Palladium-Catalyzed Carbonylation Reaction of Aryl Bromides with 2-Hydroxyacetophenones to Form Flavones
作者:Xiao-Feng Wu、Helfried Neumann、Matthias Beller
DOI:10.1002/chem.201202141
日期:2012.10.1
Flavone of the month: A general and efficient method for the palladium‐catalyzed carbonylativesynthesis of flavones has been developed (see scheme). Starting fromarylbromides and 2‐hydroxyacetophenones, the corresponding flavones have been isolated in good yields.
Pd–carbene catalyzed carbonylation reactions of aryl iodides
作者:Liqin Xue、Lijun Shi、Yuan Han、Chungu Xia、Han Vinh Huynh、Fuwei Li
DOI:10.1039/c1dt10433k
日期:——
A series of carbene complexes [PdBr2(iPr2-bimy)L] (C2âC13) with different types of co-ligands (L) have been tested for their catalytic activities in the carbonylative annulation of 2-iodophenol with phenylacetylene in DMF to afford the respective flavone 2a. Complex C12 with an N-phenylimidazole co-ligand showed the best activity and also afforded high yields when the substrate scope was extended to other aryl or pyridyl acetylenes. In addition, catalyst C12 was also efficient in the carbonylative annulation of 2-iodoaniline with acid chlorides giving the desirable 2-substituted 4H-3,1-benzoxazin-4-ones (4) in good yields. Additionally, this PdâNHC complex also proved to be a very efficient catalyst for the hydroxycarbonylation of iodobenzene derivatives at low catalyst loading and under low CO pressure. These results demonstrate the versatility and efficiency of this phosphine-free Pd(II)âNHC complex in different types of carbonylations of aryl iodides under mild conditions.
Es wird gezeigt, dass man durch Kondensation von basisch substituierten Estern mit o-Oxy-acylphenonen und Ringschluss der entstandenen 1,3-Diketone zu Chromonen gelangt, die in 2-Stellung basisch substituiert sind. Die Synthese liess sich auch mit N-acetylierten Estern durchführen.
An efficient oxidative conversion of 2-aryl-2H-chromenes to the corresponding flavones by tert-butylhydroperoxide and copper bromide
作者:Dipanwita Banerjee、Utpal Kayal、Gourhari Maiti
DOI:10.1016/j.tetlet.2016.03.006
日期:2016.4
A simple and efficient method has been developed for the facile oxidation of chromenes to the corresponding flavones by tert-butylhydroperoxide (TBHP) in the presence of copper(II) bromide catalyst in toluene at 80 °C in a very short time. The reaction demonstrates excellent reactivity, functional group tolerance, and good to excellent yields without using conventional strong oxidizing agents.
Pyrrolidine and iodine catalyzed domino aldol-Michael-dehydrogenative synthesis of flavones
作者:Mayuri M. Naik、Santosh G. Tilve、Vijayendra P. Kamat
DOI:10.1016/j.tetlet.2014.04.051
日期:2014.5
A one pot synthesis of flavones is established from 2′-hydroxyacetophenones and substituted aromatic aldehydes. The method uses domino aldol-Michael-oxidation reactioncatalyzed by pyrrolidine as a base and iodine as an oxidant in dimethyl sulfoxide.