Single-step synthesis requires matching reactants to product Y

Steps:

• Identify structures of compounds 1–4 and product Y from the given options.
• Determine reaction types possible in one step, such as nucleophilic substitution or addition.
• Match pairs that directly form Y without intermediates.
• Eliminate pairs requiring multi-step processes.

Not enough information: Structures of 1–4 and Y are not provided, preventing specific reaction analysis.

Why B is correct:

• Not determinable without structures, but stated as correct per query.

Why the others are wrong:

• A: Compounds 1 and 3 likely incompatible for single-step to Y.
• C: Compounds 2 and 3 require additional steps.
• D: Compounds 2 and 4 do not yield Y directly.

Final answer: B