Aromatic Hydrocarbon

To solve the problem, we need to identify the aromatic compound or species with the maximum number of π-electrons.

1. Review of π-electrons in Aromatic Compounds:
Aromaticity is explained using Huckel’s Rule: a compound is aromatic if it has π-electrons (where is an integer). The number of π-electrons is typically counted from the number of conjugated double bonds in a planar cyclic system.

2. Count π-electrons in Each Option:

• Phenanthrene: Contains three fused benzene rings → 3 rings × 6 π-electrons = 18 π-electrons
• Naphthalene: Contains two fused benzene rings → 2 rings × 6 π-electrons = 10 π-electrons
• Cyclopentadienyl anion: 5-membered ring with 6 π-electrons (aromatic, but fewer electrons)
• Cycloheptatrienyl cation (tropylium): 7-membered ring with 6 π-electrons (aromatic, but again fewer electrons)

3. Comparison:
Among all the given options, Phenanthrene has the highest number of delocalized π-electrons (18).

Final Answer:
The aromatic compound with the maximum number of π-electrons is Phenanthrene.

The sequence of reactions starts with a base-promoted elimination, followed by a rearrangement and a substitution to finally produce the ester as the end product.