271-63-6Relevant articles and documents
Ruthenium-Catalyzed Regioselective C(sp2)-H Activation/Annulation of N-(7-Azaindole)amides with 1,3-Diynes Using N-Amino-7-azaindole as the N, N-Bidentate Directing Group
Pati, Bedadyuti Vedvyas,Sagara, Prateep Singh,Ghosh, Asit,Das Adhikari, Gopal Krushna,Ravikumar, Ponneri Chandrababu
, p. 9428 - 9443 (2021)
The ruthenium(II)-catalyzed regioselective annulation of N-(7-azaindole)amides with 1,3-diynes has been demonstrated. Bioactive N-amino-7-azaindole has been used as a new bidentate directing group to furnish an array of 3-alkynylated isoquinolones. Furthermore, the developed protocol works efficiently for both aryl- and heteroaryl-substituted amides producing a range of pharmacologically useful 7-azaindole-based isoquinolones with a wide range of functionality.
Excited-state double proton transfer of 7-azaindole dimers in a low-temperature organic glass
Lim, Hyeongtaek,Park, Sun-Young,Jang, Du-Jeon
, p. 766 - 771 (2011)
The excited-state double proton transfer of model DNA base pairs, 7-azaindole (7AI) dimers, is explored in a low-temperature organic glass of n-dodecane using picosecond time-resolved fluorescence spectroscopy. Reaction mechanisms are found to depend on the conformations of 7AI dimers at the moment of excitation; whereas planar conformers tautomerize rapidly (10 ps), twisted conformers undergo double proton transfer to form tautomeric dimers on the time scale of 250 ps at 8 K. The proton transfer is found to consist of two orthogonal steps: precursor-configurational optimization and intrinsic proton transfer via tunneling. The rate is almost isotope independent at cryogenic temperatures because configurational optimization is the rate-determining step of the overall proton transfer. This optimization is assisted by lattice vibrations below 150 K or by librational motions above 150 K. The excited-state double proton transfer of model DNA base pairs, 7-azaindole dimers (7AI), is explored in a low-temperature organic glass of n-dodecane using picosecond time-resolved fluorescence spectroscopy. Reaction mechanisms are found to depend on the conformations of 7AI dimers at the moment of excitation; whereas planar conformers tautomerize rapidly, twisted conformers undergo double proton transfer to form tautomeric dimers on the time scale of 250 ps at 8 K. Precursor-configurational optimization is found to determine the overall rate of excited-state double proton transfer at cryogenic temperatures, showing a kinetic isotope effect to be as small as unity.
Photochemistry of Transient Tautomer of 7-Azaindole H-Bonded Dimer Studied by Two-Step Laser Excitation Fluorescence Measurements
Tokumura, Kunihiro,Watanabe, Yukari,Udagawa, Masahiro,Itoh, Michiya
, p. 1346 - 1350 (1987)
Formation of the monomeric tautomer (7H-pyrrolopyridine) in the photodissociation of the transient groun-state dimeric tautomer, generated via excited-state double proton transfer of 7-azaindole H-bonded dimer in 3-methylpentane (MP), was confirmled by transient absorption and two-step laser excitation (TSLE) fluorescence spectroscopies.The intense XeCl laser pulse (308-nm) excitation of the H-bonded dimer in MP at room temperature produced short- (17 μs) and a long-lived (47 μs) transients.The former and latter were ascribed to the dimeric and monomeric tautomers in the ground state, respectively.It is suggested that the second pulse excitation of the short-lived dimeric tautomer induces efficient dissociation to form a monomeric tautomer in the xcited state together with that in the ground state.One-color (308-nm) biphotonic processes within the XeCl laser pulse are therefore responsible for the long-lived monomeric tautomer in the ground state.The decay of the monomeric tautomer in the dark is attributable to the H-transfer reaction to yield 7-azaindole.Significant deuterium isotope effects were found for H-transfer of the monomeric tautomer as well as for photodissociation of the dimeric tautomer.
