Favorskii Rearrangement Concepts

The video tutorial covers the Favorskii rearrangement, a reaction that induces ring contraction, invented by Alexei Favorskii in 1894. It primarily applies to enolizable alpha-chloro ketones and is used in synthesis for ring contraction. The mechanism involves enolate formation, cyclopropanone intermediate, and carboxylic acid formation. Variations include using alpha-bromo ketones and anhydrous alkoxides. Symmetry in intermediates is confirmed through 14C labeling. Applications include synthesizing strained systems like cubane and epibatidine. The Favorskii rearrangement remains a valuable tool in organic synthesis.

Who invented the Favorskii rearrangement?

• Dmitri Mendeleev

• Alexei Favorskii

• Linus Pauling

• Marie Curie

What is the primary application of the Favorskii rearrangement in synthesis?

• Ring expansion

• Ring contraction

• Oxidation

• Polymerization

In the Favorskii rearrangement, what intermediate is formed after the enolate attacks the carbon bearing the chloro group?

• Cyclopentanone

• Cyclobutanone

• Cyclohexanone

• Cyclopropanone

What happens to the cyclopropanone intermediate in the Favorskii rearrangement?

• It is stable and can be isolated

• It forms a stable dimer

• It is attacked by hydroxide base

• It undergoes a Diels-Alder reaction

In a non-symmetrical system, how does the ring open in the Favorskii rearrangement?

• To yield a radical

• To yield a symmetrical carbanion

• To yield the less substituted carbanion

• To yield the more substituted carbanion

What is a key feature of the Favorskii rearrangement mechanism?

• It only works with symmetrical ketones

• It yields the same carboxylate from isomeric alpha-haloketones

• It requires a metal catalyst

• It yields different carboxylates from isomeric alpha-haloketones

What happens when anhydrous alkoxides are used as bases in the Favorskii rearrangement?

• Alcohols are formed

• Esters are formed

• Aldehydes are formed

• Carboxylate salts are formed

What does the 14C labeling experiment confirm about the Favorskii rearrangement?

• The reaction is stereospecific

• The cyclopropanone can open both ways with equal probability

• The intermediate is not symmetrical

• The reaction does not involve cyclopropanone

Which famous synthesis utilized the Favorskii rearrangement for a ring contraction?

• Synthesis of cubane

• Synthesis of penicillin

• Synthesis of nylon

• Synthesis of aspirin

What is the final product in the synthesis of epibatidine using the Favorskii rearrangement?

• A mixture of epibatidine and its isomers

• A pure enantiomer of epibatidine

• A polymer of epibatidine

• A racemic mixture of epibatidine