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.