Anomalously slow proton transport of a water molecule
Park, Sun-Young,Jeong, Hyeok,Jang, Du-Jeon
, p. 6023 - 6031 (2011)
Unusually low proton-transporting ability of a water molecule has been observed in the excited-state proton transfer (ESPT) of a 7-azaindole (7AI) molecule complexed cyclically with a water molecule in diethyl ether and dipropyl ether. In contrast with ultrafast (1 ps) proton diffusion along a systematically structured hydrogen-bond network in an aqueous solution, the proton transport of a water monomer has been observed to be extremely slow (～1 ns) because it is hard for a monomeric water molecule alone to accept or donate a proton. Thus, polar ether molecules surrounding a cyclic hydrogen-bonded 1:1 7AI-water complex (Nc) play a crucial role in the ESPT of Nc. The proton acceptance of a water molecule from the acidic amino group of 7AI via tunneling to form a hydronium ion, which is the rate-determining step, initiates ESPT, and the subsequent rapid proton donation of the hydronium ion to the basic imino group of 7AI takes place barrierlessly to complete ESPT without accumulating any intermediate. Due to the anomalously weak proton-transporting ability of a water monomer, the elaborate reorganization of the hydrogen-bond bridge in Nc to form an optimized precursor configuration is required for proton tunneling.
Solvation of 7-azaindole in alcohols and water: Evidence for concerted, excited-state, double-proton transfer in alcohols
Chen,Gai,Petrich
, p. 10158 - 10166 (1993)
The proton inventory technique is used for the first time to investigate excited-state proton-transfer processes. The nonradiative pathways of the biological probe, 7-azaindole, in methanol, ethanol, and water are examined. Results in methanol and ethanol demonstrate the involvement of two protons in the transition state for the excited-state double-proton transfer process. These data provide the first experimental evidence suggesting a concerted tautomerization reaction of 7-azaindole in alcohols. The data for 7-azaindole in water are interpreted in terms of a nonradiative pathway that is qualitatively different from that in alcohols. We propose abstraction of the N1 hydrogen by water as a possible nonradiative decay process.
Sulfoxylate Anion Radical-Induced Aryl Radical Generation and Intramolecular Arylation for the Synthesis of Biarylsultams
Laha, Joydev K.,Gupta, Pankaj
supporting information, p. 4204 - 4214 (2022/03/16)
Aryl radical generation from the corresponding aryl halides using an electron donor and subsequent intramolecular cyclization with arenes could be an important advancement in contemporary biaryl synthesis. A green and practically useful synthetic protocol to access diverse six- and seven-membered biarylsultams especially with a free NH group including demonstration of a gram-scale synthesis is reported herein. The sulfoxylate anion radical (SO2-?), generated in situ from the reagents rongalite or sodium dithionite (Na2S2O4), was found to be the key single electron transfer agent forming aryl radicals from aryl halides, which upon intramolecular arylation gives biarylsultams with good to excellent yields. The approach features generation of aryl radicals that remained underexplored, use of a cheap and readily available industrial reagents, and transition metal-free, mild, and green reaction conditions.
Development and Scale-Up of an Improved Manufacturing Route to the ATR Inhibitor Ceralasertib
Graham, Mark A.,Askey, Hannah,Campbell, Andrew D.,Chan, Lai,Cooper, Katie G.,Cui, Zhaoshan,Dalgleish, Andrew,Dave, David,Ensor, Gareth,Galan Espinosa, Maria Rita,Hamilton, Peter,Heffernan, Claire,Jackson, Lucinda V.,Jing, Dajiang,Jones, Martin F.,Liu, Pengpeng,Mulholland, Keith R.,Pervez, Mohammed,Popadynec, Michael,Randles, Emma,Tomasi, Simone,Wang, Shenghua
, p. 43 - 56 (2021/01/09)
Ceralasertib is currently being evaluated in multiple phase I/II clinical trials for the treatment of cancer. Its structure, comprising a pyrimidine core decorated with a chiral morpholine, a cyclopropyl sulfoximine and an azaindole, makes it a challenging molecule to synthesize on a large scale. Several features of the medicinal chemistry and early development route make it unsuitable for the long-term commercial manufacture of the active pharmaceutical ingredient. We describe the investigation and development of a new and improved route which introduces the cyclopropyl moiety in a novel process from methyl 2,4-dibromobutyrate. Following construction of the pyrimidine ring, large-scale chlorination with phosphoryl chloride was performed with a safe and robust work-up. An SNAr reaction required an innovative work-up to remove the unwanted regio-isomer, and then a Baeyer-Villiger monooxygenase enzyme was used to enable asymmetric sulfur oxidation to a sulfoxide. A safe and scalable metal-free sulfoximine formation was developed, and then optimization of a Suzuki reaction enabled the manufacture of high-quality ceralasertib with excellent control of impurities and an overall yield of 16%.
