Chapter 22- important concept

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Chapter 22- important concept.
Reactions: you should know the following reactions, and also be able to draw the
mechanism (acid and/or base catalyzed):
-
halogenation
haloform reaction
HVZ reaction
 alkylation of ketones (via LDA, or by enamine formation)
aldol condensation of ketones and aldehydes, followed by dehydration
crossed aldol condensation (pay attention to the best strategy to minimize unwanted
products))
Claisen condensation of esters, crossed Claisen and intramolecular (Dieckmann)
Malonic ester synthesis of substituted acids
Acetoacetic ester synthesis of substituted ketones
Michael addition (enolate to  unsaturated ketones)
Robinson annulation
Things to remember: the first step in an acid catalyzed mechanism is always the
protonation of the carbonyl, and in a base catalyzed reaction it’s the abstraction of a 
proton to form an enolate.
Acidity of  protons: ketones (pKa~20) are more acidic than eters (pKa~24), 1,3
dicarbonyl compounds are more acidic (pKa~10), with diketones > ketoesters > diesters.
Also, try to focus on the products formed in each reaction, and to the C-C bonds formed.
For example,  substituted ketones can be made by direct alkylation of a ketone (using
LDA as base, or activating the carbonyl via enamine formation) with an alkyl halide (SN2
mechanism), or by acetoacetic ester synthesis (alkylation of a 1,3 (or ) ketoester
followed by acid hydrolysis (heat));
 substituted acids can be made by malonic ester synthesis (alkylation of a 1,3 (or )
diester followed by acid hydrolysis (heat));
1,5 (or ) diketones and ketoesters can be made by Michael addition of an enolate,
typically a 1,3 (or  dicarbonyl compound, to a  unsaturated ketone or aldehyde;
in turn,  unsaturated ketones or aldehydes can be made by aldol condensation.
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