Chapter 23, Problem 39DSP

Interpretation Introduction

Interpretation:

The most reasonable structure for compound 3 in the given reaction sequence is to be chosen.

Concept introduction:

Substituents attached to an aromatic ring promote metalation and control its regioselectivity.

Metalation usually takes place at the carbon atom ortho to the substituent.

Metalation can occur at C-2 of a 1, 3-disubstituted benzene as steric effects are insignificant in this case.

Directed metalation reactions are regioselective and occur at the carbon atom ortho to the acetal substituent.