930-36-9Relevant articles and documents
Protodeboronation of (Hetero)Arylboronic Esters: Direct versus Prehydrolytic Pathways and Self-/Auto-Catalysis
Assante, Michele,Geogheghan, Katherine J.,Hayes, Hannah L. D.,Jin, Na,Leach, Andrew G.,Lloyd-Jones, Guy C.,Noonan, Gary,Tomasi, Simone,Wei, Ran
supporting information, p. 14814 - 14826 (2021/09/13)
The kinetics and mechanism of the base-catalyzed hydrolysis (ArB(OR)2→ ArB(OH)2) and protodeboronation (ArB(OR)2→ ArH) of a series of boronic esters, encompassing eight different polyols and 10 polyfluoroaryl and heteroaryl moieties, have been investigated by in situ and stopped-flow NMR spectroscopy (19F,1H, and11B), pH-rate dependence, isotope entrainment,2H KIEs, and KS-DFT computations. The study reveals the phenomenological stability of boronic esters under basic aqueous-organic conditions to be highly nuanced. In contrast to common assumption, esterification does not necessarily impart greater stability compared to the corresponding boronic acid. Moreover, hydrolysis of the ester to the boronic acid can be a dominant component of the overall protodeboronation process, augmented by self-, auto-, and oxidative (phenolic) catalysis when the pH is close to the pKaof the boronic acid/ester.
Cooperative Au/Ag Dual-Catalyzed Cross-Dehydrogenative Biaryl Coupling: Reaction Development and Mechanistic Insight
Li, Weipeng,Yuan, Dandan,Wang, Guoqiang,Zhao, Yue,Xie, Jin,Li, Shuhua,Zhu, Chengjian
supporting information, p. 3187 - 3197 (2019/02/19)
An operationally simple and highly selective Au/Ag bimetallic-catalyzed cross-dehydrogenative biaryl coupling between pyrazoles and fluoroarenes has been developed. With this reaction, a wide range of biheteroaryl products can be obtained in moderate to good yields with excellent functional group compatibility. The exact role of silver salts, previously overlooked in most gold-catalyzed transformations, has been carefully investigated in this biaryl coupling. Insightful experimental and theoretical studies indicate that silver acetate is the actual catalyst for C-H activation of electron-poor arenes, rather than the previously reported gold(I)-catalyzed process. An unprecedented Au/Ag dual catalysis is proposed, in which silver(I) is responsible for the activation of electron-poor fluoroarenes via a concerted metalation-deprotonation pathway, and gold(III) is responsible for the activation of electron-rich pyrazoles via an electrophilic aromatic substitution process. Kinetic studies reveal that ArFnAu(III)-mediated C-H activation of pyrazoles is most likely the rate-limiting step.
Alkylation method for nitrogen-hydrogen containing compounds and application thereof
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Paragraph 0059; 0060, (2018/10/04)
The invention discloses an alkylation method for nitrogen-hydrogen containing compounds and an application thereof, belonging to the technical field of synthesis of organic compounds. The invention provides a series of methods for a nitrogen alkylation reaction of N-H containing heterocyclic compounds (II) with N,N-dimethylformamide dialkyl acetal as an alkyl source under the condition of no participation of metals, and a product with a hydrogen atom on a nitrogen atom substituted by R1 is obtained. The method provided by the invention has the advantages of highly-efficient reaction, high yield, simple treatment after the reaction, simple and convenient operation, mild reaction conditions, no participation of the metals, high tolerance of functional groups of a reaction substrate, wide range and easy preparation of the substrate, high reaction efficiency after amplification of the reaction, and applicability to large-scale industrial production.
A practical and highly efficient reductive dehalogenation of aryl halides using heterogeneous Pd/AlO(OH) nanoparticles and sodium borohydride
Kara, Belguzar Yasemin,Yazici, Melike,Kilbas, Benan,Goksu, Haydar
, p. 5898 - 5902 (2016/09/07)
The reductive dehalogenation of aryl halides was performed by using commercially available aluminium oxy-hydroxide-supported palladium (Pd/AlO(OH)) nanoparticles of about 3?nm size (0.5?wt.?% Pd) with sodium borohydride. The dehalogenated products were obtained with absolute conversion in a mixture of H2O/MeOH (v/v=1/1) under ultrasonic conditions at room temperature. All aryl halides were successfully converted to halogen-free compounds within 1.5–4?h with yields of over 95%. The one-pot catalytic method is presented as a new process for the reductive dehalogenation of halogenated compounds. This method is quite simple, highly efficient and eco-friendly, and has an exceptional recovery rate.
