525-82-6Relevant articles and documents
Chapter Open for the Excited-State Intramolecular Thiol Proton Transfer in the Room-Temperature Solution
Chang, Chao-Che,Chen, Chao-Tsen,Chou, Pi-Tai,Huang, Chun-Hao,Li, Elise Y.,Liao, Yu-Chan,Liu, Yi-Hung,Liu, Zong-Ying,Meng, Fan-Yi,Wang, Chun-Hsiang
, p. 12715 - 12724 (2021/08/30)
We report here, for the first time, the experimental observation on the excited-state intramolecular proton transfer (ESIPT) reaction of the thiol proton in room-temperature solution. This phenomenon is demonstrated by a derivative of 3-thiolflavone (3TF), namely, 2-(4-(diethylamino)phenyl)-3-mercapto-4H-chromen-4-one (3NTF), which possesses an - S - H···O= intramolecular H-bond (denoted by the dashed line) and has an S1 absorption at 383 nm. Upon photoexcitation, 3NTF exhibits a distinctly red emission maximized at 710 nm in cyclohexane with an anomalously large Stokes shift of 12 230 cm-1. Upon methylation on the thiol group, 3MeNTF, lacking the thiol proton, exhibits a normal Stokes-shifted emission at 472 nm. These, in combination with the computational approaches, lead to the conclusion of thiol-type ESIPT unambiguously. Further time-resolved study renders an unresolvable (180 fs) ESIPT rate for 3NTF, followed by a tautomer emission lifetime of 120 ps. In sharp contrast to 3NTF, both 3TF and 3-mercapto-2-(4-(trifluoromethyl)phenyl)-4H-chromen-4-one (3FTF) are non-emissive. Detailed computational approaches indicate that all studied thiols undergo thermally favorable ESIPT. However, once forming the proton-transferred tautomer, the lone-pair electrons on the sulfur atom brings non-negligible nπ? contribution to the S1′ state (prime indicates the proton-transferred tautomer), for which the relaxation is dominated by the non-radiative deactivation. For 3NTF, the extension of π-electron delocalization by the diethylamino electron-donating group endows the S1′ state primarily in the ππ? configuration, exhibiting the prominent tautomer emission. The results open a new chapter in the field of ESIPT, covering the non-canonical sulfur intramolecular H-bond and its associated ESIPT at ambient temperature.
METHOD FOR SYNTHESIZING (Z)-AURONE AND DERIVATIVE COMPOUNDS THEREOF
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Paragraph 0134-0135; 0140, (2021/05/11)
One embodiment of the present invention is described below. Provided is (Z)-operon comprising o - (alkanone -1 - yl) phenol or its derivative compound in a thallium (Tl) catalyst and an cyclization step for cyclizing the compound under an organic solvent, and a method for producing the derivative compound.
Site-Selective Acceptorless Dehydrogenation of Aliphatics Enabled by Organophotoredox/Cobalt Dual Catalysis
Zhou, Min-Jie,Zhang, Lei,Liu, Guixia,Xu, Chen,Huang, Zheng
supporting information, p. 16470 - 16485 (2021/10/20)
The value of catalytic dehydrogenation of aliphatics (CDA) in organic synthesis has remained largely underexplored. Known homogeneous CDA systems often require the use of sacrificial hydrogen acceptors (or oxidants), precious metal catalysts, and harsh reaction conditions, thus limiting most existing methods to dehydrogenation of non- or low-functionalized alkanes. Here we describe a visible-light-driven, dual-catalyst system consisting of inexpensive organophotoredox and base-metal catalysts for room-temperature, acceptorless-CDA (Al-CDA). Initiated by photoexited 2-chloroanthraquinone, the process involves H atom transfer (HAT) of aliphatics to form alkyl radicals, which then react with cobaloxime to produce olefins and H2. This operationally simple method enables direct dehydrogenation of readily available chemical feedstocks to diversely functionalized olefins. For example, we demonstrate, for the first time, the oxidant-free desaturation of thioethers and amides to alkenyl sulfides and enamides, respectively. Moreover, the system's exceptional site selectivity and functional group tolerance are illustrated by late-stage dehydrogenation and synthesis of 14 biologically relevant molecules and pharmaceutical ingredients. Mechanistic studies have revealed a dual HAT process and provided insights into the origin of reactivity and site selectivity.
