10. Addition Reactions

Give structures of the alkenes that would give the following products upon ozonolysis–reduction.

(c)

Using 1,2-dimethylcyclohexene as your starting material, show how you would synthesize the following compounds. (Once you have shown how to synthesize a compound, you may use it as the starting material in any later parts of this problem.) If a chiral product is shown, assume that it is part of a racemic mixture.

(i)

Show how you would synthesize each compound using methylenecyclohexane as your starting material.

(d)

Ozonolysis can be applied selectively to different types of carbon–carbon double bonds. The compound shown below contains two vinyl ether double bonds, which are electron-rich because of the electron-donating alkoxy groups. Ozone reacts more quickly with electron-rich double bonds and more slowly with hindered double bonds. At −78 °C, this compound quickly adds two equivalents of ozone. Immediate reduction of the ozonide gives a good yield of a single product. Show the expected ozonolyis product, and label the functional groups produced, some of which are not typical from ozonolysis of simple alkenes.

Professor Patrick Dussault (University of Nebraska at Lincoln) has developed an alternative to the standard two-step ozonolysis procedure requiring reduction of the ozonide in a second step. He uses 2 to 3 equivalents of pyridine, a mildly basic organic solvent, in a one-step process (Organic Letters, 2012, 14, 2242). Show the products you expect from the following examples.

(c)

(d)

Predict the major products of the following reactions.

(c)

(d) 1-ethylcycloheptene + ozone, then (CH₃)₂S

What products are formed when the following compounds react with ozone and then with dimethyl sulfide?

e.

f.

Ozonolysis of an alkene, followed by treatment with dimethyl sulfide, forms the following product(s). Identify the alkene in each case.

a.

What is the major product of the reaction of 2-methyl-2-butene with each of the following reagents?

d. O₃, −78 °C, followed by (CH₃)₂S

What aspect of the structure of the alkene does ozonolysis not tell you?

What reagents are needed to carry out the following syntheses?

In contact with a platinum catalyst, an unknown alkene reacts with three equivalents of hydrogen gas to give 1-isopropyl-4-methylcyclohexane. When the unknown alkene is ozonized and reduced, the products are the following:

Deduce the structure of the unknown alkene.