3923-51-1Relevant academic research and scientific papers
Unexpected regioselectivity in the attack of vinyl Grignard reagents to bis(2-benzothiazolyl) ketone
Boga, Carla,Forlani, Luciano,Todesco, Paolo E.
, p. 4845 - 4848 (1997)
The addition of vinyl Grignard reagents to bis(2-benzothiazolyl) ketone affords the unexpected O-alkylation products in very high yields.
Ligand-free (: Z)-selective transfer semihydrogenation of alkynes catalyzed by in situ generated oxidizable copper nanoparticles
Grela, Karol,Kusy, Rafa?
supporting information, p. 5494 - 5502 (2021/08/16)
Herein, we present (Z)-selective transfer semihydrogenation of alkynes based on in situ generated CuNPs in the presence of hydrogen donors, such as ammonia-borane and a green protic solvent. This environmentally friendly method is characterized by operational simplicity combined with high stereo- and chemoselectivity and functional group compatibility. Auto-oxidation of CuNPs after the completion of a semihydrogenation reaction results in the formation of a water-soluble ammonia complex, so that the catalyst may be reused several times by simple phase-separation with no need for any special regeneration processes. Formed NH4B(OR)4 can be easily transformed back into ammonia-borane or into boric acid. In addition, a one-pot tandem sequence involving a Suzuki reaction followed by semihydrogenation was presented, which allows minimization of chemical waste production.
Precursor Nuclearity and Ligand Effects in Atomically-Dispersed Heterogeneous Iron Catalysts for Alkyne Semi-Hydrogenation
Faust Akl, Dario,Ruiz-Ferrando, Andrea,Fako, Edvin,Hauert, Roland,Safonova, Olga,Mitchell, Sharon,López, Núria,Pérez-Ramírez, Javier
, p. 3247 - 3256 (2021/05/31)
Nanostructuring earth-abundant metals as single atoms or clusters of controlled size on suitable carriers opens new routes to develop high-performing heterogeneous catalysts, but resolving speciation trends remains challenging. Here, we investigate the potential of low-nuclearity iron catalysts in the continuous liquid-phase semi-hydrogenation of various alkynes. The activity depends on multiple factors, including the nuclearity and ligand sphere of the metal precursor and their evolution upon interaction with the mesoporous graphitic carbon nitride scaffold. Density functional theory predicts the favorable adsorption of the metal precursors on the scaffold without altering the nuclearity and preserving some ligands. Contrary to previous observations for palladium catalysts, single atoms of iron exhibit higher activity than larger clusters. Atomistic simulations suggest a central role of residual carbonyl species in permitting low-energy paths over these isolated metal centers.
Synthesis of 1-Tri(di)fluoromethyl 1,4-Diketones Enabled by Radical Brook Rearrangement
Chen, Xiang,Liu, Shanshan,Shen, Xiao,Zhang, Jianjun,Zhu, Zhihong
supporting information, p. 4927 - 4931 (2021/09/30)
Herein, we disclose the first and simple one-pot-two-step process to the synthesis of 1-difluoromethyl 1,4-diketones, through Mn-catalyzed radical Brook rearrangement. The methodology is also amenable to the synthesis of 1-trifluoromethyl 1,4-diketones. T
Size- And Shape-Selective Catalysis with a Functionalized Self-Assembled Cage Host
Da Camara, Bryce,Hooley, Richard J.,Ngai, Courtney,Woods, Connor Z.
supporting information, p. 12862 - 12871 (2021/09/28)
A self-assembled Fe4L6 cage with internally oriented carboxylic acid functions was shown to catalyze a variety of dissociative nucleophilic substitution reactions that proceed via oxocarbenium ion or carbocation intermediates. The catalytic behavior of the cage was compared to that of other small acid catalysts, which illustrated large differences in reactivity of the cage-catalyzed reactions, dependent on the structure of the substrate. For example, only a 5% cage confers a 1000-fold rate acceleration of the thioetherification of vinyldiphenylmethanol when compared to the rate with free carboxylic acid surrogates but only a 52-fold acceleration in the formation of small thioacetals. Multiple factors control the variable reactivity in the host, including substrate inhibition, binding affinity, and accessibility of reactive groups once bound. Simple effective concentration increases or the overall charge of the cage does not explain the variations in reactivity shown by highly similar reactants in the host: small differences in structure can have large effects on reactivity. Reaction of large spherical guests is highly dependent on substitution, whereas flat guests are almost unaffected by size and shape differences. The cage is a promiscuous catalyst but has strong selectivity for particular substrate shapes, reminiscent of enzymatic activity.
