Q22-64E - Organic Chemistry (Mcmurry)

Question

The key step in a reported laboratory synthesis of sativene, a hydrocarbon isolated from the mold Helminthosporium sativum, involves the following base treatment of a keto tosylate. 

What kind of reaction is occurring? How would you complete the synthesis?

Step-by-Step Solution

Answer

The reaction which is occurring is alkylation first and then Wittig's reaction occurs.

Step 1:

The key step in a reported laboratory synthesis of sativene is the removal of 𝛂- hydrogen atom by the attack of base and the removal of the tosylate group:

 

Step 2: With the help of the Wittig reaction, we can synthesize Sativene:

The attack of methylene triphenyl phosphorane (PPh3CH₂)at carbonyl carbon:

 

                                                                     Sativene