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Nazarov Cyclization

Nazarov cyclization   Named Reactions in Organic Synthesis

Reaction category:
Pericyclic and photochemical reactions

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In 1941 the Russian chemist Ivan Nikolaevich Nazarov extensively studied the cyclization reactions of allyl vinyl ketones to the corresponding 2-cyclopentanones. Although cyclizations following this general procedure had been observed before Nazarov's work, it was his study of the rearrangements of allyl vinyl ketones that marked the first close examination of this process. Nazarov correctly reasoned that the allylic olefin isomerized in situ to form a divinyl ketone before ring closure to the cyclopentenone product. Subsequently the protic or Lewis acid catalysed ring-closure of divinyl ketones through formation of the corresponding pentadienylic cations became known as the Nazarov cyclization.

This reaction became useful in organic synthesis due to the frequent appearance of cyclopentanone ring in natural products and in the formation of synthetic intermediates in total synthesis campaigns.

For example in the synthesis of (±)-trichodiene by K.E. Harding and colleagues the Nazarov cyclization was employed as a key ring-forming step to control the stereochemistry.

 

Mechanism of the Nazarov cyclization:

mechanism of Nazarov Cyclization

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Other reaction categories:

Electrophilic aromatic substitution

Nucleophilic substitution reactions

Heterocycle-formation

Transition metal-catalyzed couplings

Oxidation

Reactions involving carbonyl compounds

Reduction reactions

Rearrangement reactions

Electrophilic addition reactions


Some relevant Alfa Aesar products for the Nazarov cyclization:

Acetic anhydride, 99+%
Acetic anhydride, ACS, 97+%
Sulfuric acid, ACS, 95.0-98.0%
Sodium hydroxide, pellets, 98%
Sodium hydroxide, flake, 98%
Boron trifluoride diethyl etherate, 98+%
Boron trifluoride diethyl etherate, 46.5% BF3 min, packaged under Argon in resealable ChemSeal™ bottles

 

 

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