Iron-Catalyzed ?±,?-Dehydrogenation of Carbonyl Compounds
Zhang, Xiao-Wei,Jiang, Guo-Qing,Lei, Shu-Hui,Shan, Xiang-Huan,Qu, Jian-Ping,Kang, Yan-Biao
supporting information, p. 1611 - 1615 (2021/03/03)
An iron-catalyzed α,β-dehydrogenation of carbonyl compounds was developed. A broad spectrum of carbonyls or analogues, such as aldehyde, ketone, lactone, lactam, amine, and alcohol, could be converted to their α,β-unsaturated counterparts in a simple one-step reaction with high yields.
Continuous flow microchannel synthesis process of flavonoid compounds
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Paragraph 0050-0060, (2021/06/22)
The invention provides a continuous flow microchannel synthesis process of flavonoid compounds. According to the process, hesperidin and iodine elementary substance are used as raw materials and react in a continuous flow microchannel reactor in the presence of a reaction solvent to synthesize the flavonoid compound as shown in a formula A. Compared with a traditional kettle-type preparation process, the process disclosed by the invention has the advantages that the preparation time is obviously shortened, and the conversion rate of raw materials and the yield of products are obviously improved; and especially, when the diosmin is prepared under optimal process conditions of continuous flow microchannel synthesis, the conversion rate of the raw material hesperidin is as high as 96.48%, and the yield of the product diosmin is as high as 81.96%. The continuous flow micro-channel synthesis process provided by the invention is beneficial to realizing safe, efficient and rapid industrial production of flavonoid compounds, and has a wide application prospect.
CF3SOCl-promoted intramolecular cyclization of β-diketones: An efficient synthesis of flavones
Sun, Dong-Wei,Zhou, Yong-Yan,Jiang, Min,Nian, Tang,Liu, Jin-Tao
, (2021/05/31)
An efficient intramolecular cyclization reaction of β-diketones containing a phenyl group with an ortho-hydroxyl substituent was achieved. Using CF3SOCl as an additive, the reaction took place under transition-metal-free and mild conditions. A series of flavones were synthesized in moderate to excellent yields.
A novel one-pot synthesis of flavones
Chang, Meng-Yang,Tsai, Min-Chen,Lin, Chun-Yi
, p. 11655 - 11662 (2021/03/31)
In this paper, a one-pot facile route for the BiCl3/RuCl3-mediated synthesis of functionalized flavones is described, including: (i) intermolecularortho-acylation of substituted phenols with cinnamoyl chlorides, and (ii) intramolecular cyclodehydrogenation of the resultingo-hydroxychalcones. The reaction conditions are discussed herein.
Robust alkyl-bridged bis(N-heterocyclic carbene)palladium(II) complexes anchored on Merrifield's resin as active catalysts for the selective synthesis of flavones and alkynones
Mansour, Waseem,Fettouhi, Mohammed,Saleem, Qasim,El Ali, Bassam
, (2021/02/12)
Highly active and efficient propylene-bridged bis(N-heterocyclic carbene)palladium(II) complexes covalently anchored on Merrifield's resin were synthesized and characterized using various physical and spectroscopic techniques. The two anchored Pd(II) complexes consist of the system: Merrifield's resin-linker-bis(NHC)Pd(II), the linkers being benzyl and benzyl-O-(CH2)3 for (Pd-NHC1@M) and (Pd-NHC2@M), respectively. The short linker anchored bis-benzimidazolium ligand precursor (PBBI-1@M) was synthesized via direct carbon–nitrogen alkylation of a propylene-bridged bis(benzimidazole) (PBBI-1) by Merrifield's resin chlorobenzyl group. The longer linker anchored bis-benzimidazolium ligand precursor (PBBI-2@M) was obtained in a two-step reaction involving first alkylation of (PBBI-1) with 3-chloro-1-propanol followed by a nucleophilic substitution at Merrifield's resin chlorobenzyl group. Both supported ligand precursors (PBBI-1@M and PBBI-2@M) reacted with palladium acetate to produce the two heterogeneous catalysts (Pd-NHC1@M) and (Pd-NHC2@M). 13C NMR palladation shift of the benzimidazole N–C–N (C2) carbon was found very similar in both the liquid NMR spectra of the homogeneous complexes and the CP/MASS spectra of the corresponding covalently anchored complexes. The catalytic activity, stability, and the recycling ability of the supported catalysts have been investigated in the carbonylative Sonogashira coupling reactions of aryl iodides with aryl alkynes and alkyl alkynes and also in the cyclocarbonylative Sonogashira coupling reactions of aryl iodides with aryl alkynes via one pot reactions. The longer linker catalyst Pd-NHC2@M demonstrated excellent catalytic activity, stability, and very high recycling ability in the two carbonylative coupling reactions. These systems exhibit the hypothesized thermodynamic stability offered by the chelate effect in addition to the strong sigma donor ability of a bis(NHC) ligand system generating electron-rich palladium centers that favor the oxidative addition step of the aryl halide.