Highly Chemoselective Deoxygenation of N-Heterocyclic N-Oxides Using Hantzsch Esters as Mild Reducing Agents
An, Ju Hyeon,Kim, Kyu Dong,Lee, Jun Hee
supporting information, p. 2876 - 2894 (2021/02/01)
Herein, we disclose a highly chemoselective room-temperature deoxygenation method applicable to various functionalized N-heterocyclic N-oxides via visible light-mediated metallaphotoredox catalysis using Hantzsch esters as the sole stoichiometric reductant. Despite the feasibility of catalyst-free conditions, most of these deoxygenations can be completed within a few minutes using only a tiny amount of a catalyst. This technology also allows for multigram-scale reactions even with an extremely low catalyst loading of 0.01 mol %. The scope of this scalable and operationally convenient protocol encompasses a wide range of functional groups, such as amides, carbamates, esters, ketones, nitrile groups, nitro groups, and halogens, which provide access to the corresponding deoxygenated N-heterocycles in good to excellent yields (an average of an 86.8% yield for a total of 45 examples).
Visible-light-mediated organoboron-catalysed metal-free dehydrogenation of N-heterocycles using molecular oxygen
Wei, Lanfeng,Wei, Yu,Xu, Liang,Zhang, Jinli
supporting information, p. 4446 - 4450 (2021/06/30)
The surge of photocatalytic transformation not only provides unprecedented synthetic methods, but also triggers the enthusiasm for more sustainable photocatalysts. On the other hand, oxygen is an ideal oxidant in terms of atom economy and environmental friendliness. However, the poor reactivity of oxygen at the ground state makes its utilization challenging. Herein, a visible-light-induced oxidative dehydrogenative process is disclosed, which uses an organoboron compound as the photocatalyst and molecular oxygen as the sole oxidant.Viathis approach, an array of N-heterocycles have been accessed under metal-free mild conditions, in good to excellent yields.
Transition-Metal-Free and Visible-Light-Mediated Desulfonylation and Dehalogenation Reactions: Hantzsch Ester Anion as Electron and Hydrogen Atom Donor
Heredia, Micaela D.,Guerra, Walter D.,Barolo, Silvia M.,Fornasier, Santiago J.,Rossi, Roberto A.,Budén, Mariá E.
supporting information, p. 13481 - 13494 (2020/12/15)
Novel approaches for N- and O-desulfonylation under room temperature (rt) and transition-metal-free conditions have been developed. The first methodology involves the transformation of a variety of N-sulfonyl heterocycles and phenyl benzenesulfonates to the corresponding desulfonylated products in good to excellent yields using only KOtBu in dimethyl sulfoxide (DMSO) at rt. Alternately, a visible light method has been used for deprotection of N-methyl-N-arylsulfonamides with Hantzsch ester (HE) anion serving as the visible-light-absorbing reagent and electron and hydrogen atom donor to promote the desulfonylation reaction. The HE anion can be easily prepared in situ by reaction of the corresponding HE with KOtBu in DMSO at rt. Both protocols were further explored in terms of synthetic scope as well as mechanistic aspects to rationalize key features of desulfonylation processes. Furthermore, the HE anion induces reductive dehalogenation reaction of aryl halides under visible light irradiation.
