10. Addition Reactions

Propose mechanisms for the epoxidation and ring-opening steps of the epoxidation and hydrolysis of trans-but-2-ene shown above. Predict the product of the same reaction with cis-but-2-ene.

Draw all possible resonance contributors for the two carbocations in the preceding reaction. Use the resonance contributors to explain why 1-naphthol is the major product of the reaction.

Three arene oxides can be obtained from phenanthrene.

a. Draw the structures of the three phenanthrene oxides.

Propose mechanisms consistent with the following reactions.

(f)

b. A small amount of a product containing a six-membered ring is also formed. Draw the structure of that product.

c. Why is so little six-membered ring product formed?

Show an arrow-pushing mechanism for reactions 1–4 in Figure 9.37.

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When 1,2-epoxycyclohexane (cyclohexene oxide) is treated with anhydrous HCl in methanol, the principal product is trans-2-methoxycyclohexanol. Propose a mechanism to account for the formation of this product.

Predict the product(s) that would result when the alkenes are allowed to react under the following conditions: (vii) 1. mCPBA 2. H₂SO₄, H₂O

(k)

Suggest mechanisms for the following reactions, which are similar to the mechanism we saw for lanosterol biosynthesis at the end of Chapter 8.

(a)

Working backward, design a synthesis of the following alcohol using two different epoxide/Grignard reagent combinations.

Show how you would accomplish the following conversions.

b. cis-hex-3-ene to (d,l)-hexane-3,4-diol

Predict the product of the following epoxide addition reactions.

(b)

Predict the product(s) that would result when the alkenes are allowed to react under the following conditions: (vii) 1. mCPBA 2. H₂SO₄, H₂O

(d)

Predict the major products of the following reactions.

b. trans-hex-3-ene + peroxyacetic acid (CH₃CO₃H) in water

c. 1-methylcyclohexene + MMPP in ethanol