- AMIDE AND THIOAMIDE BANDS OF BENZANILIDE AND THIOBENZANILIDE IN THE VIBRATIONAL SPECTRA
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It has been widely accepted that in secondary amides and secondary thioamides, in the spectral region between 1600 and 1200 cm-1 two characteristic bands could be recognized (Amide II and Amide III for amides and B and C bands for thioamides).Our spectra of benzanilide, C6H5(C=O)NHC6H5, and thiobenzanilide, C6H5(C=S)NHC6H5, show that in this region there are, at least, four prominent bands which shift on deuteration.That could indicate that all these bands are in connection with the vibrations of amide and/or thioamide groups.Some other amide and thioamide bands have been also discussed.
- Petrov, I.,Grupce, O.
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- Chemoselective Transamidation of Thioamides by Transition-Metal-Free N?C(S) Transacylation
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Thioamides represent highly valuable isosteric in the strictest sense “single-atom substitution” analogues of amides that have found broad applications in chemistry and biology. A long-standing challenge is the direct transamidation of thioamides, a process which would convert one thioamide bond (R?C(S)?NR1R2) into another (R?C(S)?NR3N4). Herein, we report the first general method for the direct transamidation of thioamides by highly chemoselective N?C(S) transacylation. The method relies on site-selective N-tert-butoxycarbonyl activation of 2° and 1° thioamides, resulting in ground-state-destabilization of thioamides, thus enabling to rationally manipulate nucleophilic addition to the thioamide bond. This method showcases a remarkably broad scope including late-stage functionalization (>100 examples). We further present extensive DFT studies that provide insight into the chemoselectivity and provide guidelines for the development of transamidation methods of the thioamide bond.
- Hong, Xin,Li, Guangchen,Szostak, Michal,Xing, Yangyang,Zhang, Jin,Zhao, Hui
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- The structures of ring-expanded NHC supported copper(
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Three ring-expanded N-heterocyclic carbene-supported copper(i) triphenylstannyls have been synthesised by the reaction of (RE-NHC)CuOtBu with triphenylstannane (RE-NHC = 6-Mes, 6-Dipp, 7-Dipp). The compounds were characterised by NMR spectroscopy and X-ray crystallography. Reaction of (6-Mes)CuSnPh3 with di-p-tolyl carbodiimide, phenyl isocyanate and phenylisothiocyanate gives access to a copper(i) benzamidinate, benzamide and benzothiamide respectively via phenyl transfer from the triphenylstannyl anion with concomitant formation of (Ph2Sn)n. Attempts to exploit this reactivity under a catalytic regime were hindered by rapid copper(i)-catalysed dismutation of Ph3SnH to Ph4Sn, various perphenylated tin oligomers, H2 and a metallic material thought to be Sn(0). Mechanistic insight was provided by reaction monitoring via NMR spectroscopy and mass spectrometry.
- Charman, Rex S. C.,Liptrot, David J.,Lowe, John P.,Mahon, Mary F.
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supporting information
p. 831 - 835
(2022/02/01)
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- An efficient and straightforward approach for accessing thionoesters: Via palladium-catalyzed C-N cleavage of thioamides
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We report for the first time the coupling of activated thioamides with alcohols to efficiently form thionoesters via a palladium-catalyzed C-N cleavage strategy. The new approach employs thioamides as a thioacylating reagent to give thionoesters in moderate to good yields. Notably, this methodology demonstrates a broad substrate scope, as alkyl/aryl alcohols are well tolerated, and this process might facilitate the synthesis of sulfur-containing compounds under simple and mild conditions. This journal is
- Liu, Yinbo,Mo, Xiaofeng,Majeed, Irfan,Zhang, Mei,Wang, Hui,Zeng, Zhuo
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supporting information
p. 1532 - 1537
(2022/03/01)
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- Dehydrative Beckmann rearrangement and the following cascade reactions
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The Beckmann rearrangement has been predominantly studied for the synthesis of amide and lactam. By strategically using the in situ generated Appel's salt or Mitsunobu's zwitterionic adduct as the dehydrating agent, a series of Beckmann rearrangement and following cascade reactions have been developed herein. The protocol allows the conversion of various ketoximes into amide, thioamide, tetrazole and imide products in modular procedures. The generality and tolerance of functionalities of this method have been demonstrated.
