Superacid-catalyzed reactions of cinnamic acids and the role of superelectrophiles.
The chemistry of cinnamic acids and related compounds has been studied. In superacid-catalyzed reactions with arenes, two competing reaction mechanisms are proposed. Both mechanisms involve the formation of dicationic intermediates (superelectrophiles), and the reactions can lead to either chalcone-type products or indanone products. The direct observation of a dicationic species (by low-temperature (13)C NMR) is reported. We provide clear evidence that protonated carboxylic acid groups (or the corresponding acyl cation) can enhance the reactivity of an adjacent electrophilic center. Triflic acid is also found to be an effective acid catalyst for the direct synthesis of some electron-deficient chalcones and heterocyclic chalcones from cinnnamic acids.
Rendy
Rendy
R
Department of Chemistry, California State Polytechnic University, 3801 West Temple Avenue, Pomona, California 91768, USA.
Zhang
Yun
Y
McElrea
Aaron
A
Gomez
Alma
A
Klumpp
Douglas A
DA
D000215:Acylation; D002264:Carboxylic Acids / Q000737:chemistry; D002384:Catalysis; D002599:Chalcone / Q000031:analogs & derivatives / Q000737:chemistry*; D002934:Cinnamates / Q000737:chemistry*; D004563:Electrochemistry; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008698:Mesylates / Q000737:chemistry; D015394:Molecular Structure
D002264:Carboxylic Acids; D002934:Cinnamates; D007202:Indicators and Reagents; D008698:Mesylates; C029010:cinnamic acid; D002599:Chalcone; C012077:trifluoromethanesulfonic acid