Consider the following reaction sequence: Identify the major final product (Y).

Step-by-step solution

Reaction with AlCl₃ generates an electrophilic acylium ion from the acid chloride. The benzene ring undergoes an intramolecular Friedel-Crafts acylation. The alkyl chain is ortho/para-directing and activating, while the formyl ( -CHO ) group is meta-directing and deactivating. Since they are para to each other, their directing effects reinforce each other, directing the acylium ion to the position ortho to the alkyl chain. Cyclization at this position forms a fused six-membered ring, resulting in intermediate (X).