Question

Assume general laboratory reagents and butadiene are available.
Which of the following sequences could accomplish the following synthesis?

• A. 1: Dissolved metal reduction of butadiene;
  2; Catalytic hydrogenation
• B. 1: Kolbe's electrolysis;
  2; Catalytic hydrogenation
• C. 1: Stephen's aldehyde synthesis;
  2; Catalytic hydrogenation
• D. 1: Diels-Alder of butadiene and the substrate;
  2; Catalytic hydrogenation

Answer 1

The correct option is D 1: Diels-Alder of butadiene and the substrate;

2; Catalytic hydrogenation

Observe the stereochemical data on either side of the equation – both Cl and COOH groups remain trans;
This points to a nifty implementation of the Diels-Alder reaction:


The product from above on catalytic hydrogenation completes the synthesis.
Watch the video for more on the Diels-Alder reaction – a reaction that won
the scientist duo Otto Diels and Kurt Alder a Nobel prize in Chemistry in 1950.