16108-51-3Relevant articles and documents
An efficient TBHP/TBAI-mediated protocol for the synthesis of 4H-chromen-4-ones from chroman-4-ones via oxidative C–C bond formation
Agisho, Habtamu Abebe,Hairat, Suboot,Zaki, Mehvash
, p. 599 - 603 (2020/05/04)
Abstract: A transition metal-free and efficient TBHP/TBAI-mediated protocol has been developed for the synthesis of 4H-chromen-4-ones from chroman-4-ones via oxidative C–C bond formation. It proceeds in the presence of a catalytic amount of tetrabutylammonium iodide and oxidant tert-butyl hydroperoxide (TBHP, 5–6 M in decane) to afford the corresponding products in good to excellent yields. Furthermore, it has been observed that an increase in the concentration of TBHP to 30 mol % drastically increases the yield of 4H-chromen-4-ones, any further increase will lead to a decrease in percent yield. The mechanism of this reaction involves the generation of tertiary butoxide radical initially which by oxidative single-electron transformation is converted to iodochroman-4-one. Later the hydrogen iodide is removed from iodochroman-4-one to give the desired product, i.e. 4H-chromen-4-ones. Moreover, this is a rare example of the n-Bu4NI/TBHP-mediated C–C bond through dehydrogenative reaction. Graphic abstract: [Figure not available: see fulltext.]
Synthesis of chiral chromanols: Via a RuPHOX-Ru catalyzed asymmetric hydrogenation of chromones
Ma, Yujie,Li, Jing,Ye, Jianxun,Liu, Delong,Zhang, Wanbin
supporting information, p. 13571 - 13574 (2019/01/05)
Chiral chromanols and their derivatives have been synthesized via a RuPHOX-Ru catalyzed asymmetric hydrogenation of chromones in high yields, >20:1 drs and with up to 99.9% ee. Control experiments show that the reaction undergoes two sequential asymmetric hydrogenation steps of the CC and CO double bonds. The reaction could be performed on a gram-scale with a relatively low catalyst loading (up to 1000 S/C), and the resulting products can be transformed to several biologically active compounds.
Ruthenium-NHC-catalyzed asymmetric hydrogenation of flavones and chromones: General access to enantiomerically enriched flavanones, flavanols, chromanones, and chromanols
Zhao, Dongbing,Beiring, Bernhard,Glorius, Frank
supporting information, p. 8454 - 8458 (2013/09/02)
Two to four! Readily available flavones and chromones were efficiently converted into four valuable chiral classes of O-heterocycles - flavanones, chromanones, flavanols, and chromanols - by means of an enantioselective Ru/NHC-catalyzed hydrogenation process (see scheme; NHC=N-heterocyclic carbene, PCC=pyridinium chlorochromate). Copyright
Tandem reactions leading to bicyclic pyrimidine nucleosides and benzopyran-4-ones
Fan, Xuesen,Wang, Yangyang,Qu, Yingying,Xu, Haiyun,He, Yan,Zhang, Xinying,Wang, Jianji
, p. 982 - 985 (2011/03/22)
A novel, rapid, and efficient synthesis of bicyclic pyrimidine nucleosides and benzopyran-4-ones through oxidation of homopropargyl alcohols and subsequent isomerization, intramolecular addition of enol to allenic ketone has been developed. This methodology provides an efficient and promising approach to the structurally and pharmaceutically interesting pyrano[2,3-d]pyrimidine-2,5-dione nucleoside and benzopyran-4-one derivatives.
Benzopyrans : Part 40 - Alumina mediated transformations of 4-oxo-4H-1- benzopyran-3-carbaldehyde, -3-carboxylic acid and their 2-methylhomologues
Ghosh, Chandra Kanta,Bhattacharyya, Samita
, p. 166 - 172 (2007/10/03)
In contact with alumina, the title aldehyde 1 (R = H, Me, Cl) gives the chromones 5 and 9,12 whereas the acid 2 affords the chromones 7, 10 and acetophenone 23. Alumina converts the aldehyde 3 to the xanthone 14, and the corresponding acid 4 to the chromone 8 and diketone 24.
New photochemical approaches to the synthesis of chromones
Alvaro, Mercedes,Garcia, Hermenegildo,Iborra, Sara,A. Miranda, Miguel,Primo, Jaime
, p. 143 - 148 (2007/10/02)
Irradiation of the p-methoxyphenyl and p-methylphenyl esters of 2-butynoic, propynoic, 3-(ethylenedioxy)butanoic, 3,3-dimethoxypropanoic and 3-oxobutanoic acids (1-3) affords the corresponding photo-Fries products 4-6. Compound 5a is converted in part into the acetophenone 7a, by way of a Norrish type II photo-reaction, while compound 6a is reluctant to undergo this process, in spite of the fact that it also possess γ-carbonyl hydrogen atoms. From the preparative point of view, the photorearrangement of the esters 1a-d and 2a,c-d is exploitable, while that of 3a proceeds with a lower yield. The differences found in the photochemical behaviour of 2a and 3a show the sharp influence of the acetal group on the course of the reaction. Compounds 4-6 are representative model compounds valuable as direct chromone precursors; in fact, they can be readily cyclized to the chromones 10 under basic or acidic conditions.
Photolysis of Enol Acetates and α-Bromo Derivatives of o-(Acyloxy)acetophenones
Garcia, Hermenegildo,Martinez-Utrilla, Roberto,Miranda, Miguel A.
, p. 589 - 598 (2007/10/02)
UV irradiation of enol acetates 3a-g in benzene gives mainly o-(acetoxy)acetophenones 2 and 2-methylchromones 4. Under the same conditions, the dimethyl derivatives 3h and 3i remain unaffected.The α-bromo ketone 5a gives rise to mixtures of o-(acetoxy)acetophenone (2a), the diketone 6, and/or α-acetoxy-o-hydroxyacetophenone (7), depending on the irradiation conditions.The similarities and differences between the two series of experiments, as well as their possible mechanistic implications, are discussed.
PHOTOCYCLIZATION OF ENOL ACETATES OF o-ACETOXYACETOPHENONES TO CHROMONES
Garcia, Hermenegildo,Martinez-Utrilla, Roberto,Miranda, Miguel Angel
, p. 1749 - 1750 (2007/10/02)
Enol acetates of o-acetoxyacetophenones give chromones upon irradiation with uv-light.