- Liu, Yinghui,Wei, Yongjiao,Xie, Lan-Gui
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supporting information
(2021/11/16)
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- A chromatography-free and aqueous waste-free process for thioamide preparation with Lawesson's reagent
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After completing the thio-substitution with Lawesson's reagent, ethanol was found to be effective in the decomposition of the inherent stoichiometric six-membered-ring byproduct from the Lawesson's reagent to a highly polarized diethyl thiophosphonate. The treatment significantly simplified the following chromatography purification of the desired thioamide in a small scale preparation. As scaling up the preparation of two pincer-type thioamides, we have successfully developed a convenient process with ethylene glycol to replace ethanol during the workup, including a traditional phase separation, extraction, and recrystallization. The newly developed chromatography-free procedure did not generate P-containing aqueous waste, and only organic effluents were discharged. It is believed that the optimized procedure offers the great opportunity of applying the Lawesson's reagent for various thio-substitution reactions on a large scale.
- Wu, Ke,Ling, Yichen,Ding, An,Jin, Liqun,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu,Hu, Xinquan
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p. 805 - 812
(2021/05/03)
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- Visible-Light Carbon Nitride-Catalyzed Aerobic Cyclization of Thiobenzanilides under Ambient Air Conditions
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A metal-free heterogeneous photocatalysis has been developed for the synthesis of benzothiazoles via intramolecular C-H functionalization/C-S bond formation of thiobenzanilides by inexpensive graphitic carbon nitride (g-C3N4) under visible-light irradiation. This reaction provides access to a broad range of 2-substituted benzothiazoles in high yields under an air atmosphere at room temperature without addition of a strong base or organic oxidizing reagents. In addition, the catalyst was found to be stable and reusable after five reaction cycles.
- Bai, Jin,Yan, Sijia,Zhang, Zhuxia,Guo, Zhen,Zhou, Cong-Ying
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supporting information
p. 4843 - 4848
(2021/06/28)
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- Transition-Metal-Free, General Construction of Thioamides from Chlorohydrocarbon, Amide and Elemental Sulfur
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A general method for one-pot synthesis of thioamides is developed through a three-component reaction involving chlorohydrocarbon, amide and elemental sulfur. Such a strategy does not only avoid residual transition metal in the product but also prevent the generation of C?N coupling by-product. The latter is prone to be generated when alkane halide and amine are present. With the protocol proposed in this work, both alkyl and aryl thioamides can be obtained in moderate to excellent yields with a high tolerance of various functional groups. External oxidants are not required in the reaction. In addition, the reaction mechanisms are addressed using a combination of controlling experiments and quantum chemical calculations.
- Chen, Xinzhi,Ge, Xin,Jin, Hao,Qian, Chao,Zhou, Shaodong
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supporting information
p. 3403 - 3406
(2021/06/25)
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- Benzothiazole solid-state luminescent material as well as preparation method and application thereof
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The invention provides a benzothiazole solid-state luminescent material as well as a preparation method and an application thereof, and relates to the technical field of solid-state luminescent materials. The benzothiazole solid-state luminescent material provided by the invention has a structure shown as a formula I, wherein Ar in the formula I is phenyl, naphthyl or anthryl. The benzothiazole solid-state luminescent material provided by the invention is good in color tone, saturation and color rendering property, high in luminous efficiency, and strong in light stability and chemical stability. As shown in the result of the embodiment of the invention, the chromaticity coordinate of the benzothiazole solid-state luminescent material provided by the invention is (0.27-0.28, 0.34-0.38), the color rendering index is 64-73, the color temperature is 8089-8341, and the lighting effect is 4.8-5.68 lm/W.
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Paragraph 0091; 0095-0096
(2020/10/05)
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- Exogenous Photosensitizer-, Metal-, and Base-Free Visible-Light-Promoted C-H Thiolation via Reverse Hydrogen Atom Transfer
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Visible-light-driven, intramolecular C(sp2)-H thiolation has been achieved without addition of a photosensitizer, metal catalyst, or base. This reaction induces the cyclization of thiobenzanilides to benzothiazoles. The substrate absorbs visible light, and its excited state undergoes a reverse hydrogen-atom transfer (RHAT) with 2,2,6,6-tetramethylpiperidine N-oxyl to form a sulfur radical. The addition of the sulfur radical to the benzene ring gives an aryl radical, which then rearomatizes to benzothiazole via RHAT.
- Xu, Ze-Ming,Li, Hong-Xi,Young, David James,Zhu, Da-Liang,Li, Hai-Yan,Lang, Jian-Ping
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supporting information
p. 237 - 241
(2019/01/10)
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- Photocatalytic Oxidative C-H Thiolation: Synthesis of Benzothiazoles and Sulfenylated Indoles
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We report studies on the photocatalytic formation of C-S bonds to form benzothiazoles via an intramolecular cyclization and sulfenylated indoles via an intermolecular reaction. Cyclic voltammetry (CV) and density functional theory studies suggest that benzothiazole formation proceeds via a mechanism that involves an electrophilic sulfur radical, while the indole sulfenylation likely proceeds via a nucleophilic sulfur radical adding into a radical cationic indole. These conditions were successfully extended to several thiobenzamides and indole substrates.
