Which pair of esters is most likely to provide a useful Claisen synthesis?

Question

Quizplus · Accepted Answer

Ethyl ethanoate and ethyl oxalate are the best choice for a Claisen synthesis because they have the necessary leaving groups (ethyl and methoxycarbonyl) and the difference in acidity between the alpha-carbon and beta-carbon is large enough to facilitate the Claisen condensation reaction. The other options either lack appropriate leaving groups or have too small of a difference in acidity between the alpha-carbon and beta-carbon for an efficient Claisen synthesis.

Which Pair of Esters Is Most Likely to Provide a Useful