Organic Chemistry : Help with Aldol Condensation
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Example Question #651 : Organic Chemistry
Determine the major product of the given intramolecular aldol reaction.
IV
I
II
None of these
III
II
Keep in mind the following principles: Cyclization is favored when a five/six-member ring may be formed. Addition at an aldehyde is favored relative to the same reaction at a ketone.
As a result, abstraction of a hydrogen bound to carbon 6 (an alpha-carbon) is favored since the resulting carbanion may attack the aldehyde (carbon 1) to form a six-member ring, resulting in compound II. Compound I results from abstracting a hydrogen from carbon 2, generating a carbanion which may then attack the ketone. Based on the latter of the above principles, this is a minor product.
Example Question #1 : Carbonyl Reactions
What is the final organic product of the reaction shown?
V
II
I
IV
III
I
First step: Friedel-Crafts acylation of benzene
Second step: Formation of enolate
Third step: aldol addition (enolate attacks carbonyl carbon in benzaldehyde)
Fourth step: neutralization of anion and dehydration forming alkene
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