Chapter 7.SE, Problem 33MP

Interpretation Introduction

Interpretation:

The mechanism for each step in the pathway given for bio synthesizing epi-Aristolochene is to be shown using curved arrows. Further the steps that involve electrophilic addition(s) to the alkene and that involve carbocation rearrangement(s) are to be identified.

Concept introduction:

While drawing curved arrows the head of the curved arrow starts from the nucleophilic source (either negatively charged or neutral) and ends in an electrophilic sink (either positively charged or neutral). The formation of a new bond should lead to the breaking of a bond that already exists as the octet rule cannot be violated.

In electrophilic addition reactions, the first step is the attack of the π electrons of the double bond on the hydrogen of another reactant to yield a carbocation. One of the carbon in C=C gets attached to hydrogen while the other acquires a positive charge. In the second step, the carbocation formed can rearrange to give another more stable carbocation either by a hydride shift (shift of hydrogen atom with its electron pair) or by an alkyl shift (shift of an alkyl group with its electron pair) between neighboring carbons. In the last step the carbocation produced reacts with a negatively charged ion or eliminates a proton to give the product.

To show:

The mechanism for each step in the pathway given for bio synthesizing epi-aristolochene using curved arrows. Further to identify the steps that involve electrophilicaddition(s) to the alkene and that involve carbocation rearrangement(s).