Q1(f). Phenol to a reduced aryl ether

Answer in brief

Use base followed by ethyl bromide for ether formation, then Na or Li in liquid NH₃ with an alcohol proton source for Birch reduction.

Key points

• Deprotonate phenol to phenoxide; its oxygen attacks ethyl bromide by SN2, displacing bromide and giving PhOEt.
• A solvated electron adds to the aromatic ring, giving a radical anion; protonation, a second electron transfer and a second protonation reduce two ring positions.
• The electron-donating OEt substituent remains on an unsaturated carbon in the major Birch product, 1-ethoxycyclohexa-1,4-diene.
• The product contains isolated double bonds; ordinary catalytic hydrogenation would not selectively produce this 1,4-diene.