- Aceves, Ernesto Millan,Albright, Samuel T.,Cedano, Mario R.,Dinh, Andrew N.,Gustafson, Jeffrey L.,Nguyen, Ashley D.,Smith, Diane K.
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supporting information
p. 1648 - 1655
(2019/08/26)
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- Sulfur-Catalyzed Oxidative Coupling of Dibenzyl Disulfides with Amines: Access to Thioamides and Aza Heterocycles
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In the presence of catalytic amounts of elemental sulfur, dibenzyl disulfide/DMSO was found to be an excellent thiobenzoylating agent of amines to provide a wide range of thioamides. The reaction becomes autocatalytic when anilines substituted by an o-cyclizable group were used as nucleophile, leading to the corresponding 2-aryl aza heterocycles. (Figure presented.).
- Nguyen, Thanh Binh,Nguyen, Le Phuong Anh,Nguyen, Thi Thu Tram
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supporting information
p. 1787 - 1791
(2019/02/26)
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- Transition metal-free α-Csp3-H oxidative sulfuration of benzyl thiosulfates with anilines to form N-aryl thioamides
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A metal-free approach to N-aryl thioamides from Bunte salts and anilines in DMSO has been developed. This method tolerated a wide range of functional groups on the aromatic ring, providing an ideal way to N-aryl thioamides in good to excellent yields from cheap and easily available starting materials. A plausible mechanism was also proposed based on the X-ray single crystal diffraction, NMR and MS analyses of DMSO-concerning intermediates.
- Qiao, Mengjun,Zhang, Jinli,Chen, Ling,Zhou, Fengyi,Zhang, Yali,Zhou, Lingfei,Wu, Yangjie
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supporting information
p. 3790 - 3796
(2019/04/17)
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- Functionalization of activated methylene C-H bonds with nitroarenes and sulfur for the synthesis of thioamides
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We report a method to obtain arylthioamides by the functionalization of sp3 C-H bonds in phenylacetic acids and benzyl alcohols. Reactions proceeded without the use of any solvents and were compatible with many functionalities and heterocycles. These conditions allow for a rapid synthesis of thioamides from simple, commercial substrates.
- Do, Nhan T.,Tran, Khoa M.,Phan, Hao T.,To, Tuong A.,Nguyen, Tung T.,Phan, Nam T. S.
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supporting information
p. 8987 - 8991
(2019/10/28)
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- Catalyst- and Supporting-Electrolyte-Free Electrosynthesis of Benzothiazoles and Thiazolopyridines in Continuous Flow
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A catalyst- and supporting electrolyte-free method for electrochemical dehydrogenative C?S bond formation in continuous flow has been developed. A broad range of N-arylthioamides have been converted to the corresponding benzothiazoles in good to excellent yields and with high current efficiencies. This transformation is achieved using only electricity and laboratory grade solvent, avoiding degassing or the use of inert atmosphere. This work highlights three advantages of electrochemistry in flow, which is (i) a supporting electrolyte-free reaction, (ii) an easy scale-up of the reaction without the need for a larger reactor and, (iii) the important and effective impact of having a good mixing of the reaction mixture, which can be achieved effectively with the use of flow systems. This clearly improves the reported methods for the synthesis of benzothiazoles.
- Folgueiras-Amador, Ana A.,Qian, Xiang-Yang,Xu, Hai-Chao,Wirth, Thomas
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supporting information
p. 487 - 491
(2017/12/15)
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- Iodoalkyne-Based Catalyst-Mediated Activation of Thioamides through Halogen Bonding
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Halogen bonding catalysis has recently gained increasing attention as a powerful tool to activate organic molecules. However, the variety of the catalyst structure has been quite limited so far. Herein, we report the first example of the use of an iodoalkyne as a halogen bond donor catalyst. By using an iodoalkyne bearing a pentafluorophenyl group as a catalyst, thioamides were efficiently activated and reacted with 2-aminophenol to generate benzoxazoles in good yield. Mechanistic studies, including 13C NMR spectroscopic analysis and several control experiments, provided concrete evidence that this catalytic activation is based on halogen bonding. Thus, the results obtained in this study demonstrate that iodoalkynes can serve as a new scaffold for future development of halogen bonding catalysis.
- Matsuzawa, Akinobu,Takeuchi, Shiho,Sugita, Kazuyuki
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supporting information
p. 2863 - 2866
(2016/10/25)
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- Sulfur promoted decarboxylative thioamidation of carboxylic acids using formamides as amine proxy
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An efficient decarboxylative thioamidation of arylacetic and cinnamic acids has been developed employing formamides as amine surrogate and sulfur as promoter. Thioamides with variant structural features are obtained under mild reaction conditions without the use of transition metal catalysts and oxidants.
