10. Addition Reactions

Which of the following is the major organic product formed when 1-hexyne undergoes hydroboration–oxidation (using ${\mathrm{BH}}_3$ followed by $H{2}_O/\mathrm{OH}/H{2}_O{2}_{}$)?

Which of the following alcohols can be synthesized selectively by hydroboration-oxidation of an alkene?

Which of the following best describes the first step in the hydroboration mechanism when an alkene reacts with $B_{2}H6$ (diborane) in the presence of tetrahydrofuran (THF)?

Which of the following reagents can be used to convert $1-\mathrm{pentyne}$ into an $\mathrm{aldehyde}$ via hydroboration-oxidation?

Indentify the mechanism of reaction and predict the product.

Predict the product of the following reaction.

Draw the products, including their configurations, obtained from the reaction of 1-ethylcyclohexene with the following reagents:

c. R₂BH/THF, followed by HO^–, H₂O₂, H₂O

Show how each of the following compounds can be synthesized from an alkene:

c.

Draw the product or products that will be obtained from the reaction of cis-2-butene and trans-2-butene with each of the following reagents. If a product can exist as stereoisomers, show which stereoisomers are formed.

2. BH₃/THF, followed by HO^-, H₂O₂, H₂O

What stereoisomers are obtained from hydroboration–oxidation of the following compounds? Assign an R or S configuration to each asymmetric center.

d. (Z)-3,4-dimethyl-3-hexene

What stereoisomers are obtained from hydroboration–oxidation of the following compounds? Assign an R or S configuration to each asymmetric center.

c. cis-2-butene

Which is more highly regioselective: reaction of an alkene with BH₃ or with 9-BBN?

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

(c)

When (E)-3-methylhex-3-ene undergoes hydroboration–oxidation, two isomeric products are formed. Give their structures, and label each asymmetric carbon atom as (R) or (S). What is the relationship between these isomers? What is the relationship between the products formed from (Z)-3-methylhex-3-ene and those formed from (E)-3-methylhex-3-ene?

Predict the major products of the following reactions. Include stereochemistry where applicable.

(c)