Chem 334 1nd Edition Lecture 19Outline of Last Lecture I. Enolates of Beta carbonyl compoundsOutline of Current Lecture II. Enamine ReactionsIII. EnolatesIV. Aldol ReactionsCurrent LectureEnamine reactions:Formation of Enamines: O H+ N Deprotonate N NEnamines react with primary alkyl halides, primary benzylic halides, primary allylic halides, acid chlorides, anhydrides, alpha halo-ketones, and alpha halo-esters.Condensation and conjugate addition reactions of carbonyl compounds:Enolates:Enolates are nucleophiles, and so far they have been used in mainly SN2 reactions. Addition reactions with enolates: O- O O OH H Ph PhAldol reactions are very common enolate reactions. The basic mechanism of this reaction(below) is the most common. O NaOH O OH H HAcidic mechanism:These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.O HCl O OH H HAldol products can react further with dehydration(minus an H2O). Under the base catalyzed mechanism, we need heat in order to do this: O OH Δ O H H -OH H There is a beta unsaturated carbonyl between alpha and beta position to the carbonyl there is a double bond. Dehydration is easier under acidic conditions.So far, our enolate and electrophile have been the same. So how do we use different compounds? If we use an electrophile with no alpha hydrogens, no enolate can form. Use a ketone as the nucleophile. Ketones are poor electrophiles because they are too sterically hindered. O- O O
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