29976-75-8Relevant articles and documents
Palladium-catalyzed synthesis of flavones and chromones via carbonylative coupling of o-iodophenols with terminal acetylenes
Kalinin,Shostakovsky,Ponomaryov
, p. 4073 - 4076 (1990)
o-Iodophenols react with terminal acetylenes under carbon monoxide in the presence of palladium catalyst to give flavones or 2-substituted chromones.
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.]
Thermally regulated molybdate-based ionic liquids toward molecular oxygen activation for one-pot oxidative cascade catalysis
Song, Zhibin,Huang, Wei,Zhou, Yan,Tian, Zi-Qi,Li, Zhang-Min,Tao, Duan-Jian
, p. 103 - 109 (2020/01/21)
One-pot oxidative cascade catalysis plays a central role in the synthesis of key pharmaceutical and industrial molecules. Although ionic liquids are one of the most promising solvents and reaction media, the breakthrough of their catalysis in aerobic oxidation is very challenging due to the difficulty in the direct activation of molecular oxygen. Herein, a family of novel thermally regulated molybdate-based ionic liquids (Mo-ILs) has been designed and developed for the first time toward molecular oxygen activation for highly efficient tandem oxidative catalysis. Three diverse one-pot oxidative cascade processes for the syntheses of various flavones, imines, and benzyl benzoates were achieved with good to excellent yields using the Mo-IL [Bmim]2[MoO4] as a catalyst under air conditions. The results of spectroscopic investigations and quantum-chemical calculations further demonstrated that a thermally regulated proton migration between the cation [Bmim] and anion [MoO4] was the key to forming N-heterocyclic carbene and thereby to effortlessly promoting the generation of O2- active species from molecular oxygen, which results in excellent catalytic performance in these three aerobic tandem oxidations. Our work extends the application area of ILs as the sole catalyst to one-pot aerobic oxidative cascade catalysis, which could have pronounced implications in future work.
