26. Amines

Show how you can synthesize the following tertiary amine three different ways, each using a different secondary amine and adding the final substituent by (b) acylation–reduction (3 ways).

The two most general amine syntheses are the reductive amination of carbonyl compounds and the reduction of amides. Show how these techniques can be used to accomplish the following syntheses.

(a) benzoic acid → benzylamine

Reduction of two different carboxylic acid derivatives with LiAlH₄ would give the amine shown. Identify these carboxylic acid derivatives.

Predict the product of the following reaction sequences.

(b)

Give the expected products of lithium aluminum hydride reduction of the following compounds (followed by hydrolysis).

(a) butyronitrile

(b) N-cyclohexylacetamide

(c) ε-caprolactam

Predict the products of the following reactions.

(e)

(f)

Show how each transformation may be accomplished by using a nitrile as an intermediate. You may use any necessary reagents.

(a) hexan-1-ol → heptan-1-amine

Show how to prepare the following aromatic amines by aromatic nitration, followed by reduction. You may use benzene and toluene as your aromatic starting materials.

(d) m-aminobenzoic acid

Show how you can synthesize the following compounds starting with benzene, toluene, and alcohols containing no more than four carbon atoms as your organic starting materials. Assume that para is the major product (and separable from ortho) in ortho, para mixtures.

(g) 4-isobutylaniline

Using any necessary reagents, show how you can accomplish the following multistep syntheses.

(b)

Show how you would accomplish the following synthetic conversions.

(a) benzyl bromide → benzylamine

Several additional amine syntheses are effectively limited to making primary amines. The reduction of azides and nitro compounds and the Gabriel synthesis leave the carbon chain unchanged. Formation and reduction of a nitrile adds one carbon atom. Show how these amine syntheses can be used for the following conversions.

(c) 1-bromo-3-phenylheptane → 3-phenylheptan-1-amine

Starting with cyclohexene, how can the following compounds be prepared?

b. cyclohexylmethylamine

How could you convert N-methylbenzamide to the following compounds?

a. N-methylbenzylamine

Predict the products of the following reactions:

(k)