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Direct amination of homoenolates catalyzed by N-heterocyclic carbenes.

ABSTRACT: N-Heterocyclic carbenes derived from N-mesityl-N-methyltriazolium salts are effective catalysts for generating homoenolate species from alpha,beta-unsaturated aldehydes. The unique intermediate adds to the electrophilic nitrogen of 1-acyl-2-aryldiazenes, and the resulting activated carbonyl unit undergoes an intramolecular acylation event. This formal [3+2] cycloaddition between alpha,beta-unsaturated aldehydes and acylaryldiazenes, catalyzed by an N-heterocyclic carbene, produces substituted pyrazolidinones in good yields. This new NHC-catalyzed reaction accommodates aromatic and alkyl alpha,beta-unsaturated aldehydes and various aromatic diazenes. A chiral triazolium salt catalyzes the formation of the pyrazolidinone product in moderate yield and good enantioselectivity. The pyrazolidinones can undergo reductive N-N bond cleavage to give beta-amino acid derivatives.

SUBMITTER: Chan A

PROVIDER: S-EPMC2981089 | biostudies-literature | 2008 Mar

REPOSITORIES: biostudies-literature

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Direct amination of homoenolates catalyzed by N-heterocyclic carbenes.

Chan Audrey A Scheidt Karl A KA

Journal of the American Chemical Society 20080209 9

N-Heterocyclic carbenes derived from N-mesityl-N-methyltriazolium salts are effective catalysts for generating homoenolate species from alpha,beta-unsaturated aldehydes. The unique intermediate adds to the electrophilic nitrogen of 1-acyl-2-aryldiazenes, and the resulting activated carbonyl unit undergoes an intramolecular acylation event. This formal [3+2] cycloaddition between alpha,beta-unsaturated aldehydes and acylaryldiazenes, catalyzed by an N-heterocyclic carbene, produces substituted py ...[more]

PMID: 18260665

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