Chapter 24, Problem 24.26P

Interpretation Introduction

Interpretation: The bicyclic ring systems among the given systems that can be prepared by an intermolecular Robinson annulation are to be stated.

Concept Introduction: The combination of the Michael reaction and intramolecular aldol reaction in which the formation of a ring takes place is known as Robinson annulation reaction. In this reaction, the carbonyl compound is treated with a base which leads to the elimination of a proton from the $\text{α}-\text{carbon}$ atom. This elimination leads to the formation of an enolate ion. Then, this enolate ion acts as the nucleophile and undergoes conjugate addition reaction with the $\text{β}-\text{carbon}$ of the $\text{α},\text{β}-\text{unsaturated}$ carbonyl compound that results in the formation of the new carbon-carbon bond and the desired Robinson annulation product.