- Kumar, Saurabh,Vanjari, Rajeshwer,Guntreddi, Tirumaleswararao,Singh, Krishna Nand
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p. 2012 - 2017
(2016/04/05)
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- A copper(II)-thioamide combination as a robust heterogeneous catalytic system for green synthesis of 1,4-disubstituted-1,2,3-triazoles under click conditions
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An efficient and practical synthesis of 1,4-disubstituted-1,2,3-triazoles under click conditions using a copper(ii)-thioamide combination as an efficient heterogeneous catalyst is disclosed. Mild reaction conditions and high yields make this method an attractive option for the preparation of triazole derivatives. The key to this procedure was the generation of Cu(I) required for the azide-alkyne cycloaddition, which was achieved by in situ reduction of Cu(II) using thiobenzanilide as reduction agent and ligand.
- Mirjafary, Zohreh,Ahmadi, Leila,Moradi, Masomeh,Saeidian, Hamid
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p. 78038 - 78046
(2015/09/28)
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- Organocatalytic, difluorocarbene-based S-difluoromethylation of thiocarbonyl compounds
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Upon treatment with trimethylsilyl 2,2-difluoro-2-fluorosulfonylacetate (TFDA) and a catalytic amount of N,N,N′,N′-tetramethyl-1,8-diaminonaphthalene, secondary thioamides and thiocarbamates undergo selective difluoromethylation on the sulfur atom to give S-difluoromethyl thioimidates and thioiminocarbonates in good yields, respectively. This is the first report on the synthesis of acyclic difluoromethyl thioimidates and thioiminocarbonates. The key for S-difluoromethylation is the organocatalytic generation of difluorocarbene (:CF2) under mild conditions, which prevents decomposition of the substrates. This process provides an efficient approach to pharmaceuticals and agrochemicals bearing a difluoromethylsulfanyl group, starting from widely available thiocarbonyl compounds.
- Fuchibe, Kohei,Bando, Masaki,Takayama, Ryo,Ichikawa, Junji
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p. 133 - 138
(2015/03/04)
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- External Oxidant-Free Oxidative Cross-Coupling: A Photoredox Cobalt-Catalyzed Aromatic C-H Thiolation for Constructing C-S Bonds
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An external oxidant-free oxidative coupling for aromatic C-H thiolation by visible-light photoredox cobalt-catalysis has been developed. Various substrates could afford benzothiazoles in good to excellent yields, and only H2 is generated as a side product. When catalytic TBAOH was used as the base, not only 2-aryl but also 2-alkylbenzothiazoles could be obtained through this novel dehydrogenative coupling reaction. This method could be scaled up and applied to the synthesis of biologically active molecules bearing benzothiazole structural scaffolds (potent antitumor agents). Furthermore, the unexpected oxidation byproduct amides, which are often generated in oxidative cyclization of thiobenzanilides, can be completely avoided. Mechanistic studies showed that the H2 originates from the substrates. The kinetic studies indicate that the interaction between the cobalt catalyst and proton might be involved in the rate-limiting process. (Chemical Equation Presented).
- Zhang, Guoting,Liu, Chao,Yi, Hong,Meng, Qingyuan,Bian, Changliang,Chen, Hong,Jian, Jing-Xin,Wu, Li-Zhu,Lei, Aiwen
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supporting information
p. 9273 - 9280
(2015/08/11)
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- Decomposition of benzoylthioureas into benzamides and thiobenzamides under solvent-free conditions using iodine-alumina as the catalyst and its mechanistic study by density functional theory
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The breaking down of benzoylthioureas to benzamides and thiobenzamides in a single route using iodine-alumina as the catalyst under solvent-free conditions is highlighted. Results show that when an electron donating group, such as the methyl or methoxy group, is at the para-position of the aryl group of 1, benzamide (2) is the favoured product. When an electron withdrawing group, such as the chlorine or nitro group, is at the para-position of the aryl group of 1, thiobenzamide (3) is the favoured product. From the study of the reaction mechanism, it may be postulated that the formation of benzamide is due to the migration of the aryl group, whereas the formation of thiobenzamide may be due to the migration of the phenyl group. Thus, a new method for the formation of benzamides and thiobenzamides was developed.
- Nahakpam, Lokendrajit,Chipem, Francis A. S.,Chingakham, Brajakishor S.,Laitonjam, Warjeet S.