Evolution of N-Heterocycle-Substituted Iodoarenes (NHIAs) to Efficient Organocatalysts in Iodine(I/III)-Mediated Oxidative Transformations
Boelke, Andreas,Nachtsheim, Boris J.
supporting information, p. 184 - 191 (2019/12/11)
The reactivity of ortho-functionalized N-heterocycle-substituted iodoarenes (NHIAs) as organocatalysts in iodine(I/III)-mediated oxidations was systematically investigated in the α-tosyloxylation of ketones as the model reaction. During a systematic catalyst evolution, it was found that NH-triazoles and benzoxazoles have the most significant positive influence on the reactivity of the central iodine atom. A further catalyst improvement which focused on the substitution pattern of the arene revealed a remarkable ortho-effect. By introduction of an o-OMe group we were able to generate a novel NHIA with a so far unseen catalytic efficiency. This new catalyst is not only easy to synthesize but also enabled the α-tosyloxylation of carbonyl compounds at the lowest reported catalyst loading of only 1 mol%. Finally, the performance of this iodine(I) catalyst was successfully demonstrated in intramolecular oxidative couplings of biphenyls and oxidative rearrangements. (Figure presented.).
Photo-induced phosphorus radical involved semipinacol rearrangement reaction: Highly synthesis of γ-oxo-phosphonates
Wang, Chunhai,Huang, Xiaoling,Liu, Xueting,Gao, Suqian,Zhao, Bin,Yang, Shangdong
supporting information, p. 677 - 680 (2019/08/27)
Hydroxyphosphoric acids display the unique biological activities, and they have some attractive prospects as clinical drug moleculars. Herein, a new approach for the synthesis of γ-oxo-phosphonates (the precursor of hydroxyphosphoric acid) has been established through the semipinacol rearrangement tactic involved the photo-induced phosphorus radical process. Most important, this transformation is avoid of the external oxidants, and occurs very well under the sunlight irradiation, meanwhile the γ-oxo-phosphonate was easily derivatized to obtain γ-hydroxyphosphoric acid, thus highlights the synthesis value of this method.
Photo/N-Heterocyclic Carbene Co-catalyzed Ring Opening and γ-Alkylation of Cyclopropane Enal
Dai, Lei,Ye, Song
supporting information, p. 986 - 990 (2020/02/28)
An unprecedented photo/NHC-co-catalyzed ring-opening C-C bond cleavage of cyclopropane enal and the following γ-alkylation with a halogenated compound via radicals were established, affording the corresponding γ-alkylated α,β-unsaturated esters in moderate to good yields.
I2/Li2CO3-promoted cyanation of diarylalcohols through a dual activation process
Hu, Liangzhen,Hussain, Muhammad Ijaz,Deng, Qingfu,Liu, Qing,Feng, Yangyang,Zhang, Xiaohui,Xiong, Yan
, p. 308 - 314 (2018/12/11)
One-step base promoted strategy for cyanation of α,α-diaryl alcohols has been developed under mild and transition metal-free conditions. This method provides a straightforward and facile way towards the synthesis of β,γ-unsaturated nitriles and α-phenylnitiriles from α-vinyl carbinols and α,α-diaryl methanols, respectively, up to 99% yield. Moreover, various azides and ethers could also be accessed from their respective nucleophiles under standard reaction conditions.
Organoiodine-Catalyzed Enantioselective Alkoxylation/Oxidative Rearrangement of Allylic Alcohols
Zhang, Dong-Yang,Zhang, Ying,Wu, Hua,Gong, Liu-Zhu
supporting information, p. 7450 - 7453 (2019/05/10)
An enantioselective catalytic alkoxylation/oxidative rearrangement of allylic alcohols has been established by using a Br?nsted acid and chiral organoiodine. The presence of 20 mol % of an (S)-proline-derived C2-symmetric chiral iodine led to enantioenriched α-arylated β-alkoxylated ketones in good yields and with high levels of enantioselectivity (84–94 % ee).
