10. Addition Reactions

Predict the products you would get when the following alkenes undergo (ii) oxymercuration–reduction [1. Hg(OAc)₂ , H₂O 2. NaBH₄ ].

(b)

a. Show the reagents required to form the primary alcohol in each of the following reactions.

What reagents are needed to synthesize the following alcohols?

The bulky borane 9-BBN was developed to enhance the selectivity of hydroboration. In this example, 9-BBN adds to the less hindered carbon with 99.3% regioselectivity, compared with only 57% for diborane.

b. 9-BBN is synthesized by adding BH₃ across a symmetric, cyclic diene. What is the structure of the diene?

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

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

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

What reagents are needed to carry out the following syntheses?

Suggest a reagent and a reactant that could be combined to make each of the following alcohols.

(a)

Devise a synthesis for each compound, starting with methylenecyclohexane and any other reagents you need.

d. trans-2-methylcyclohexanol

Hydroboration, an electrophilic addition reaction like those studied in Section 21.4, only gives 1,2-addition to buta-1,3-diene, regardless of temperature. Why?