10. Addition Reactions

What alkene gives the product shown after reaction first with ozone and then with dimethyl sulfide?

c.

The following products were obtained from the oxidative cleavage of a diene. What is the structure of the diene?

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

c.

d.

The following product was obtained from the ozonolysis of an alkene followed by treatment with dimethyl sulfide. What is the structure of the alkene?

a.

The following product was obtained from the ozonolysis of an alkene followed by treatment with dimethyl sulfide. What is the structure of the alkene?

b.

One of the constituents of turpentine is α-pinene, formula C₁₀H₆. The following scheme (called a “road map”) gives some reactions of α-pinene. Determine the structure of α-pinene and of the reaction products of A through E.

Problem 8-54 describes a new method to perform ozonolysis reactions that used pyridine (py) to generate the final aldehydes and ketones in a non-aqueous reaction medium. In a subsequent publication (J. Org. Chem., 2013, 78, 42), Professor Dussault (U. of Nebraska at Lincoln) described a “tandem” process in which two reactions are performed sequentially without having to isolate the intermediate aldehyde or ketone. Show the final product from each sequence. (Hint: The isolated products were from the larger part of the structure. Ignore stereochemistry.)

(a)

(b)

Problem 8-54 describes a new method to perform ozonolysis reactions that used pyridine (py) to generate the final aldehydes and ketones in a non-aqueous reaction medium. In a subsequent publication (J. Org. Chem., 2013, 78, 42), Professor Dussault (U. of Nebraska at Lincoln) described a “tandem” process in which two reactions are performed sequentially without having to isolate the intermediate aldehyde or ketone. Show the final product from each sequence. (Hint: The isolated products were from the larger part of the structure. Ignore stereochemistry.)

(c)

(d)

Deduce the structure of each compound from the information given. All unknowns in this problem have molecular formula C₈H₁₂.

(c) Upon catalytic hydrogenation, unknown Y gives cyclooctane. Ozonolysis of Y, followed by reduction with dimethyl sulfide, gives a three-carbon dialdehyde and a five-carbon dialdehyde. Draw the structure of Y.

(d) Upon catalytic hydrogenation, unknown Z gives cis-bicyclo[4.2.0]octane. Ozonolysis of Z, followed by reduction with dimethyl sulfide, gives a cyclobutane with a three-carbon aldehyde (–CH₂–CH₂–CHO) group on C1 and a one-carbon aldehyde (–CHO) group on C2. Draw the structure of Z.

Predict the major products of the following reactions, and give the structures of any intermediates. Include stereochemistry where appropriate.

(d)

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.

(a)

(b)

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.