Selective oxidation and reduction of functional groups on benzene

Steps:

• Compound X is a benzene ring with -CHO (aldehyde) and -COCH3 (ketone) substituents.
• Mild oxidizing agent converts the aldehyde (-CHO) to carboxylic acid (-COOH), yielding Y with -COOH and -COCH3.
• NaBH4 then reduces the ketone (-COCH3) to a secondary alcohol (-CH(OH)CH3), leaving the -COOH unchanged, forming Z.
• Z is thus benzene with -COOH and -CH(OH)CH3.

Why A is correct:

• NaBH4 selectively reduces ketones to secondary alcohols via hydride addition to the carbonyl, but does not reduce carboxylic acids due to their lower reactivity.

Why the others are wrong:

• B: Implies reduction of -COOH to -CH2OH, which requires LiAlH4, not NaBH4.
• C: Same error as B, suggesting primary alcohol from carboxylic acid reduction.
• D: Matches A but likely a formatting duplicate; A is the intended correct structure.

Final answer: A