- Electrochemically enabled rhodium-catalyzed [4 + 2] annulations of arenes with alkynes
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Herein, electrochemically driven, Rh(iii)-catalyzed regioselective annulations of arenes with alkynes have been established. The strategy, combining the use of a rhodium catalyst with electricity, not only avoids the need for using a stoichiometric amount of external oxidant, but also ensures that the transformations proceed under mild and green conditions, which enable broad functional group compatibility with a variety of substrates, including drugs and pharmaceutical motifs. Moreover, the electrolysis reaction was made operationally simple by employing an undivided cell, and proceeds efficiently in aqueous solution in air. This journal is
- Chen, Jia-Yi,Li, Ming,Li, Rui-Tao,Ma, Qiang,Ni, Shao-Fei,Wang, Zi-Chen,Wen, Li-Rong,Zhang, Lin-Bao
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supporting information
p. 9515 - 9522
(2021/12/09)
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- Water-Tolerant ortho-Acylation of Phenols
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A metal-free, water-tolerant, and one-pot process for ortho-acylation of phenols promoted by the iodine source/hydrogen peroxide system has been developed. This transformation undergoes ether formation, iodocyclization, C-C bond cleavage, and oxidative hydrolysis in a one-step manner, which is supported by control experiments.
- Tian, Jie-Sheng,He, Yu,Gao, Zhi-Yuan,Liu, Xu,Dong, Shuang-Feng,Wu, Peng,Loh, Teck-Peng
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supporting information
p. 6594 - 6598
(2021/09/02)
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- Synthesis of pterocarpans through palladium-catalyzed oxyarylation of alkoxy-2H-chromenes with o-iodophenols
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The oxyarylation of alkoxy-2H-chromenes (1a-e) with o-iodophenols substituted by electron-withdrawing (CHO) and electron-donating (OMe) groups is studied under two experimental conditions: a) Pd(OAc)2, Ag2CO3 in PEG-400 at 140 °C, 10 min and b) oxime-based palladacycle, DIPEA, in PEG-400 at 150 °C, 3–4 h. Pterocarpans are obtained in moderate to good chemical yields.
- Gaspar, Francisco V.,Barcellos, Julio C.F.,Cívicos, José F.,Merino, Pedro,Nájera, Carmen,Costa, Paulo R.R.
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- Kojic acid–natural product conjugates as mushroom tyrosinase inhibitors
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As part of our effort to develop potential tyrosinase inhibitors, we have conjugated the well-known tyrosinase inhibitor kojic acid (KA) with several phenolic natural products such as umbelliferone, sesamol, thymol, carvacrol, eugenol, isoeugenol, vanilli
- Ashooriha, Morteza,Emami, Saeed,Kardan, Mostafa,Khoshneviszadeh, Mahsima,Khoshneviszadeh, Mehdi,Rafiei, Alireza,Yazdian-Robati, Rezvan
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- Copper-Catalyzed Ring Opening of [1.1.1]Propellane with Alkynes: Synthesis of Exocyclic Allenic Cyclobutanes
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Despite the long history and interesting properties of propellanes, these compounds still have tremendous potential to be exploited in synthetic organic chemistry. Herein we disclose an experimentally simple procedure to achieve cyclobutane-containing allenes and alkynes through a copper-catalyzed ring opening of [1.1.1]propellane and subsequent reaction with ethynes.
- Lasányi, Dániel,Tolnai, Gergely L.
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supporting information
p. 10057 - 10062
(2019/12/24)
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- Thermally Induced Denitrogenative Annulation for the Synthesis of Dihydroquinolinimines and Chroman-4-imines
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A rapid growth in synthetic methods for the preparation of diverse organic molecules using N-sulfonyl-1,2,3-triazoles is of great interest in organic synthesis. Transition metals are generally used to activate the α-imino diazo intermediates. Metal-free methods have not been studied in detail, but can be a good complement to transition metal catalysis in the mild reaction conditions. We herein report a novel method for the preparation of 2,3-dihydroquinolin-4-imine and chroman-4-imine analogs from their corresponding N-sulfonyl-1,2,3-triazoles in the absence of metal catalysts. To achieve intramolecular annulation, the introduction of an electron-donating group is required at the meta position of N-sulfonyl-1,2,3-triazole methyl anilines. The inclusion of tailored substituents on the aniline moieties and nitrogen atoms enhances the nucleophilicity of the phenyl π-electrons, thus allowing them to undergo a Friedel-Crafts-type reaction with the highly electrophilic ketenimines. This metal-free method was carefully optimized to generate a variety of dihydroquinolin-4-imines and chroman-4-imines in moderate-to-good yields.
