyclic compounds useful biologically
3. i) coumarin                  ii) flavone
4. c) What is Cornforth rearrangement?

25     a) How is the following conversion effected during the synthesis of cortisone?

 

1. b) What is the biological importance of steroids? Give any two examples.
2. a) Establish the structure of vitamin-A.
3. b) What are the functional groups present in heptaphylline? How would you confirm its structure?
4. a) Establish the structure of gibberelic acid.
5. b) How would you establish the structure of atropine by synthesis?
6. How would you convert the following:

• Tropine into 2-ethylpyridine
• 1,4-butanedial into ecgonine
• Camphoric acid into camphor
• 2,5-dimethoxytetrahydrofuran into tropinone.

 

 

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