Chapter 18, Problem 18.10P

Interpretation Introduction

Interpretation: The stepwise mechanism for the intramolecular Friedel–Crafts acylation of compound $A$ to form $B$ is to be drawn.

Concept introduction: The Friedel-Craft acylation is a type of electrophilic substitution reaction. ${\text{AlCl}}_{\text{3}}$ is used as Lewis acid which ionizes the carbon-halogen bond of the acid chloride and forms a positively charged carbon electrophile which is resonance stabilized. Then the electrophile reacts with benzene.