Question 1

Devise a synthetic route for this conversion. Deuterium can be introduced by replacing the hydrogen in common reagents with its deuterium analog.

Accepted Answer

This transformation is simply a hydroboration-oxidation reaction where the source of deuterium is BD₃ (replacing BH₃). The deuterium adds to the more substituted alkene carbon while the hydroxy group will end up on the less substituted alkene carbon.

This transformation is simply a hydroboration-oxidation reaction where the source of deuterium is BD<sub>3</sub> (replacing BH<sub>3</sub>). The deuterium adds to the more substituted alkene carbon while the hydroxy group will end up on the less substituted alkene carbon.

Question 2

Compare the results of hydroboration-oxidation and Hg2+-catalyzed hydration for 2-butyne versus 1-butyne. For which is the result of the two reactions the same and which results are different?

Accepted Answer

2-Butyne is a symmetrical alkyne and both reactions will give the same ketone product.

1-Butyne is a terminal alkyne and will give an aldehyde using hydroboration-oxidation and a ketone using Hg²⁺-catalyzed hydration.

Question 3

Draw the structures of three enols that would be spontaneously converted into the following ketone. (Don't forget stereoisomers.)

Accepted Answer

The enols are formed by removing an alpha proton from each side of the ketone and forming a pi bond. The three enols are

Question 4

A student allowed an alcohol, 4-penten-1-ol, to react with Br2, expecting to observe a simple addition of Br2 to the double bond. Instead, she isolated a compound X that proved to have the formula C5H9OBr. The reaction mixture from which X was isolated was very acidic.
   Using mechanistic reasoning, including the curved-arrow notation, propose a structure for compound X. Show your logic at every step of the way! Your answer should explain why the reaction mixture became acidic.

Accepted Answer

When alkenes react with bromine, typical

Question 5

Complete the reaction by providing the structure of the missing product.

Accepted Answer

The answer of Complete the reaction by providing the structure...

Question 6

Give the structure of the enol intermediate in the hydration of 1-pentyne.

Accepted Answer

The answer of Give the structure of the enol intermediate...

Question 7

Consider the reaction, in which X is a stable, mercury-containing compound (not a reactive intermediate). Compound Y does not react with either Br2, H2/catalyst, or ozone.
   a. What do you deduce about the structure of Y solely from its formula and the reactivity (or "unreactivity") data give? Explain briefly.
b. Use mechanistic reasoning to deduce the structure of X. Use the curved-arrow notation; show all relevant unshared pairs and charges. Then, using what you know about step (2)-no mechanisms!-deduce the structure of the product Y.

Accepted Answer

a. The reactivity data shows that the me

Question 8

Devise a synthetic route for this conversion.

Accepted Answer

The number of carbons remains the same i

Question 9

Identify the reagents needed to transform isopentene to the product shown.

Accepted Answer

The answer of Identify the reagents needed to transform isopentene...

Question 10

Complete the reaction by providing the structure of the missing starting material.

Accepted Answer

The answer of Complete the reaction by providing the structure...

Question 11

Complete the reaction by providing the structure of the missing product. (Ignore byproducts.)

Accepted Answer

The answer of Complete the reaction by providing the structure...

Question 12

Complete the reaction by providing the missing starting material.

Accepted Answer

The answer of Complete the reaction by providing the missing...

Question 13

Complete the reactions by giving the missing starting material, which is the same for both reactions.

Accepted Answer

The answer of Complete the reactions by giving the missing...

Question 14

Devise a synthetic route for this conversion.

Accepted Answer

The overall number of carbons remains th

Question 15

Consider the scheme.
   a. Draw the structure of intermediate X, which has the formula shown under in the box provided.
b. What special kind of functional group is present in intermediate X?
c. What special kind of functional group is present in the product?