Divergent synthesis of flavones and flavanones from 2′-hydroxydihydrochalconesviapalladium(ii)-catalyzed oxidative cyclization
Son, Seung Hwan,Cho, Yang Yil,Yoo, Hyung-Seok,Lee, Soo Jin,Kim, Young Min,Jang, Hyu Jeong,Kim, Dong Hwan,Shin, Jeong-Won,Kim, Nam-Jung
, p. 14000 - 14006 (2021/04/22)
Divergent and versatile synthetic routes to flavones and flavanonesviaefficient Pd(ii) catalysis are disclosed. These Pd(ii) catalyses expediently provide a variety of flavones and flavanones from 2′-hydroxydihydrochalcones as common intermediates, depending on oxidants and additives,viadiscriminate oxidative cyclization sequences involving dehydrogenation, respectively, in a highly atom-economic manner.
Comparison of nonheme manganese‐ and iron‐containing flavone synthase mimics
Juraj, Natalija Pantalon,Kaizer, József,Kirin, Sre?ko I.,Lakk‐bogáth, Dóra,Meena, Bashdar I.,Peri?, Berislav
, (2021/06/16)
Heme and nonheme‐type flavone synthase enzymes, FS I and FS II are responsible for the synthesis of flavones, which play an important role in various biological processes, and have a wide range of biomedicinal properties including antitumor, antimalarial, and antioxidant activities. To get more insight into the mechanism of this curious enzyme reaction, nonheme structural and functional models were carried out by the use of mononuclear iron, [FeII(CDA‐BPA*)]2+ (6) [CDA‐BPA = N,N,N’,N’‐tetrakis‐(2‐pyridylmethyl)‐cyclohexanediamine], [FeII(CDA‐BQA*)]2+ (5) [CDA‐BQA = N,N,N’,N’‐tetrakis‐(2‐quinolilmethyl)‐cyclohexanediamine], [FeII(Bn‐TPEN)(CH3CN)]2+ (3) [Bn‐ TPEN = N‐benzyl‐N,N’,N’‐tris(2‐pyridylmethyl)‐1,2‐ diaminoethane], [FeIV(O)(Bn‐TPEN)]2+ (9), and manganese, [MnII(N4Py*)(CH3CN)]2+ (2) [N4Py* = N,N‐bis(2‐pyridylmethyl)‐1,2‐di(2‐pyridyl)ethyl-amine)], [MnII(Bn‐TPEN)(CH3CN)]2+ (4) complexes as catalysts, where the possible reactive inter-mediates, high‐valent FeIV(O) and MnIV(O) are known and well characterised. The results of the catalytic and stoichiometric reactions showed that the ligand framework and the nature of the metal cofactor significantly influenced the reactivity of the catalyst and its intermediate. Comparing the reactions of [FeIV(O)(Bn‐TPEN)]2+ (9) and [MnIV(O)(Bn‐TPEN)]2+ (10) towards flavanone under the same conditions, a 3.5‐fold difference in reaction rate was observed in favor of iron, and this value is three orders of magnitude higher than was observed for the previously published [FeIV(O)(N2Py2Q*)]2+ [N,N‐bis(2‐quinolylmethyl)‐1,2‐di(2‐pyridyl)ethylamine] species.
