10. Addition Reactions

For each of the following alkynes, draw the products obtained from (1) the acid-catalyzed addition of water (mercuric ion is added for part a) and from (2) hydroboration–oxidation:

a. 1-butyne 

The hydroboration–oxidation of internal alkynes produces ketones.

b. When hydroboration–oxidation is applied to pent-2-yne, two products are obtained. Show why a mixture of products should be expected with any unsymmetrical ­internal alkyne.

What are products of the following reactions?

e.

Show how you would accomplish the following synthetic transformations. Show all intermediates.

j. trans-hex-2-ene → cis-hex-2-ene

Predict the product of the following aldehyde/ketone syntheses.

(c)

How can the following compounds be prepared using ethyne as the starting material?

a.

For each compound, give the product(s) expected from (1) HgSO₄/H₂SO₄ - catalyzed hydration and (2) hydroboration–oxidation.

d. cyclodecyne

a. Explain why a single pure product is obtained from hydroboration–oxidation of 2-butyne, whereas two products are obtained from ­hydroboration–oxidation of 2-pentyne.

b. Name two other internal alkynes that yield only one product upon hydroboration–oxidation.

Predict the major products of the following reactions.

d. trans-cyclodecene + peroxyacetic acid in acidic water

e. cis-cyclodecene + mCPBA in CH₂Cl₂, then dilute aqueous acid

For the alkynes shows here, show the product(s) expected to form when treated under the following conditions: (vii) 1. BH₃ 2. H₂O₂, NaOH. If you expect two products, show both.

(c)

What is the major product of the reaction of 1 mol of propyne with each of the following reagents?

e. aqueous H₂SO₄, HgSO₄

f. R₂BH in THF followed by H₂O₂/HO⁻ /H₂O

For each compound, give the product(s) expected from (1) HgSO₄/H₂SO₄ - catalyzed hydration and (2) hydroboration–oxidation.

c. hex-3-yne

The hydroboration–oxidation of internal alkynes produces ketones.

a. When hydroboration–oxidation is applied to but-2-yne, a single pure product is obtained. Determine the structure of this product, and show the intermediates in its ­formation.

For each compound, give the product(s) expected from (1) HgSO₄/H₂SO₄ - catalyzed hydration and (2) hydroboration–oxidation.

b. hex-2-yne