Let's break down each synthesis step-by-step, focusing on key organic chemistry concepts and possible reagents. --- ## (i) Synthesis ### **Starting Material:** - 4-methyl-1,3-cyclohexanedione ### **Target Compound:** - Bicyclic compound with a six-membered ring fused to a five-membered ring (likely a Robinson annulation product). ### **Key Reaction:** - **Robinson Annulation** (Michael addition + Intramolecular Aldol Condensation) ### **Synthesis Steps:** 1. **Michael Addition:** - React the starting material with methyl vinyl ketone (MVK). - The enolate from the starting material attacks the β-carbon of MVK. 2. **Intramolecular Aldol Condensation:** - The intermediate undergoes aldol condensation, forming the fused bicyclic system. - Dehydration produces the α,β-unsaturated ketone. **Summary Reaction:** ```markdown 4-methyl-1,3-cyclohexanedione + methyl vinyl ketone → (Michael Addition) → intermediate → (Aldol Condensation) → target fused bicyclic ketone ``` --- ## (ii) Synthesis ### **Starting Material:** - Benzene ### **Target Compound:** - 4-chloro-2-(methylamino)acetophenone ### **Key Reactions:** - **Friedel-Crafts Acylation** - **Chlorination** - **Amination (nucleophilic substitution)** ### **Synthesis Steps:** 1. **Friedel-Crafts Acylation:** - React benzene with acetyl chloride (CH₃COCl) and AlCl₃ to form acetophenone. 2. **Chlorination:** - Chlorinate acetophenone with Cl₂ (and FeCl₃ as catalyst) to introduce Cl at the para position. 3. **Nucleophilic Substitution:** - React the product with methylamine (CH₃NH₂) to replace the para hydrogen with a methylamino group via nucleophilic aromatic substitution. **Summary:** ```markdown Benzene → (Friedel-Crafts Acylation) → acetophenone → (Chlorination) → 4-chloroacetophenone → (Amination with CH₃NH₂) → target compound ``` --- ## (iii) Synthesis ### **Starting Material:** - Benzene ### **Target Compound:** - 1-bromo-4-chlorobenzene ### **Key Reactions:** - **Electrophilic Aromatic Substitution (EAS)** ### **Synthesis Steps:** 1. **Chlorination:** - Chlorinate benzene with Cl₂/FeCl₃ to get chlorobenzene. 2. **Bromination:** - Brominate chlorobenzene with Br₂/FeBr₃. Chlorine is an ortho/para-directing group, so bromine will go to the para position. **Summary:** ```markdown Benzene → (Chlorination) → chlorobenzene → (Bromination) → 1-bromo-4-chlorobenzene ``` --- ## **Summary Table** | Step | i. | ii. | iii. | |----------------------|-------------------------------|---------------------------------|--------------------------------| | 1 | Michael Addition | Friedel-Crafts Acylation | Chlorination | | 2 | Aldol Condensation | Chlorination | Bromination | | 3 | (Forms bicyclic ketone) | Nucleophilic Aromatic Subst. | (Forms 1-bromo-4-chlorobenzene)| Feel free to ask for detailed mechanisms or reagents for any specific step!