Page numbers refer to Organic Chemistry third edition by Paula Yurkanis Bruice
This is an eight-step synthesis of 2-ethylpent-1-ene:
Step 1. First propyne is converted to 2-hexyne by reacting it with NaNH2 and 1-bromobutane.
Step 2. Na and NH3 (liq) are used to make 2-hexene from 2-hexyne.
Step 3. HBr reacts with 2-hexyne to form 3-bromohexane. In this step we lose half of the product because what actually forms are 3-bromohexane and 2-bromohexane—we only want the 3-bromohexane product.
Step 4. This reacts with R4N+, HSO-4 and –CN to form 2-ethylpentanenitrile.
Step 5. This then reacts with H+, Water and heat to form 2-ethylpentanoic acid.
Step 6. 2-ethylpentanoic acid reacts with LiAIH4 and then H+ and water to form 2-ethylpentan-1-ol.
Step 7. 2-ethylpentan-1-ol reacts with HBr and heat to form 3-(bromomethyl)hexane.
Step 8. Finally, 3-(bromomethyl)hexane reacts to form 2-ethylpent-1-ene.