10. Addition Reactions

Predict the major products of the following reactions.

a. propene + BH₃⋅THF

b. the product from part (a) + H₂O₂/OH⁻

What is the major product obtained from hydroboration–oxidation of the following alkenes?

a. 2-methyl-2-butene

Identify A through O:

Predict the product of each of the following hydroboration–oxidation or oxymercuration–reduction reactions used in the modern synthetic organic chemistry literature (modified to use reagents we are used to seeing).

(b) A two-step hydroboration–oxidation was used to prepare a silanediol peptidomimetic as a serine protease inhibitor (Org. Lett. 2012, 14, 4422–4425).

Show how you would make the following compounds from a suitable cyclic alkene.

(e)

Suggest an alkene to undergo hydroboration–oxidation (1. BH₃ 2. NaOH, H₂O₂) to give exclusively the alcohols shown. Pay close attention to the relative (but not absolute) stereochemical outcome.

(d)

Predict the product(s) that would result when the alkenes shown here are allowed to react under the following conditions: (vi) 1. BH₃ 2. H₂O₂, NaOH

(k)

Show how you would synthesize each compound using methylenecyclohexane as your starting material.

(c)

Draw the organic products you would expect to isolate from the following reactions (after hydrolysis).

(m)

Show how you would accomplish the following transformations.

(c) 1-methylcycloheptanol → 2-methylcycloheptanol

Suggest a reagent to carry out each of the following conversions to an alcohol.

(d)

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

a. cyclohexene

b. 1-ethylcyclohexene

Show how you would accomplish the following synthetic conversions.

c. 2-bromo-2,4-dimethylpentane → 2,4-dimethylpentan-3-ol

At the beginning of Chapter 9, we stated that after finishing Chapters 8 and 9, we would have the ability to make a large variety of functional groups using related reactions. Show the reagent(s) necessary to convert 1-isobutylcyclohexene into the following molecules.

(g)

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