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supporting information
p. 2240 - 2247
(2015/03/18)
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- Organocatalytic syntheses of benzoxazoles and benzothiazoles using aryl iodide and oxone via C-H functionalization and C-O/S bond formation
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An organocatalytic protocol for the syntheses of 2-substituted benzoxazoles and benzothiazoles is described from alkyl-/arylanilides and alkyl-/arylthioanilides using 1-iodo-4-nitrobenzene as catalyst and oxone as an inexpensive and environmentally safe terminal oxidant at room temperature in air via oxidative C-H functionalization and C-O/S bond formation. The procedure is simple and general and provides an effective route for the construction of functionalized 2-alkyl-/arylbenzoxazoles and 2-alkyl-/arylbenzothiazoles with moderate to high yields. The synthetic and mechanistic aspects have been described.
- Alla, Santhosh Kumar,Sadhu, Pradeep,Punniyamurthy, Tharmalingam
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p. 7502 - 7511
(2014/09/16)
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- Sulfonic acid functionalized nano Γ-Al 2O 3: A new, efficient, and reusable catalyst for synthesis of thioamides
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Sulfonic acid functionalized nano γ-Al2O3 is easily prepared by the reaction of nano γ-Al2O3 with 1,3-propane sulfone. This reagent can be used as an eficient catalyst for the synthesis of thioamides. This new method consistently has the advantages of excellent yields and short reaction times. Further, the catalyst can be recovered for several times.
- Yin, Zhikui,Zheng, Bin,Ai, Fang
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p. 1412 - 1420
(2013/10/08)
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- Nano n -propylsulfonated magnetic γ-Fe2O3 as an efficient and reusable catalyst for the synthesis of thioamides
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One-pot three-component reactions of aldehydes, amines, and sulfur are carried out in the presence of nano n-propylsulfonated magnetic γ-Fe2O3 as a catalyst for the synthesis of biologically interesting thioamide derivatives. The value of this catalytic method lies in its mild reaction catalyst and conditions, good yields, and ease of handling.
- Yin, Zhikui,Zheng, Bin
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p. 527 - 531
(2013/10/21)
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- Synthesis of thioamides by catalyst-free three-component reactions in water
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Three-component reactions involving amines, aldehydes, and elemental sulfur powder are reported to afford thioamides in a simple one-pot procedure in the absence of a catalyst. A variety of thioamides can be obtained in good to excellent yields up to 88 %. Three-component reactions involving amines, aldehydes, and sulfur powder afford thioamides in a simple one-pot procedure. A variety of substituted thioamides are obtained in good to excellent yields up to 88 %. Copyright
- Xu, Hualong,Deng, Hang,Li, Zhengkai,Xiang, Haifeng,Zhou, Xiangge
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supporting information
p. 7054 - 7057
(2013/11/06)
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- Sulfated tungstate: An efficient catalyst for synthesis of thioamides via Kindler reaction
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New application of sulfated tungstate, a mildly acidic solid inorganic acid, as reusable heterogeneous catalyst for efficient Kindler reaction, a three component reactions of aldehydes, amines and sulfur, for synthesis of thioamides is discussed.
- Pathare, Sagar P.,Chaudhari, Pramod S.,Akamanchi, Krishnacharya G.
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experimental part
p. 125 - 129
(2012/07/03)
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- A THIONATION PROCESS AND A THIONATING AGENT
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A process for transforming a group >C=O (I) in a compound into a group >C=S (II) or into a tautomeric form of group (II) in a reaction giving a thionated reaction product, by use of crystalline P2S5·2 C5H5N as a thionating agent. A thionating agent which is crystalline P2S5·2 C5H5N
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Page/Page column 13
(2012/08/27)
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- A thionation process and a thionating agent
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A process for transforming a group >C=O (I) in a compound into a group >C=S (II) or into a tautomeric form of group (II) in a reaction giving a thionated reaction product, by use of crystalline P2S5·2 C5H5N as a thionating agent. A thionating agent which is crystalline P2S5·2 C5H5N.
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Page/Page column 8
(2012/08/14)
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- Facile synthesis of thioamides via P2S5-mediated beckmann rearrangement of oximes
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A facile and efficient approach to the synthesis of secondary thioamides from ketoximes via Beckmann rearrangement has been established, using phosphorus pentasulfide as a dehydrating and thiating agent. It is also efficient for the preparation of primary thiobenzamide from benzaldoxime. This approach features simple-operation, easy-control and good to excellent yields.
- Li, Jiangsheng,Cheng, Chao,Zhang, Xinrui,Li, Zhiwei,Cai, Feifei,Xue, Yuan,Liu, Weidong
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p. 1687 - 1689
(2012/10/29)
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- Microwave-assisted synthesis of thioamides with elemental sulfur
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Thioamides are prepared in moderate-to-good yields from the benzylamines or benzylamine derivatives by treatment with elemental sulfur under microwave and solvent-free conditions at 170.C in 15 min.
