Question

Show how you would synthesize each compound from starting materials containing no more than six carbon atoms.

(a)

(b)

(c)

Short answer

(a)

(b)

(c)

Step-by-step solution

Reaction of Carbonyl Compound

Carbonyl compounds (aldehydes and ketones) reacts with RMgX to form alcohols as the major product. Aldehyde gives secondary alcohols whereas ketone gives tertiary alcohols.

Synthetic methodology

(a) 1-bromo cyclohexane is first treated with magnesium in the presence of ether to form grignard reagent (cyclohexylmagnesium bromide). The so formed grignard reagent undergoes hydrolysis to form an alcohol. Again, the alcohol is oxidised by PCC to form the target compound. The corresponding reactions are shown below.

(b) Benzene can be converted to propiophenone by Friedel Crafts acylation reaction. In this reaction, benzene combine with propanoyl chloride in the presence of Lewis acid AlCl₃ to form an aromatic ketone (propiophenone). The corresponding reaction is shown.

(c) 1-bromocyclopentane is first treated with magnesium in the presence of ether to form grignard reagent (cyclopentylmagnesium bromide). The so formed grignard reagent undergoes treatment with epoxide and subsequent hydrolysis to form an alcohol. Again, the alcohol is oxidised by PCC to form the target compound. The corresponding reactions are shown below.