Chem 227 - Harding

Exam 2 - Spring 1998

1. (4 pts) Draw structures corresponding to each of the names below.

a) 1,2-diethylcylopentene b) (Z)-1-Bromo-3,4-dimethyl-3-hexene




2. (3 pts) Provide the product of the following reaction used in the synthesis of Kampane diterpenes (J. Amer. Chem. Soc. 1997, 119, 9584)



3. (6 pts)

a) Provide the structure of a (Z)-alkene that could produce 3-pentanol upon hydroboration-oxidation:



b) Hydroboration-oxidation of the alkene you drew could have formed another regioisomeric product. What is its structure?



c) Which of these two products (if either) is expected to be the major product? Explain.





4. (4 pts) Rank the substituents below using Cahn-Ingold-Prelog sequence rules by numbering the highest priority substitutent as 1 and the lowest priority group as 4.

5. (9 pts) 1-Methylcyclohexene reacts with hydrazoic acid by an electrophilic addition reaction.

a) Write the structure of the expected major product for this reaction in the box labeled Z.

b) Using the curved-arrow notation, provide a complete step-wise mechanism for this reaction showing all intermediates (6 pts).


6. (10 pts) Consider the reaction below to answer the following questions.


a) Draw the appropriate structures for the boxes.

b) The hydroboration step is an example of: (Circle your answer)

I. syn addition I
I. anti addition
III. radical chain reaction I
V. oxidation

c) The overall reaction is an example of: (Circle your answer)

I. Markovnikov addition
II. oxidation reaction
III. non-Markovnkov addition
IV. reduction reaction

7. (18 pts) Predict the major organic products in each reaction below. Be sure to indicate stereochemistry when appropriate.

a)



b)


c)



d)


e)



f)



8. (15 pts) Provide the necessary starting materials or reagents to complete the following conversions.

a) The following reaction is effected by a single reagent in one step. What must it be? (Hint: You will not find this reaction on your reminder sheet.)


b)


c)



d)

e)

9. (4 pts) Trichlorosalicylanilide is an antiseptic agent with formula C13H8NO2Cl3. Calculate the number of rings plus double bonds (degreees of unsaturation) for trichlorosalicylanilide Show your calculations.





10. (6 pts) The ether C is a compound that can be substitued for tetraethyllead to improve the octane rating of gasoline. This ether is synthesized by reaction of 2-methylpropene (A) with methanol (B) using a small amount of a strong acid such as sulfuring acid as a catalyst. The reaction occurs with very high regioselectivity forming only compound C and none of compound D.


a) (2 pts) This overall reaction (A + B -----> C) would be classified as what kind of reaction?

b) (4 pts) Explain why compound C is formed instead of compound A (Be brief).




11. (6 pts) Substance Q can produce substance W or substance Y as shown by the energy diagram shown below. Use this diagram to answer the following questions.

a) How many intermediates are involved in these reactions?
b) The Dgo for the formation of the more stable product occurs between which points?
c) The activation energy for product that will be formed faster occurs between which points?

12. (4 pts) Complete the following reaction by giving reagent and product.

13. (9 pts) Draw structures for the reactive intermediates expected to be formed in the first step of each of the following reactions:

a)





b)



c)



14. (2 pts) Give an example of a termination reaction for free radical chlorination of methane.