- Milen, Matyas,Abranyi-Balogh, Peter,Dancso, Andras,Keglevich, Gyoergy
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experimental part
p. 33 - 41
(2012/07/01)
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- O,O-Diethyl dithiophosphoric acid mediated direct synthesis of thioamides from aldehydes and ketones
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A general and convenient method for a one-pot conversion of aldehydes and ketones into thioamides has been developed. The protocol involves oximation of aldehydes and ketones followed by deoxygenative thioamidation of oximes with O,O-diethyl dithiophosphoric acid which acts as an acid as well a source of sulfur. The method is operationally simple, high yielding, and also applicable to the conversion of amides and nitriles into the corresponding thioamides.
- Yadav, Arvind K.,Srivastava, Vishnu P.,Yadav, Lal Dhar S.
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p. 7113 - 7116
(2013/01/15)
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- Friedel-Crafts-type reactions with ureas and thioureas
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Despite the relatively low reactivities of urea and thiourea functional groups towards nucleophilic attack, we have found conditions in which they are useful substrates in Friedel-Crafts reactions. The Bronsted superacid, triflic acid, promotes these reactions and a mechanism is proposed involving dicationic, superelectrophilic intermediates.
- Raja, Erum K.,Nilsson Lill, Sten O.,Klumpp, Douglas A.
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supporting information; experimental part
p. 8141 - 8143
(2012/09/07)
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- Highly selective mono-N-benzylation and amidation of amines with alcohols or carboxylic acids using the Ph2PCl/I2/imidazole reagent system
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Chlorodiphenylphosphine, imidazole, and molecular iodine in refluxing dichloromethane are used for the efficient preparation of amides under mild reaction conditions. This reagent system also shows excellent selectivity for mono-N-alkylation of amines with alcohols. In this system, the resulting phosphorus byproduct (diphenylphosphinic acid) is easily removed by extraction using an aqueous basic solution in the workup processes, which avoids the tedious and time-consuming chromatographic methods.
- Nowrouzi, Najmeh,Jonaghani, Mohammad Zareh
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experimental part
p. 498 - 509
(2012/07/30)
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- Facile and odorless one-pot process for the synthesis of N-substituted thioamides via TsCl-mediated Beckmann rearrangement of ketoximes
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A facile and odorless one-pot thionation process for the synthesis of N-substituted thioamides using chemically stable and inexpensive thiourea reagent via the Beckmann rearrangement of ketoximes, has been described. Georg Thieme Verlag Stuttgart · New York.
- Liu, Li-Feng,An, Na,Pi, Hong-Jun,Ying, Jun,Du, Wenting,Deng, Wei-Ping
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supporting information; experimental part
p. 979 - 981
(2011/06/11)
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- Thionations using a P4S10-pyridine complex in solvents such as acetonitrile and dimethyl sulfone
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Tetraphosphorus decasulfide (P4S10) in pyridine has been used as a thionating agent for a long period of time. The moisture-sensitive reagent has now been isolated in crystalline form, and the detailed structure has been determined by X-ray crystallography. The thionating power of this storable reagent has been studied and transferred to solvents such as acetonitrile in which it has proven to be synthetically useful and exceptionally selective. Its properties have been compared with the so-called Lawesson reagent (LR). Particularly interesting are the results from thionations at relatively high temperatures (165 °C) in dimethyl sulfone as solvent. Under these conditions, for instance, acridone and 3-acetylindole could quickly be transformed to the corresponding thionated derivatives. Glycylglycine similarly gave piperazinedithione. At these temperatures, LR is inefficient due to rapid decomposition. The thionated products are generally cleaner and more easy to obtain because in the crystalline reagent, impurities which invariably are present in the conventional reagents, P4S 10 in pyridine or LR, have been removed. 2011 American Chemical Society.
- Bergman, Jan,Pettersson, Birgitta,Hasimbegovic, Vedran,Svensson, Per H.
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experimental part
p. 1546 - 1553
(2011/06/11)
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- Ammonium phosphorodithioate: A mild, easily handled, efficient, and air-stable reagent for the conversion of amides into thioamides
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A simple, efficient, and new method has been developed for the synthesis of thioamides from amides. As described below, the reaction of a variety of aromatic and aliphatic amides in the presence of ammonium phosphorodithioate as an efficient reagent proceeded effectively to afford the corresponding thioamides in high yields. This method is easy, rapid, and high-yielding for the synthesis of thioamides from amides using an easily handled reagent. Georg Thieme Verlag Stuttgart · New York.
- Kaboudin, Babak,Malekzadeh, Leila
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experimental part
p. 2807 - 2810
(2012/01/02)
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- P4S10/dimethicone tandem: Efficient reagent for thionation of various aromatic amides and esters
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Organosulfur compounds are valuable because of their rich and varied chemistry especially in biological field. We report a new and efficient way for thionation of various aromatic amides and esters using P4S 10/ dimethicone tandem. The ease of handling and higher yield makes this protocol economical.
