Download Advanced Chemistry

1
1. a)Write down the sequence of steps (names only) involved in the solid phase
synthesis of deoxy oligonucleotides by phosphoramidite method.
b)Show hydrogen bonds between A & T and C & G by drawing the appropriate
structures.
3+2=5
2. (a) Adenine comprised 36% of the nitrogenous bases in the double stranded DNA
of cells from a bacterial clone. What was the percentage of guanine in this DNA?
What will be percentage of thymine in the single-stranded DNA?
(b) A, B, C are three different amino acids. How many dipeptides are possible
to be synthesized from these amino acids?
(c) A, B, C and D are four nucleosides. How many triplet codons are possible to
be formed?
2+1+1=4
3. (a) Which of the following is involved in the inter-chain linkage between
complementary strands of DNA?
2+2+2=6
(i). Covalent bonding between the sugar and nitrogenous bases
(ii). Covalent bonding between the sugar and the phosphate groups
(iii). Covalent bonding between adjacent sugar groups
(iv). Hydrogen bonding between the nitrogenous bases
(v). Hydrogen bonding between adjacent sugar groups
(b) The mRNA codons of amino acids in a sequence of part of a polypeptide
chain are shown below.
UGU-GAU-CAC-UAG-GAU-AAG-CAC.
Which DNA base sequence could provide the code for this section of
polypeptide?
(i). ACA-CTA-GTG-ATC-CTA-TTC-GTG
(ii). ACA-CTA-GTG-ATG-CTA-AAC-GTG
(iii). ACA-CTT-GTG-ATG-CTA-TTC-GTG
(iv). ACA-CUA-GUG-AUG-CUA-UUC-GUG
(v). CAC-ATC-UTU-CTU-ATC-TTA-UTU
(c) Which statement correctly describes the transcription of DNA?
(i). It produces amino acids.
(ii). It produces messenger RNA.
(iii). It results in increased DNA synthesis.
(iv). It is a semi-conservative process.
(v). It occurs at the surface of the ribosome.
2
4.
3x2=6
A drug discovery program resulted in the three classes of compounds (Step 1) -- A, B and
C. R1, R2 and R3 represent different sites for anchoring substituents. The class B was
found to be active after screening. After routine manipulations utilizing the sites R1, R2
and R3, the compound C was established to be the most active and is eventually approved
by the authority to be marketed as a drug. The problem is, the method shown in the
scheme below is not cost effective.
Please, indicate—
(i)
(ii)
(iii)
Which of the steps will involve combinatorial chemistry?
Which is the complexity-generating and, hence, diversity-oriented synthetic
step?
From the informations given in the above statement, do you expect any role of
target-oriented synthesis in this drug discovery program?
R2
R1
A
Starting
materials
Step 1
Single
reaction
R1
R1
R3
Step 2
B
Screening
R2
R3
R3
R1
R2
C
R2
B
Active group
R3
Step 3
Me
Ph
Bn
C
Most active drug
Approved by authority
Method not cost effective
3
5. a) What is the natural source of taxol?
b) What were the initial problems for taxol research? How the problems
have been solved?
c) What are structural elements present in taxol?
d) Enumerate the synthesis of taxol side chain using β-lactam approach
1+2+1+3+3=10
6. a) Draw the structure of sucrose indicating the linkage type.
b) What is the structural difference between Starch and Cellulose ?
c). (i) What will be the mirror image of methyl α-D-mannopyranoside
(ii) Which sugar is 4 -epimer of D-glucose.
d) What is mutarotation? Explain with suitable example.
e) Give the reaction product(structure) of Glucose witha) Andydrous methanolic HCl
b) Sodium Borohydride followed by mixture of acetic anhydride and pyridine.
1+1+2+2+2+2=10
2.Cyclization of 6-heptenyl bromide in presence of Bu3SnH/AIBN ( cat amount)
/benzene at refluxing temperature furnished selectively one major product. Why
one product is predominant? Justify your answer giving structures and
conformational aspect of the products. What is the structure of minor product?
1+1+1=3
B. Write down the structure of the products
A, B and C (any three)
3x4 = 12
4
PhMe, 80

C
A
(a)
MeS
N
N
N
COCF3
MeS
Ph
Cl
Ru
Cl
1 mol %
(b)
I
CH 3
Bu3SnH-AIBN
B
BENZENE
Ref lux
H
H
O
(c)
SmI2(2.2 eq) /HMPA(8 eq)
BuOH
C
Ph
-25 oC
8. a) Define DEPT 135 in terms of ethylacetoacetate?.
THF
2+2+1+2=7
b) Give the possible 1H-13C HSQC spectra of indole?.
c) HMBC experiment allows you to correlate carbons (or other X nuclei) and
protons linked through:
a. one bond
b. more than one
c. more than two
5
e) What should be the 1H-1H COSY spectra of toluene?
9)
1+1=2
Tick the right answer
i) In drug metabolic process, Cytochrome P450 enzyme mainly acts as
a) Esterase b) Oxidase
c) Dehydrogenase d) Reductase
ii) Iridoids basically belongs to the class of
a) Monoterpene b) Diterpene c) Sesquiterpene d)Triterpene