22985-90-6Relevant academic research and scientific papers
Effects of Lewis acids and bases on the carbotitanation of unsaturated hydrocarbons and ketones with η3-allyl(di-η5-cyclopentadienyl)titanium(III)
Eisch, John J.,Boleslawski, Marek P.
, p. C1 - C4 (1987)
The carbotitanating action of η3-allyl(di-η5-cyclopentadienyl)titanium(III) toward ethylene and other unsaturated hydrocarbons, such as trimethyl(phenylethynyl)silane, and toward ketones has been shown to be promoted by Lewis acids s
Geometry determination of tetrasubstituted stilbenes by proton NMR spectroscopy
Fluxá, Viviana S.,Jenny, Titus A.,Bochet, Christian G.
, p. 3793 - 3795 (2005)
A simple spectroscopic method was applied to determine the geometry of tetrasubstituted alkenes. The observation of the 5J-coupling constants in proton NMR spectra on the 13C satellite signals could confirm the previous misassignment of 2,3-diphenylbutene. Hence, the (E)-isomer showed a 1.5 Hz coupling constant, whereas the (Z)-isomer showed a 1.1 Hz coupling constant. Based on this new assignment and a stereospecific preparation, we also propose a revision concerning the NMR data of 2,3-diphenyl-2,3-butanediol.
CBZ6 as a Recyclable Organic Photoreductant for Pinacol Coupling
Wang, Hua,Qu, Jian-Ping,Kang, Yan-Biao
supporting information, p. 2900 - 2903 (2021/05/05)
A recyclable organic photoreductant (1 mol % CBZ6)-catalyzed reductive (pinacol) coupling of aldehydes, ketones, and imines has been developed. Irradiated by purple light (407 nm) using triethylamine as an electron donor, a variety of 1,2-diols and 1,2-diamines could be prepared. The oxidation potential of the excited state of CBZ6 is established as -1.92 V (vs saturated calomel electrode (SCE)). The relative high reductive potential enables the reductive coupling of carbonyl compounds and their derivatives. CBZ6 can be prepared in gram scale and is acid/base- or air-stable. It could be applied in large-scale photoreductive synthesis and recovered in high yield after the reaction.
Facile pinacol coupling of aliphatic ketones by Brook rearrangement in the presence of samarium species
Wang, Xincan,Xie, Guanqun,Zhao, Yanfei,Zheng, Ke,Fang, Yanxiong,Wang, Xiaoxia
supporting information, (2021/04/27)
Herein we report a practical pinacol coupling reaction, in which ketones (aldehydes) react smoothly with Sm and TMSBr to afford the diol products with Sm(II) or (III) siliyl species generated in situ. This reported method affords poor yields for aromatic ketone substrates and good yields for aliphatic ketones. Therefore, it distinguishes from most reductive coupling approaches that are more effective for aromatic carbonyl compounds and provides a facile and robust approach for the pinacol coupling of aliphatic ketones. Mechanistic studies also indicated the pinacolization probably proceeded via an anionic instead of radical coupling pathway involving the Brook rearrangement in the presence of samarium (II or III) silyl species.
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
Light-enabled metal-free pinacol coupling by hydrazine
Qiu, Zihang,Pham, Hanh D. M.,Li, Jianbin,Li, Chen-Chen,Castillo-Pazos, Durbis J.,Khaliullin, Rustam Z.,Li, Chao-Jun
, p. 10937 - 10943 (2019/12/23)
Efficient carbon-carbon bond formation is of great importance in modern organic synthetic chemistry. The pinacol coupling discovered over a century ago is still one of the most efficient coupling reactions to build the C-C bond in one step. However, traditional pinacol coupling often requires over-stoichiometric amounts of active metals as reductants, causing long-lasting metal waste issues and sustainability concerns. A great scientific challenge is to design a metal-free approach to the pinacol coupling reaction. Herein, we describe a light-driven pinacol coupling protocol without use of any metals, but with N2H4, used as a clean non-metallic hydrogen-atom-transfer (HAT) reductant. In this transformation, only traceless non-toxic N2 and H2 gases were produced as by-products with a relatively broad aromatic ketone scope and good functional group tolerance. A combined experimental and computational investigation of the mechanism suggests that this novel pinacol coupling reaction proceeds via a HAT process between photo-excited ketone and N2H4, instead of the common single-electron-transfer (SET) process for metal reductants.
Implementing Hydrogen Atom Transfer (HAT) Catalysis for Rapid and Selective Reductive Photoredox Transformations in Continuous Flow
Steiner, Alexander,Williams, Jason D.,Rincón, Juan A,de Frutos, Oscar,Mateos, Carlos,Kappe, C. Oliver
supporting information, p. 5807 - 5811 (2019/08/01)
The reductive transformation of aryl halides and carbonyl compounds is a key step in many photoredox transformations. By combining a highly reducing organic photocatalyst with a thiol hydrogen atom transfer (HAT) catalyst, we showcase rapid and highly selective reactions of these synthetically important starting materials in continuous flow. The fast reduction of aryl iodides, bromides and chlorides has been demonstrated with residence times in some cases below one minute. Selectivity between mono- and di-dehalogenation could also be achieved in some cases. Aryl ketones, aldehydes and imines were shown to undergo facile pinacol couplings, and the coupling of an aryl chloride with a styrene was also successful.
Zinc-Mediated Efficient and Selective Reduction of Carbonyl Compounds
Mandal, Tirtha,Jana, Snehasish,Dash, Jyotirmayee
, p. 4972 - 4983 (2017/09/13)
We herein describe for the first time that an optimized combination of Zn and NH4Cl can be used for the selective reduction of aldehydes and ketones to the corresponding alcohols. The aldehyde and keto groups are selectively reduced in the presence of azide, cyano, epoxy, ester, and carbon–carbon double-bond functional groups. A broad functional-group compatibility, chemoselective reduction of aldehydes in the presence of ketones, and selective reduction of isatins at the C3 carbonyl group are the highlights of the present method.
MeOH or H2O as efficient additive to switch the reactivity of allylSmBr towards carbonyl compounds
Li, Jianyong,Niu, Qingsheng,Li, Shanchan,Sun, Yuehao,Zhou, Qian,Lv, Xin,Wang, Xiaoxia
supporting information, p. 1250 - 1253 (2017/03/10)
A variety of carbonyl compounds were treated by allylSmBr (allylSmBr) with MeOH as the cosolvent to have further insights on the previously reported reductive coupling of aryl ketones mediated by Sm/alkyl halide/MeOH. The results demonstrate that the real reducing species in Sm/alkyl halide/MeOH system should be allylSmBr, and MeOH has elegantly switched the reactivity of allylSmBr from being nucleophilic to being good reductive coupling reagent. Besides, H2O was also found to be a useful additive to realize the pinacol coupling of aliphatic aldehydes and ketones promoted by allylSmBr.
Metal-free reductive coupling of CO and CN bonds driven by visible light: Use of perylene as a simple photoredox catalyst
Okamoto, Shusuke,Kojiyama, Keita,Tsujioka, Hiroki,Sudo, Atsushi
supporting information, p. 11339 - 11342 (2016/09/23)
Perylene, a simple polycyclic aromatic hydrocarbon, was used as a photoredox catalyst to enable the reductive coupling reaction of aromatic aldehydes, ketones, and an imine under visible-light irradiation using a white LED.