- Cho, Dongho,Ahn, Jiyoung,De Castro, Kathlia A.,Ahn, Hyunseok,Rhee, Hakjune
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supporting information; experimental part
p. 5583 - 5588
(2010/10/02)
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- A convenient one-pot preparation of N-substituted thioamides
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A convenient one-pot preparation of N-substituted thioamides from acyl halides, amines and H2O/PSCl3/Et3N in good to excellent yield has been reported through a solvent-free, microwave assisted method.
- Pandey, Lokesh Kumar,Pathak, Uma,Mazumder, Avik,Mathura, Sweta
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experimental part
p. 1225 - 1228
(2010/12/20)
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- New heteroaromatic azo compounds based on pyridine, isoxazole, and benzothiazole for efficient and highly selective amidation and mono-N-benzylation of amines under Mitsunobu conditions
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4,4′-Azopyridine (2c) is used in conjunction with triphenylphosphine for the efficient conversion of carboxylic acids into amides via Mitsunobu reaction with primary and secondary aliphatic and aromatic amines. The highly selective amidation of only primary aromatic amines with new heterogeneous azo compounds based on benzothiazole 2d and isoxazole 2e is also described. These azo compounds 2c-2e can also be applied for selective mono-N-benzylation of primary aromatic amines. The solid side product heteroaromatic hydrazines obtained under the developed Mitsunobu conditions are easily separated by simple filtration and can be reoxidized to azo compounds for further use.
- Iranpoor, Nasser,Firouzabadi, Habib,Khalili, Dariush
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scheme or table
p. 923 - 934
(2010/10/01)
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- Copper iodide as a recyclable catalyst for Buchwald N-arylation
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An experimentally simple, efficient, and inexpensive catalyst system was developed for the N-arylation of indole, substituted indoles, pyrazole, imidazole, benzamide, morpholine, benzimidazole, thiobenzamide, aniline, benzylaniline, octylaniline, heptylaniline, and cyclohexylaniline with aryl iodides and bromides by using CuI as catalyst, trans-1,2-diaminocyclohexane (L1) as ligand, K2CO3 as base, and water as solvent at 80 °C. The yields were excellent, and the catalytic system was recyclable up to four times without loss of catalytic activity. Arylated amines are green protocol that avoids hazardous and moisture-sensitive catalysts. The catalytic system can be recycled up to four times without loss of catalytic activity. Copyright
- Swapna, Kokkirala,Murthy, Sabbavarapu Narayana,Nageswar, Yadavalli Venkata Durga
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experimental part
p. 6678 - 6684
(2011/02/25)
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- Ketoximes to N-substituted thioamides via PSCl3 mediated Beckmann rearrangement
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N-Substituted thioamides were accessed from ketoximes by utilising PSCl3 as a uniquely capable reagent to induce Beckmann rearrangement as well as to capture the intermediate nitrilium ion. The Royal Society of Chemistry 2009.
- Pathak, Uma,Pandey, Lokesh Kumar,Mathur, Sweta,Suryanarayana
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scheme or table
p. 5409 - 5411
(2009/12/08)
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- Recyclable heterogeneous iron catalyst for C-N cross-coupling under ligand-free conditions
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(Chemical Equation Presented) An efficient and ligand-free C-N cross-coupling of aryl halides with various heterocycles using Fe/Cg as a recyclable catalyst is reported. The yields are excellent to moderate. 2009 American Chemical Society.
- Swapna,Vijay Kumar,Prakash Reddy,Rama Rao
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supporting information; experimental part
p. 7514 - 7517
(2009/12/28)
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- Conversion of thiobenzamides to benzothiazoles via intramolecular cyclization of the aryl radical cation
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A new and general method has been developed for the intramolecular cyclization of thiobenzamides to benzothiazoles via aryl radical cations as reactive intermediates. The method utilizes phenyliodine(III) bis(trifluoroacetate) (PIFA) in trifluoroethanol or cerium ammonium nitrate (CAN) in aqueous acetonitrile at room temperature to effect cyclization within 30 min in moderate yields.
- Downer-Riley, Nadale K.,Jackson, Yvette A.
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p. 7741 - 7744
(2008/12/20)
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- Efficient synthesis of thiobenzanilides by Willgerodt-Kindler reaction with base catalysts
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Willgerodt-Kindler reaction between anilines and benzaldehydes readily proceeded in the presence of catalytic amount of Na2S·9H 2O to give thiobenzanilides in moderate to good yields. The base catalyst was also available for preparation of primary thiobenzamide. Georg Thieme Verlag Stuttgart.
