Question

Show how you would accomplish the following synthetic conversions.

(a) benzyl bromide to benzylamine

(b) 1-bromo-2-phenylethane to 3-phenylpropan-1-amine

(c) pentanoic acid to pentan-1-amine

(d) pentanoic acid to hexan-1-amine

(e) (R)-2-bromobutane to (S)-butan-2-amine

(f) (R)-2-bromobutane to (S)-2-methylbutan-1-amine

(g) hexan-2-one to 1-amino-2-methylhexan-2-ol

Short answer

The synthetic conversions are accomplished as below.

(a)

(b)

(c)

(d)

(e)

(f)

(g)

Step-by-step solution

SN2 path

The conversion is based on the nucleophillic substitution. And this is ${\text{S}}_{\text{N}}\text{2}$. Bromine is the leaving group and the ammonia is the nucleophile.

The conversion is based on the nucleophillic substitution. And this is ${\text{S}}_{\text{N}}\text{2}$. Bromine is the leaving group and the ammonia is the nucleophile.

(b)

Reduction using LiAlH4

The carboxylic acid group is converted to carboxyl amine group by the addition of ammonia. It is then converted to amine by the reduction of LiAlH4.

(c)

Reducton then TsCl and then KCN and then again reduction

Pentanoic acid is reduced by lithium aluminum hydride then the OH group is converted to OTs by the addiotion of TsCl. It is then treated with KCN and reducing agent to get the product.

SN2 path

The conversion is based on the nucleophillic substitution. And this is ${\text{S}}_{\text{N}}\text{2}$. Bromine is the leaving group and the ammonia is the nucleophile.

NaOH addition then TsCl and then KCN and then again reduction

Using ${\text{S}}_{\text{N}}\text{2}$path the Bromine group is left and then OH group is added and the streochemisty is changed. The tosyl chloride is added and then KCN is added and lastly a good reducing agent convert it to the product.

Grignard reagent

Using Grignard reagents we can convert to the following product. And the addition of water can convert the keto group to alcohol.

(g)