20498-68-4Relevant articles and documents
Cobalt Catalyst Determines Regioselectivity in Ring Opening of Epoxides with Aryl Halides
Potrz?saj, Aleksandra,Musiejuk, Mateusz,Cha?adaj, Wojciech,Giedyk, Maciej,Gryko, Dorota
supporting information, p. 9368 - 9376 (2021/06/28)
Ring-opening of epoxides furnishing either linear or branched products belongs to the group of classic transformations in organic synthesis. However, the regioselective cross-electrophile coupling of aryl epoxides with aryl halides still represents a key challenge. Herein, we report that the vitamin B12/Ni dual-catalytic system allows for the selective synthesis of linear products under blue-light irradiation, thus complementing methodologies that give access to branched alcohols. Experimental and theoretical studies corroborate the proposed mechanism involving alkylcobalamin as an intermediate in this reaction.
Enantioselective 1,2-Anionotropic Rearrangement of Acylsilane through a Bisguanidinium Silicate Ion Pair
Cao, Weidi,Tan, Davin,Lee, Richmond,Tan, Choon-Hong
, p. 1952 - 1955 (2018/02/17)
Highly enantioselective bisguanidinium-catalyzed tandem rearrangements of acylsilanes are reported. The acylsilanes were activated via an addition of fluoride on the silicon to form a penta-coordinate anionic silicate intermediate. The silicate then underwent alkyl or aryl group migration from the silicon atom to the neighboring carbonyl carbon atom (1,2-anionotropic rearrangement), followed by [1,2]-Brook rearrangement to provide the secondary alcohols in high yields with excellent enantioselectivities (up to 95% ee). The isolation of an α-silylcarbinol intermediate as well as DFT calculations revealed that the 1,2-anionotropic rearrangement occurred via a bisguanidinium silicate ion pair, which is the stereodetermining step. The chiral center formed is then retained without inversion through the subsequent [1,2]-Brook rearrangement. Crotyl acylsilanes were smoothly transformed into homoallylic linear crotyl alcohols with retention of E/Z geometry, and no branched alcohols were detected. This clearly suggested that the 1,2-anionotropic rearrangement occurred through a three-membered instead of a five-membered transition state.
Ni-catalysed regioselective 1,2-diarylation of unactivated olefins by stabilizing Heck intermediates as pyridylsilyl-coordinated transient metallacycles
Thapa, Surendra,Dhungana, Roshan K.,Magar, Rajani Thapa,Shrestha, Bijay,Kc, Shekhar,Giri, Ramesh
, p. 904 - 909 (2018/02/07)
We report a Ni-catalysed diarylation of unactivated olefins in dimethylpyridylvinylsilane by intercepting Heck C(sp3)-NiX intermediates, derived from aryl halides, with arylzinc reagents. This approach utilizes a modifiable pyridylsilyl moiety as a coordinating group that plays a dual role of intercepting oxidative addition species to promote Heck carbometallation, and stabilizing the Heck C(sp3)-NiX intermediates as transient metallacycles to suppress β-hydride elimination, and facilitate transmetalation/reductive elimination. This method affords 1,2-diarylethylsilanes, which can be readily oxidized to 1,2-diarylethanols that occur as structural motifs in 3-aryl-3,4-dihydroisocoumarin and dihydrostilbenoid natural products.
Synthetic method for diaryl-substituted ethanol compound serving as medical intermediate
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Paragraph 0061; 0062; 0063; 0064; 0065; 0067-0109, (2017/07/21)
The invention relates to a synthetic method for a diaryl-substituted ethanol compound serving as a medical intermediate shown as a formula (III). The method comprises the following steps: reacting a compound shown as a formula (I) and a compound shown as a formula (II) in a hermetic way in an organic solvent in the presence of a catalyst and an alkali; performing posttreatment at the end of the reaction to obtain a compound shown as the formula (III), wherein R1 and R2 are independently selected from H, alkyl with 1-6 carbon atoms, alkoxy with 1-6 carbon atoms or halogen; or R2 and a benzene ring which is connected with the R2 form a naphthalene ring. According to the synthetic method, the diaryl-substituted ethanol compound can be obtained at a high yield through comprehensive selection and coordination of a specific reaction substrate, the catalyst, the alkali and the organic solvent, and has good application prospect and industrial production potential in the field of synthesis of medical intermediates.
Catalytic functionalization of methyl group on silicon: Iridium-catalyzed C(sp3)-H borylation of methylchlorosilanes
Ohmura, Toshimichi,Torigoe, Takeru,Suginome, Michinori
supporting information, p. 17416 - 17419,4 (2012/12/12)
A methyl group of methylchlorosilanes undergoes C-H borylation in an iridium-catalyzed reaction with bis(pinacolato)diboron in cyclohexane at 80 °C, giving (borylmethyl)chlorosilanes selectively.
