NHC-catalyzed reactions of aryloxyacetaldehydes: a domino elimination/conjugate addition/acylation process for the synthesis of substituted coumarins.
N-heterocyclic carbenes (NHCs) catalyze a domino Michael addition/acylation reaction to form 3,4-dihydrocoumarins. The reaction proceeds through addition of the NHC to an aryloxyaldehyde followed by elimination of a phenoxide leaving group, generating an enol intermediate. This transient nucleophile generated in situ performs a 1,4-addition onto a conjugate acceptor, and the carbene catalyst is regenerated upon acylation of the phenoxide anion resulting in formation of 3,4-dihydrocoumarins.
Phillips
Eric M
EM
Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
Wadamoto
Manabu
M
Roth
Howard S
HS
Ott
Andrew W
AW
Scheidt
Karl A
KA
D000079:Acetaldehyde / Q000031:analogs & derivatives / Q000737:chemistry*; D002384:Catalysis; D003374:Coumarins / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D006571:Heterocyclic Compounds / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism
D003374:Coumarins; D006571:Heterocyclic Compounds; C030011:carbene; D000079:Acetaldehyde; D008697:Methane