# How can the ketone in a β-ketoester be protected during hydride reduction?

I am supposed to find what X is. I know that $$\ce{LiAlH_4}$$ will convert all carbonyl groups to alcohols, and the ester group is being reduced. The only way of ending up with a ketone that I can think of is by a pinacol reaction.

However, the answer given was that X was $$\ce{HOCH2CH2OH + H+}$$. How does this work?

• en.wikipedia.org/wiki/Protecting_group Read the introduction paragraph, it is exactly the same as your question. – orthocresol Dec 9 '15 at 5:22
• That was helpful. – mathemather Dec 9 '15 at 5:24
• By the way, you could technically use any alcohol you wanted to protect the ketone, although ethylene glycol is probably a reliable choice since you get the stability of a 5-membered ring. Basically, the answer isn't unique. – orthocresol Dec 9 '15 at 5:42