Synthesis of biologically active seven-membered-ring heterocycles
Reekie, Tristan A.,Kavanagh, Madeline E.,Longworth, Mitchell,Kassiou, Michael
, p. 3211 - 3227 (2013/12/04)
Seven-membered rings that contain one or more heteroatoms are interesting motifs for organic synthesis. In addition to their synthetic interest, they play an important role in industrial and pharmaceutical chemistry with generally increased central nervous system activity when flanked by aromatic rings. Herein we report a brief summary of some key methods of preparation for seven-membered-ring heterocycles and how they have been applied to the synthesis of commercially desirable products. We then detail new methods that we have developed for the synthesis of biologically active compounds containing this motif. Georg Thieme Verlag Stuttgart New York.
Pyrazolium- versus imidazolium-based ionic liquids: Structure, dynamics and physicochemical properties
Chiappe, Cinzia,Sanzone, Angelo,Mendola, Daniele,Castiglione, Franca,Famulari, Antonino,Raos, Guido,Mele, Andrea
, p. 668 - 676 (2013/03/14)
Ionic liquids (ILs) composed of two different pyrazolium cations with dicyanamide and bis(trifluoromethanesulfonyl)imide anions have been synthesized and characterized by NMR, Kamlet-Taft solvatochromic parameters, conductivity and rheological measurements, as well as ab initio calculations. Density functional calculations for the two pyrazolium cations, 1-butyl-2- methylpyrazolium [bmpz] and 1-butyl-2,3,5-trimethylpyrazolium [bm 3pz], provide a full picture of their conformational states. Homo- and heteronuclear NOE show aggregation motives sensitive to steric hindrance and the anions' nature. Self-diffusion coefficients D for the anion and the cation have been measured by pulsed field gradient spin-echo NMR (PGSE-NMR). The ionic diffusivity is influenced by their chemical structure and steric hindrance, giving the order Dcation > Danion for all of the examined compounds. The measured ion diffusion coefficients, viscosities, and ionic conductivity follow the Vogel-Fulcher-Tammann (VFT) equation for the temperature dependencies, and the best-fit parameters have been determined. Solvatochromic parameters indicate an increased ion association upon going from bis(trifluoromethanesulfonyl)imide to dicyanamide-based pyrazolium salts, as well as specific hydrogen bond donor capability of H atoms on the pyrazolium ring. All of these physical properties are compared to those of an analogous series of imidazolium-based ILs.
Process development and large-scale synthesis of a c-Met kinase inhibitor
Stewart, Gavin W.,Brands, Karel M. J.,Brewer, Sarah E.,Cowden, Cameron J.,Davies, Antony J.,Edwards, John S.,Gibson, Andrew W.,Hamilton, Simon E.,Katz, Jason D.,Keen, Stephen P.,Mullens, Peter R.,Scott, Jeremy P.,Wallace, Debra J.,Wise, Christopher S.
scheme or table, p. 849 - 858 (2011/03/20)
A highly convergent synthesis of c-Met kinase inhibitor 1 has been demonstrated on a multikilogram scale using three key fragments: dihalotricyclic core 2, chiral sulfamide side chain 3, and pyrazole boronic ester 4. The chirality in sulfamide side chain 3 was installed using the cheap and readily available starting material (S)-epichlorohydrin. A total of 2.71 kg of 1 were isolated in seven steps (the longest linear sequence).
PROCESSES FOR PRODUCING N-ALKYLPYRAZOLE
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Page/Page column 4-5, (2009/12/05)
Processes are provided for combining nonsubstituted hydrazine (N2H4), a strong acid, alcohol, and tetraalkoxypropane to produce N-alkylpyrazole.
An improved synthesis of 1-methyl-1H-pyrazole-4-boronic acid pinacol ester and its corresponding lithium hydroxy ate complex: application in Suzuki couplings
Mullens, Peter R.
experimental part, p. 6783 - 6786 (2010/04/27)
An improved synthesis of 1-methyl-1H-pyrazole-4-boronic acid pinacol ester via isolation of the corresponding lithium hydroxy ate complex is described. The hydroxy ate complex is available in one pot from 4-bromo-1-methyl-1H-pyrazole and triisopropyl borate, and is isolated by filtration in high yield. Furthermore, the resulting lithium hydroxy ate complex has long-term bench stability and can be employed directly in Suzuki couplings without the need for added base.
Two-stage sonogashira coupling method in the synthesis of auxin active acetylenes
Wayne Craig,Eberle, Martin,Irminger, Bruno,Schueckenboehmer, Anegret,Laime, Yvette,Mueller, Patrick
, p. 1967 - 1974 (2008/09/16)
A sequential Sonogashira coupling of a protected acetylene precursor with aryl halides (5) followed by pyrazolyl iodides (14) allows efficient access to the unsymmetrical aryl-heteroarylacetylene (8). Subsequent regioselective lithiation exchange followed by dimethyl oxalate quench produced readily vicinal ketoesters (9) which show auxin effects in a wide variety of plant species.
