10. Addition Reactions

Predict the product(s) that would result when the alkenes are allowed to react under the following conditions: (vi) 1. OsO₄ 2. NaHSO₃

(h)

The two butenedioic acids are called fumaric acid (trans) and maleic acid (cis). 2,3-Dihydroxybutanedioic acid is called tartaric acid.

Show how you would convert

a. fumaric acid to (±)-tartaric acid.

b. fumaric acid to meso-tartaric acid.

What stereoisomers are obtained from the reaction of each of the following alkenes with OsO₄ followed by aqueous H₂O₂?

a. trans-2-butene

b. cis-2-butene

Predict the product(s) of each of the following reactions, making sure to indicate the relative stereochemical outcome. Indicate any racemic mixtures by drawing both enantiomers.

(b)

Predict the major products of the following reactions, including stereochemistry.

c. cis-pent-2-ene + OsO₄/H₂O₂

d. cis-pent-2-ene + peroxyacetic acid in water

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

(i)

Predict the major products of the following reactions.

f. 1-ethylcycloheptene + cold, dilute KMnO₄

Retrosynthetic analysis is the process of working backward to develop the synthesis of a new compound. In Chapter 10, we begin developing multistep syntheses in this manner. For now, try to work backward a single step by suggesting an alkene and a reagent that would give products (a)–(i). [Your answers should not include alkenes that undergo rearrangement to give the desired products.]

(a)

How might you make the catalytic cycle in Figure 9.31 more sustainable while still using NMO as the co-oxidant?

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Predict the major products of the following reactions, including stereochemistry where appropriate.

(k) cyclopentanol + H₂SO₄/heat

(l) product from (k) + OsO₄/H₂O₂, then HIO₄

(m) sodium ethoxide + 1-bromobutane

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

c. 1-(hydroxymethyl)cyclohexanol

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

(h)

The concertedness of the OsO₄ reaction results in both oxygens being added to the same face of the molecule (i.e., syn addition). How might these conditions be modified in order to prepare a trans-diol?