SIKKIM UNIVERSITY Department of Chemical Sciences CHE-PG-0202: Organic Chemistry IIEnd semester: Spring, 2015Dr. Biswajit G. Roy

Total Marks: 50 Time: 2 hSection AAnswer any Five questions (5 x 10 = 50)

1. Give mechanism for each of the following photo chemical reaction.5 x 2 = 10

2. Write product(s) of following reactions with proper mechanism.5 x 2 = 10

3. Predict the products of following photochemical reaction? Give mechanism in each case. 5 x 2 = 10

4. a) How will you carry out following transformations? Give mechanism and reason behind selecting that particular reagent.4 x 2 = 8

b) Write protection and deprotection steps amine group using 9-Fluorenylmethyl Carbamate (Fmoc). give mechanism for the steps.2

5. a) Write reagents or major products of following reactions. Give proper mechanism for each reaction. 6

i)ii)

iii) iv) b) Write short notes on i) Mitsoonobu Reaction and ii) Swern Oxidation mentioning purpose, reagents, conditions, mechanism, and product generates in the reactGive reagents for following transformations. 46. a) Write suitable reagents only for following multi step transformations.10

b)

7. a) Why compound A is used as a photosenstizer and compound B used as a photostabilizer?2.5

b) Following hetero bicyclic compounds show strikingly different reactivity towards electrophiles and nucleophiles. Explain their reactivities with proper reasoning and examples. 2.5

c) AAC2 mechanism of ester hydrolysis is feasible for compound but not for compound B. Give reason for their difference in behavior towards ester hydrolysis. What reagent will you use for hydrolysis of compound B and why?2.5

d) In Diels-Alder reaction of cyclopentadiene and maleic anhydride following products A and B is generated. At 0 oC compound A is predominant but at refluxing condition in THF, B is the predominant product. Explain why?2.5

Thank You