Question 31.41 - Organic Chemistry

Question

Farnesyl diphosphate is cyclized to sesquiterpene A, which is then converted to the bicyclic product epi-aristolochene. Write a stepwise mechanism for both reactions.

Step-by-Step Solution

Answer

Answer

The mechanism of the reaction

Step 1: About farnesyl diphosphate

The commonly used intermediate used for the biosynthesis of terpenes, sterols, terpenoids, carotenoids, etc., is farnesyl diphosphate. 

 

This compound is also used in the synthesis of the part present in the electron transport chain known as CoQ.

Step 2: About epi-aristolochene

The formed product epi-aristolochene is an enzyme. This compound is mainly used in the plant metabolite. This compound exists naturally in the Nicotiana tabacum. This compound is a member of octa hydro naphthalenes.

Step 3: About the mechanism

The given starting material is rearranged and written similarly to the cyclic form. The OPP is removed, and the cation is obtained, which is resonance stabilized. Then it is treated with an acid that leads to the formation of a cation. 

 

Then it is subjected to a 1,2 H shift followed by $1,2-{\mathrm{CH}}_3$ shift. On rearrangement, the final product is obtained. The mechanism is shown below.

The mechanism of the reaction