4217-62-3Relevant academic research and scientific papers
A novel photodimerization of 4-aryl-4H-pyrans for cage compounds
Xin, Hongxing,Zhu, Xiaohe,Yan, Hong,Song, Xiuqing
, p. 3325 - 3328 (2013)
Irradiation of 4-aryl-4H-pyrans in either the solid state or in solution gave rise to the formation of novel oxa-cage compounds, 3,9-dioxatetraasteranes, derived from a double [2 + 2] cycloaddition reaction. Meanwhile, an unexpected oxetane formed by the Paternò-Büchi reaction of benzophenone with the pyrans, was established by 1H NMR data as well as by X-ray crystallographic analysis. Experimental observations and theoretical calculations confirmed that the photodimerization was effectively catalyzed by the triplet excited state of benzophenone, while the Paternò-Büchi reaction was competitive with the process.
Multiple-photon chemistry in the benzophenone photoreduction during laser-jet photolysis: Effect of alcohol solvent on cross-coupling versus hydrogen abstraction of the electronically excited hydroxydiphenylmethyl radical
Adam, Waldemar,Walther, Barbara
, p. 10399 - 10404 (1996)
The ground state of the hydroxydiphenylmethyl radical (1) leads to benzpinacol (2) through head-to-head coupling and the diols 3 as cross-coupling product. In contrast, under the high-intensity conditions of the laser-jet photolysis, the excited radical 1* couples in the para position to afford the benzophenone derivatives 4 (head-to-tail coupling) (higher spin density at the para position/AM1 calculations). The major two-photon product is benzhydrol (5). The pronounced increase in hydrogen atom abstraction from MeOH to iPrOH by 1* is explained in terms of the greater electrophilic character of the electronically excited radical 1* versus its ground state.
Iodine-Initiated Dioxygenation of Aryl Alkenes Using tert-Butylhydroperoxides and Water: A Route to Vicinal Diols and Bisperoxides
Gao, Xiaofang,Lin, Jiani,Zhang, Li,Lou, Xinyao,Guo, Guanghui,Peng, Na,Xu, Huan,Liu, Yi
, p. 15469 - 15480 (2021/11/16)
An environment-friendly and efficient dioxygenation of aryl alkenes for the construction of vicinal diols has been developed in water with iodine as the catalyst and tert-butylhydroperoxides (TBHPs) as the oxidant. The protocol was efficient, sustainable, and operationally simple. Detailed mechanistic studies indicated that one of the hydroxyl groups is derived from water and the other one is derived from TBHP. Additionally, the bisperoxides could be obtained in good yields with iodine as the catalyst, Na2CO3 as the additive, and propylene carbonate as the solvent, instead.
GaN nanowires as a reusable photoredox catalyst for radical coupling of carbonyl under blacklight irradiation
Botton, Gianluigi,Cen, Yunen,Cheng, Shaobo,Li, Chao-Jun,Liu, Mingxin,Mi, Zetian,Rashid, Roksana T.,Tan, Lida
, p. 7864 - 7870 (2020/08/19)
Employing photo-energy to drive the desired chemical transformation has been a long pursued subject. The development of homogeneous photoredox catalysts in radical coupling reactions has been truly phenomenal, however, with apparent disadvantages such as the difficulty in separating the catalyst and the frequent requirement of scarce noble metals. We therefore envisioned the use of a hyper-stable III-V photosensitizing semiconductor with a tunable Fermi level and energy band as a readily isolable and recyclable heterogeneous photoredox catalyst for radical coupling reactions. Using the carbonyl coupling reaction as a proof-of-concept, herein, we report a photo-pinacol coupling reaction catalyzed by GaN nanowires under ambient light at room temperature with methanol as a solvent and sacrificial reagent. By simply tuning the dopant, the GaN nanowire shows significantly enhanced electronic properties. The catalyst showed excellent stability, reusability and functional tolerance. All reactions could be accomplished with a single piece of nanowire on Si-wafer. This journal is
Oxidative Cleavage of Alkene C=C Bonds Using a Manganese Catalyzed Oxidation with H2O2 Combined with Periodate Oxidation
Mecozzi, Francesco,Dong, Jia Jia,Angelone, Davide,Browne, Wesley R.,Eisink, Niek N. H. M.
