CLASS: M.SC. CHEMISTRY
J697A7
ST. JOSEPH’S COLLEGE (AUTONOMOUS), TIRUCHIRAPPALLI - 620 002
SEMESTER EXAMINATIONS – APRIL 2007
TIME: 3 Hrs.
MAX. MARKS: 100
SEM
SET
PAPER CODE
SUBJECT
IV
2005
04PCH436
SYNTHETIC METHODOLOGY
SECTION – A
Answer all the questions:
10 x 3 = 30
1. Prove that the given reaction is an umpolung reaction
HCHO + HS(CH2)3SH
i) BuLi
ii) RX
iii) H 2O
HS(CH2)3SH + R - CHO
2. Write down the synthetic equivalents for the following synthons:
a)
3.
O


R CO
b)
R C  C
c)
Predict the products:
a) PhCHCl2
Me2CuLi
?
CH3
b) Ph
C
O
C
C
CH3 O
Ph
TiCl4
LiAlH 4
?
R - C - CH2
4. Indicate the involvement of ene reaction and sigmatropic rearrangement respectively in the
following reaction
R
H
C
H
SeO2
C
RCH
CH
CHO
CH3
5. Expand the following abbreviations. Draw their structures:
a) LDA
b) DCC
c) NBS
6. Write the difference between functionalization and functional group interconversion. Give
an example for each.
7. Write down the classification of alkaloids.
8. Define – Over voltage.
9. What are nucleosides and nucleotides? Give an example for each.
10.Differentiate conjugated proteins and simple proteins.
SECTION – B
Answer all the questions:
11. a.
5 x 14 = 70
Propose the most suitable synthons and synthetic equivalents of
p - bromoacetanilide. Write the retrosynthetic path from
bromoacetanilide to benzene.
b. Discuss on donor synthons and acceptor synthons.
O
(5)
(5)
O

c.
p -
+
Is it a good disconnection? Rationalise your answer.
(4)
(OR)
d. Write the name of any two reactions involving ring closure and suggest the
retrosynthesis of
(5)
O
O
OMe
e. How would you prepare
(5)
O
CO2H
by retrosynethic method.
f. What are stereoselective reactions? Explain.
12. a.
i)
(4)
Write the mechanism for the following conversions.
O
CO2C2H5
H3C
H3C
CH2Br
(4)
O
Bu3SnH
AlBN
CH3
CH3 - C - CH2 - CH - CO2C2H5
DDQ
ii)
b. Discuss Woodward and prevost hydroxylation with mechanism.
(6)
c. Explain the use of Trimethylsilyliodide.
(4)
(OR)
d. Predict the products and name the reactions.
(6)
O
i)
i) Pyrrolidine
ii) CH 2 = CHCH2Br
iii) H 2O
?
O
ii)
+ C6H5CH = PPh3
?
Li
iii) Me3SiCHCN +C6H5CH = CHCHO
?
e. Write short notes on Merifield resin.
(4)
f. Discuss on phase transfer catalyst.
(4)
13. a. Assign the reagents for the following conversions:
(3)
O
R - C - O - R'
O
R - C - R'
RCH2R'
OH
R - C - R'
R"
b. Suggest the mechanism for Michael reaction.
(5)
c. Predict the products with appropriate stereochemistry.
(6)
O
R
i)
Baker yeast
?
O
H
H
OsO4
ii)
R
iii)
?
R
H
CH3(CH2)2
CH2OH
H
(+) diethyl tartrate
Ti (o - iPr)4, t - BuOOH
(OR)
?
d. Write a note on Wilkinson’s catalyst.
(5)
e. With two examples, explain the reagents assigning as chemoselective for organic
reactions.
(5)
f. Using norbornene, obtain the following product by hydroboration method.
(4)
OH
14. a. Elucidate the structure of papaverin.
b. What is meant by biosynthesis.
terpenoids.
(8)
Explain the steps involved in biosynthesis of
(6)
(OR)
c. Elucidate the structure of zingiberene.
(7)
d. Discuss the electrolytic reduction of nitrogroup in nitrobenzene.
(4)
e. Write the classification of terpenoids.
(3)
15. a. Discuss clearly the primary, secondary, tertiary and quarternary
structure of protein.
b. Describe any six differences between DNA and RNA.
(8)
(6)
(OR)
c. Discuss Watson – Crick model of DNA molecule.
(6)
d. What are harmones? Give the broad classification of harmones.
(3)
e. Write a note on Vitamins.
(5)
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