42916-15-4Relevant academic research and scientific papers
Superacid-Catalyzed Reactions of Cinnamic Acids and the Role of Superelectrophiles
Rendy, Rendy,Zhang, Yun,McElrea, Aaron,Gomez, Alma,Klumpp, Douglas A.
, p. 2340 - 2347 (2004)
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 13C 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.
A comparative Study of the Decomposition of o-Alkynyl-Substituted Aryl Diazo Ketones. Synthesis of Polysubstituted β-Naphthols via Arylketene Intermediates
Padwa, Albert,Chiacchio, Ugo,Fairfax, David J.,Kassir, Jamal J.,Litrico, Angelo,at al.
, p. 6429 - 6437 (2007/10/02)
The photochemical, thermal, and rhodium-catalyzed decomposition reactions of several closely related o-alkynyl or o-alkenyl α-diazoaceto- and propiophenone derivatives have been studied.The reaction outcome is markedly dependent upon the reaction conditions employed for nitrogen extrusion.Thermolysis or photolysis of o-alkynyl α-diazopropiophenone derivatives yields polysubstituted β-naphthols.These products are derived from Wolff rearrangement of the initially formed carbene to give an aryl ketene which undergoes intramolecular cyclization onto the o-alkynylsubstituent.In direct contrast to the thermal and photochemical results, Rh(II)-catalyzed decomposition yields products derived from direct attack of a rhodium carbenoid onto the tethered ?-system producing a vinyl carbenoid intermediate.Further reaction of the cyclized carbenoid with the starting diazo compound furnished a vinyl indenone which undergoes a rapid intramolecular Diels-Alder reaction to produce a novel dimer whose structure was elucidated by an X-ray crystal analysis.Replacement of the methyl group on the diazo center with a sterically less demanding hydrogen atom was also found to play an important role in controlling the outcome of the Rh(II)-catalyzed reaction.
