Question

Question: Draw a stepwise mechanism for the conversion of neryl diphosphate to $\mathit{\alpha }\mathbf{-}\mathit{p}\mathit{i}\mathit{n}\mathit{e}\mathit{n}\mathit{e}$, $\mathit{\alpha }\mathbf{-}\mathit{p}\mathit{i}\mathit{n}\mathit{e}\mathit{n}\mathit{e}$is a component of pine oil and rosemary oil.

Short answer

Answer

A stepwise mechanism for the conversion of neryl diphosphate to $\alpha -pinene$is:

Step-by-step solution

Biosynthesis of terpenes and terpenoids

A diphosphate is a leaving group in the biosynthesis of terpenes and terpenoids.There are two main steps: one is forming a new sigma bond between two carbon atoms, and the other is forming a new pi bond.

Stepwise mechanism for the conversion of neryl diphosphate to  α-pinene

In the first step, diphosphate loss occurs, forming a resonance stabilized carbocation.

In the second step, a pi bond is formed by the proton loss (with a base B), forming a $\alpha -pinene$.

Stepwise mechanism