Chem 334 1nd Edition Lecture 18Outline of Last Lecture I. Reactions at the alpha carbon of carbonyl compoundsOutline of Current Lecture II. Enolates of Beta Dicarbonyl CompoundsIII. Acetoacetic Ester SynthesisIV. Malonic Ester SynthesisCurrent LectureEnolates of Beta Dicarbonyl Compounds: A. B. O O O H HMolecule B in the example above is much more acidic(lower pka) than molecule A, because the hydrogen is between two carbonyls. A hydrogen between 1,3 carbonyls would be even more acidic because it is surrounded by electron withdrawing carbonyls. It is more acidic because of the stabilized anion. Basically, it can share a negative charge between three different atoms, making it more stabilized.-OR/-OH now basic enough to fully deprotonate O O O O -O _ OH HWe can also use acetoacetic ester(one ketone and one ester), or z esters/diethyl malonate(two esters).Acetoacetic ester synthesis: O O -OEt O O O- O R–X O O -OEt O _ O O O R O O R–X O O NaOH O O H+ wkup O O Δ OThese 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 O Δ O- OH R R R R R R R R RR-X in this reaction can be a primary alkyl group, a primary benzylic or a primary allylic halides. It’s also possible to have stopped after just one alkyl addition.Remember that decarboxylation happens w/ carboxylic acids that have beta carbonyls. We need to change the base because we cannot use protic solvents. Therefore, we’ll use NaH instead. O O NaH O O OEt O OEt Cl OMalonic ester synthesis: O O 1. NaOEt O O 1. NaOHΔ O O Δ O O O 2. I O O 2. H+ OH OH OH These reactions are limited to the same primary electrophiles as the reactions
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