Carbonyl Alpha-Substitution Reactions (Enols and Enolates, Malonic Ester Syn, Stork)

Problem # 749

Show how to prepare each compound below from propanal. I've marked the "cuts" for you.

Problem # 748

Alpha bromination is usually carried out under acidic conditions via the enol intermediate. 

Alpha bromination is uncontrollable under basic conditions, which goes through the enolate intermediate. Let's explore why.



a) Rank each carbonyl below in order of decreasing alpha-proton acidity (1= most acidic). Explain.

b) based on a), why does the reaction below lead to polyhalogenation?