Preparation and catalytic performances of a molecularly imprinted RU-complex catalyst with an NH2 binding site on a SiO2 surface
Yang, Yong,Weng, Zhihuan,Muratsugu, Satoshi,Ishiguro, Nozomu,Ohkoshi, Shin-Ichi,Tada, Mizuki
experimental part, p. 1142 - 1153 (2012/03/26)
A catalyst surface with an active metal site, a shape-selective reaction space, and an NH2 binding site for o-fluorobenzophenone was designed and prepared by the molecular imprinting of a supported metal complex on a SiO2 surface. A ligand of a SiO2-supported Ru complex that has a similar shape to the product of o-fluorobenzophenone hydrogenation was used as a template. An NH2 binding site for o-fluorobenzophenone was spatially arranged on the wall of a molecularly imprinted cavity with a similar shape to the template. The structures of the SiO2-supported and molecularly imprinted Ru catalysts were characterized in a step-by-step manner by means of solid-state magic angle spinning (MAS) NMR, XPS, UV/Vis, N 2 adsorption, XRF, and Ru K-edge EXAFS. The molecularly imprinted Ru catalyst exhibited excellent shape selectivity for the transfer hydrogenation of benzophenone derivatives. It was found that the NH2 binding site on the wall of the molecularly imprinted cavity enhanced the adsorption of o-fluorobenzophenone, of which the reduction product was imprinted, whereas there was no positive effect in the case of o-methylbenzophenone, which cannot interact with the NH2 binding site through hydrogen bonding. Tailoring a pocket: A molecularly imprinted Ru-complex catalyst with an NH 2 binding site for o-fluorobenzophenone has been successfully designed and prepared on a SiO2 surface for shape-selective transfer hydrogenation (see scheme). Copyright
Nickel-catalyzed cross-coupling of styrenyl epoxides with boronic acids
Nielsen, Daniel K.,Doyle, Abigail G.
supporting information; experimental part, p. 6056 - 6059 (2011/09/13)
Let's get multicatalytic! A Ni0 catalyst complexed with a biaryldialkyl monophosphine ligand facilitates C-C bond formation between styrenyl epoxides and aryl boronic acids (see scheme). X-ray analysis of a catalytically active nickel/ligand complex supports a redox pathway involving C sp 3-O bond activation. A variety of α-substituted alcohols were generated with good reaction efficiency by a multicatalytic sequence. Copyright
Regioselectivity of the rhodium-catalyzed hydroboration of vinyl arenes: Electronic twists and mechanistic shifts
Edwards, David R.,Hleba, Yonek B.,Lata, Christopher J.,Calhoun, Larry A.,Crudden, Cathleen M.
, p. 7799 - 7802 (2008/09/18)
Any substituent does it: The hydroboration of vinyl arenes with pinacol borane (HBPin) and cationic rhodium complexes selectively placed the boron proximal to the aryl rather than phenyl ring, regardless of whether this ring bears electron-donating or electron-withdrawing substituents. In competition experiments between styrene and various vinyl arenes, preferential hydroboration also occured at the substituted arene (see scheme). Hammett plots indicate a break in the mechanism. (Chemical Equation Presented).
Direct preparation of benzylic manganese reagents from benzyl halides, sulfonates, and phosphates and their reactions: Applications in organic synthesis
Suh, YoungSung,Lee, Jun-Sik,Kim, Seoung-Hoi,Rieke, Reuben D.
, p. 20 - 36 (2007/10/03)
The use of highly active manganese (Mn)*, prepared by the Rieke method, was investigated for the direct preparation of benzylic manganese reagents. The oxidative addition of the highly active manganese to benzylic halides was easily completed under mild conditions. Moreover, benzylic manganese sulfonates and phosphates were prepared by direct oxidative addition of Mn* to the carbon-oxygen bonds of benzylic sulfonates and phosphates. The resulting benzylic manganese reagents were found to undergo cross-coupling reactions with a variety of electrophiles. Most of these reactions were carried out in the absence of any transition metal catalyst under mild conditions. In addition, the use of highly active manganese was also studied for preparation of homo-coupled products of functionalized benzyl halides without transition metal catalysts. These useful approaches provided not only a facile synthetic route to the preparation of resoricinolic lipids but a facile synthesis of functionalized 4-benzylpyridines by regioselective and chemo selective γ-addition of benzylic group to N-alkoxycarbonylpyridinum salts.