- Okamoto, Ken,Yamamoto, Takakazu,Kanbara, Takaki
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p. 2687 - 2690
(2008/02/11)
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- Lawesson's reagent for direct thionation of hydroxamic acids: Substituent effects on LR reactivity
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To explore the generality and scope of direct thionation of hydroxamic acids (HAs), the reaction of various structurally diverse HAs with Lawesson's reagent was investigated. The yield of thiohydroxamic acid (THAs) is poor when HAs possess bulky acyl and/or N-substituents, acidic α-hydrogen atoms, or an N-phenyl ring. THAs yields were correlated with Brown sigma parameter. The relative rates of two subsequent processes kT2 and kR2 were also measured. Correlation was also found for methine proton chemical shifts of N-isopropyl benzothiohydroxamic acids.
- Przychodzen, Witold
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p. 676 - 684
(2007/10/03)
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- Synthesis of S-thioacyl dithiophosphates, efficient and chemoselective thioacylating agents
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Easily available acyl dithiophosphates are not stable and isomerise reversibly to O-thioacyl monothiophosphates, especially when subjected to heating. Much slower but probably irreversible isomerisation to S-thioacyl monothiophosphates occurs. Since equilibrium states are established and S-thioacyl (mono)thiophosphates form slowly, reaction mixtures contain generally both thioacylating and acylating agents, and consequently cannot be used for efficient thioacylation. On the other hand, treatment of a mixture of isomeric anhydrides with an excess of a dithiophosphoric acid leads to exclusive formation of S-thioacyl dithiophosphates. They appear to be excellent thioacylating agents: relatively stable, inert towards water and oxygen and therefore easy to handle. Reactions with nitrogen or sulfur nucleophiles proceed very rapidly under ambient conditions, yielding respective thioacyl derivatives. Isolation of the products is very simple. Due to the low reactivity of S-thioacyl dithiophosphates towards oxygen nucleophiles they can be used for direct thioacylation of multifunctional nucleophiles with unprotected hydroxy groups. Respective thioacyl derivatives cannot readily be obtained using other methods.
- Doszczak, Leszek,Rachon, Janusz
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p. 1271 - 1279
(2007/10/03)
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- Facile preparation of amides from thioamides by ceric ammonium nitrate
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Ceric ammonium nitrate (CAN) is found to be a good oxidizing agent which converts thioamides into their oxygen analogues in aqueous acetic acid under very mild conditions.
- Movassagh, Barahman,Meibodi, Forhatosadat,Sobhani, Shahin
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p. 1296 - 1298
(2007/10/03)
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- Attempted synthesis of 2-azetidinones via ester enolate condensation reactions with imines and thioimidates
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Reaction of the imines 1 and ethyl isobutyrate in the presence of LDA yields β-lactams 2, whereas thioimidate 4 with the same enolate gives the substituted products 5. When phosphorous containing heterocyclic compound 9 is treated with the enolate of ethyl isobutyrate, a mixture of substituted products 10 and 11 is produced. Mechanistic details of these reactions are described.
- Sharma,Saluja, Aarti,Bhaduri, Susmita,Kanwar, Seema
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p. 1964 - 1969
(2007/10/03)
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- Thionation with the reagent combination of phosphorus pentasulfide and hexamethyldisiloxane
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The combination of P4S10 and hexamethyldisiloxane efficiently converts esters, lactones, amides, lactams, and ketones to their corresponding thiono derivatives. In the presence of elemental sulfur, 3-oxoesters are converted to dithiolethiones by this reagent. Yields are comparable to or superior to those obtained with Lawesson's reagent. The method has the advantage that reagent-derived byproducts may be removed by a simple hydrolytic workup or by filtration through silica gel, rather than by chromatography, as required for Lawesson's reagent.
- Curphey, Thomas J.
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p. 6461 - 6473
(2007/10/03)
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- New, efficient and chemoselective method of thioacylation, starting from carboxylic acids
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S-Acylation of dithiophosphoric acids yields mixed anhydrides 3; they readily isomerize to O-thioacyl 4 and S-thioacyl monothiophosphates 5, which treated with the excess of dithiophosphoric acid 2 can be easily converted into thioacyl dithiophosphates 6, excellent thioacylating reagents.
- Doszczak,Rachon
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p. 2093 - 2094
(2007/10/03)
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- Microwave-accelerated solvent-free synthesis of thioketones, thiolactones, thioamides, thionoesters, and thioflavonoids
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Formula presented An expeditious, solvent-free, and high yield conversion of ketones, flavones, isoflavones, lactones, amides, and esters to the corresponding thio analogues is described utilizing Lawesson's reagent in a process that circumvents the use of dry solvents and excess of the reagent.
- Varma, Rajender S.,Kumar, Dalip
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p. 697 - 700
(2008/02/11)
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