Question

Devise a synthesis of each compound from the given starting materials. You may also use organic alcohols having four or fewer carbons, and any organic or inorganic reagents

a)

b)

c)

Short answer

a)

Step 1

Step 2

Step 3

Step 4

Step 5

b)

Step 1

Step 2

c)

Step 1

Step 2

Step-by-step solution

Etard reagent

Chromyl chloride (CrO₂Cl₂) is known as Etard reagent.

Methyl group on benzene is oxidized by Etard reagent to a chromium complex. On hydrolysis, it finally produces the corresponding aldehyde.

Synthesis of the compound from given starting material

(a)

• Phenol reacts with methyl chloride in presence of Lewis acid to give 4-methyl phenol.

4-methyl phenol reacts with NaH in presence of methyl bromide to give 4-methyl-anisole

Step 1

• 4-methyl anisole reacts with NBS (N-Bromosuccinimide) in the presence of carbon tetrachloride to give 1-(bromomethyl)-4-methoxybenzene 1-(bromomethyl)-4-methoxybenzene reacts with triphenylphosphine in the presence of NaH to give a Wittig reagent

Step 2

• Benzene reacts with 2-chloro-2-methylpropane in the presence of Lewis acid to give tert-butyl benzene.

Tert-butyl benzene reacts with methyl chloride in the presence of Lewis acid to give 1-(tert- butyl)-4-methylbenzene

Step 3

• 1-(tert-butyl)-4-methylbenzene reacts with Etard reagent to give 4-(tert-butyl) benzaldehyde.

Step 4

• The Wittig reaction between 4-(tert-butyl) benzaldehyde and a Wittig reagent (form step 2) give both cis and trans isomers of compound (a)

Step 5

(b)

• The carbonyl group of the ketone is protected using 1,2-ethanediol in the presence of acid.

Alcohol reacts with PBr₃ to give alkyl bromide

Step 1

• Alkyl bromides react with Mg in presence of dry ether to give Grignard reagent.

2-propanol undergoes oxidation with PCC to give 2-propanone Grignard reagents react with 2-propanone in presence of water to give a tertiary alcohol.

Step 2

c)

• Benzene reacts with isobutyryl chloride in the presence of lewis acid to give 2-methyl-1-phenylpropan-1-one.

Step 1

• 2-methyl-1-phenylpropan-1-one reacts with diethyl amine to give desired compound N, N-diethyl-2-methyl-1-phenylprop-1-en-1-amine.

Step 2