, p. 7151 - 7158 (2019/11/16)
A one-pot multi-step method for the oxidative cleavage of alkenes to aldehydes/ketones under ambient conditions is described as an alternative to ozonolysis. The first step is a highly efficient manganese catalyzed epoxidation/cis-dihydroxylation of alkenes. This step is followed by an Fe(III) assisted ring opening of the epoxide (where necessary) to a 1,2-diol. Carbon–carbon bond cleavage is achieved by treatment of the diol with sodium periodate. The conditions used in each step are not only compatible with the subsequent step(s), but also provide for increased conversion compared to the equivalent reactions carried out on the isolated intermediate compounds. The described procedure allows for carbon–carbon bond cleavage in the presence of other alkenes, oxidation sensitive moieties and other functional groups; the mild conditions (r.t.) used in all three steps make this a viable general alternative to ozonolysis and especially for use under flow or continuous batch conditions.
Silver(I)-Catalyzed Widely Applicable Aerobic 1,2-Diol Oxidative Cleavage
Zhou, Zhong-Zhen,Liu, Mingxin,Lv, Leiyang,Li, Chao-Jun
supporting information, p. 2616 - 2620 (2018/02/13)
The oxidative cleavage of 1,2-diols is a fundamental organic transformation. The stoichiometric oxidants that are still predominantly used for such oxidative cleavage, such as H5IO6, Pb(OAc)4, and KMnO4, generate stoichiometric hazardous waste. Herein, we describe a widely applicable and highly selective silver(I)-catalyzed oxidative cleavage of 1,2-diols that consumes atmospheric oxygen as the sole oxidant, thus serving as a potentially greener alternative to the classical transformations.
Visible light-promoted dihydroxylation of styrenes with water and dioxygen
Yang, Bo,Lu, Zhan
supporting information, p. 12634 - 12637 (2017/12/02)
An efficient visible light promoted metal-free dihydroxylation of styrenes with water and dioxygen has been developed for the construction of vicinal alcohols. The protocol was operationally simple with a broad substrate scope. The mechanistic studies demonstrated that one of the hydroxyl groups came from water and the other one came from molecular oxygen. Additionally, the β-alkyoxy alcohols could also be obtained using a similar strategy.
α,α-Diarylethylene Glycols as Valuable Precursor for Synthesis of 1,1-Diarylethenes and α,α-Diaryl Acetaldehydes
Tiwari, Praveen Kumar,Sivaraman, Balasubramaniam,Aidhen, Indrapal Singh
, p. 3594 - 3605 (2017/07/22)
Towards assembling of diarylmethine unit present in biologically important molecules, we have developed a new Weinreb Amide (WA) based building block derived from glycolic acid. The WA functionality present in this building block permits the sequential addition of various arylmagnesium bromide reagents in a controlled manner that enables assembly of a diarylmethine unit. The developed synthetic route provides easy access to important diarylethenes and α,α-diarylethylene glycols. The synthesized α,α-diarylethylene glycols provide access to synthetically important symmetrical and unsymmetrical α,α-diaryl acetaldehydes as valuable intermediates.
Osmium impregnated on magnetite as a heterogeneous catalyst for the syn-dihydroxylation of alkenes
Cano, Rafael,Pérez, Juana M.,Ramón, Diego J.
, p. 177 - 182 (2014/01/06)
A new catalyst derived from osmium has been prepared, fully characterized and tested in the dihydroxylation of alkenes. The catalyst was prepared by wet impregnation methodology of OsCl3·3H2O on a commercial micro-magnetite surface. The catalyst allowed the reaction with one of the lowest osmium loadings for a heterogeneous catalyst and was selective for the monodihydroxylation of 1,5-dienes. Moreover, the catalyst was easily removed from the reaction medium by the simple use of a magnet. The selectivity of catalyst is very high with conversions up to 99%. Preliminary kinetics studies showed a first-order reaction rate with respect to the catalyst.
Homogeneous and heterogeneous photoredoxcatalyzed hydroxymethylation of ketones and keto esters: Catalyst screening, chemoselectivity and dilution effects
Griesbeck, Axel G.,Reckenthaeler, Melissa
supporting information, p. 1143 - 1150 (2014/06/09)
The homogeneous titanium- and dye-catalyzed as well as the heterogeneous semiconductor particle-catalyzed photohydroxymethylation of ketones by methanol were investigated in order to evaluate the most active photocatalyst system. Dialkoxytitanium dichlorides are the most efficient species for chemoselective hydroxymethylation of acetophenone as well as other aromatic and aliphatic ketones. Pinacol coupling is the dominant process for semiconductor catalysis and ketone reduction dominates the Ti(OiPr)4/methanol or isopropanol systems. Application of dilution effects on the TiO2 catalysis leads to an increase in hydroxymethylation at the expense of the pinacol coupling.
