Breslow intermediate
E601252
The Breslow intermediate is a reactive enaminol species proposed in organocatalysis that explains the umpolung (polarity inversion) of aldehydes in N-heterocyclic carbene-catalyzed reactions.
Statements (47)
| Predicate | Object |
|---|---|
| instanceOf |
enaminol
ⓘ
organic chemical species ⓘ reaction intermediate ⓘ |
| explains | umpolung of aldehydes ⓘ |
| field |
organocatalysis
ⓘ
physical organic chemistry ⓘ reaction mechanism analysis ⓘ |
| formedBy |
addition of N-heterocyclic carbene to aldehyde carbonyl
ⓘ
subsequent proton transfer and tautomerization to an enaminol ⓘ |
| hasAlternativeName |
Breslow enaminol
ⓘ
NHC-bound enaminol intermediate ⓘ |
| hasComponent |
alpha-carbon bearing partial negative character
ⓘ
conjugated C=C–C=O system ⓘ enol hydroxyl group ⓘ |
| hasElectronicEffect | inverts electrophilic carbonyl carbon to nucleophilic center ⓘ |
| hasPrecursor |
N-heterocyclic carbene
ⓘ
aldehyde ⓘ |
| hasProperty |
can be stabilized in some systems for spectroscopic observation
ⓘ
highly reactive ⓘ nucleophilic at the former carbonyl carbon ⓘ often not directly observable ⓘ results from polarity inversion of aldehyde carbonyl ⓘ transient ⓘ |
| hasRole |
key intermediate in N-heterocyclic carbene catalysis
ⓘ
nucleophilic acyl anion equivalent ⓘ umpolung reagent ⓘ |
| isPartOf |
mechanism of Stetter reaction
ⓘ
mechanism of benzoin condensation ⓘ |
| mechanisticRole |
central intermediate in organocatalytic umpolung chemistry
ⓘ
connects N-heterocyclic carbene addition to aldehyde with acyl anion reactivity ⓘ |
| namedAfter | Ronald Breslow NERFINISHED ⓘ |
| occursIn | N-heterocyclic carbene organocatalytic cycles ⓘ |
| participatesIn |
N-heterocyclic carbene-catalyzed Stetter reaction
ⓘ
N-heterocyclic carbene-catalyzed acylation reactions ⓘ N-heterocyclic carbene-catalyzed benzoin condensation ⓘ N-heterocyclic carbene-catalyzed umpolung reactions of aldehydes ⓘ |
| proposedBy | Ronald Breslow NERFINISHED ⓘ |
| proposedIn | 1950s ⓘ |
| relatedTo |
N-heterocyclic carbene
ⓘ
Stetter reaction NERFINISHED ⓘ acyl anion equivalent ⓘ benzoin condensation ⓘ umpolung ⓘ |
| stabilizedBy |
conjugating substituents on the aldehyde
ⓘ
electron-withdrawing substituents on the N-heterocyclic carbene ⓘ |
| usedAsConceptIn |
design of new N-heterocyclic carbene catalysts
ⓘ
development of umpolung-based synthetic methods ⓘ |
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.