- Chou, Chih-Hung,Chen, Ying-Yu,Rajagopal, Basker,Tu, Hsiu-Chung,Chen, Kuan-Lin,Wang, Sheng-Fu,Liang, Chien-Fu,Tyan, Yu-Chang,Lin, Po-Chiao
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supporting information
p. 757 - 765
(2016/03/09)
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- Synthesis of substituted 3-methylene-2,3-dihydrobenzofurans and 3-methylbenzofurans by rhodium (II)-catalyzed annulation
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Abstract The selective synthesis of substituted 3-methylene-2,3-dihydrobenzofurans and 3-methylbenzofurans has developed through Rh(II)-catalyzed denitrogenative annulation of N-sulfonyl-1,2,3-triazole at ambient to mild heating condition, respectively. F
- Chen, Ying-Yu,Chen, Kuan-Lin,Tyan, Yu-Chang,Liang, Chien-Fu,Lin, Po-Chiao
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p. 6210 - 6218
(2015/08/03)
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- Semi-synthesis and biological evaluation of 1,2,3-triazole-based podophyllotoxin congeners as potent antitumor agents inducing apoptosis in HepG2 cells
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A series of 4β-[(4-substituted)-1,2,3-triazol-1-yl]podophyllotoxin congeners were synthesized by employing click chemistry and further evaluated for their antitumor activity by MTT assay. Among them, six congeners (10, 11, 12, 13, 22, and 24) exhibited ap
- Chen, Jinying,Ma, Liang,Zhang, Ronghong,Tang, Jie,Lai, Huijun,Wang, Jun,Wang, Guangcheng,Xu, Qinyuan,Chen, Tao,Peng, Fei,Qiu, Jingxiang,Liang, Xiaolin,Cao, Dong,Ran, Yan,Peng, Aihua,Wei, Yuquan,Chen, Lijuan
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p. 945 - 956
(2013/02/22)
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- SUBSTITUTED ALKYNYL PHENOXY COMPOUNDS AS NEW SYNERGISTS IN PESTICIDAL COMPOSITIONS
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A composition comprising an alkynyl phenoxy compound of Formula (I) as a synergist and a pesticidal active ingredient is described, wherein R1 and R2, similar or different, are (C1-C4)alkyl or R1O- an
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Page/Page column 19
(2011/04/13)
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- Substituted alkynyl phenoxy compounds and their uses
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An alkynyl phenoxy compound of Formula (I) is described, wherein R1 and R2, similar or different, are (C1-C4)alkyl or R1O- and R2O- together represent a group -O-CH2-O-, -O-CH(CH
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Page/Page column 10
(2011/04/14)
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- Intramolecular reactions of alkynes with furans and electron rich arenes catalyzed by PtCl2: The role of platinum carbenes as intermediates
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5-(2-Furyl)-1-alkynes react, with PtCl2 as catalyst, to give phenols. On the basis of DFT calculations, a cyclopropyl platinacarbene complex was found as the key intermediate in the process. The cyclopropane and dihydrofuran rings of this intermediate open to form a carbonyl compound, which reacts with the platinum carbene to form an oxepin, which is in equilibrium with an arene oxide. When the reaction is carried out in the presence of water, dicarbonyl compounds are obtained, which support the proposed mechanism. Other cyclizations of alkynes with furans or electron-rich arenes give products of apparent Friedel-Crafts-type reactions, although these processes could also proceed by pathways involving the formation of cyclopropyl platinum carbenes.
- Martin-Matute, Belen,Nevado, Cristina,Cardenas, Diego J.,Echavarren, Antonio M.
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p. 5757 - 5766
(2007/10/03)
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- Biological Activity of Pyrethroid Analogs in Pyrethroid-Susceptible and -Resistant Tobacco Budworms, Heliothis virescens (F.)
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The phenoxybenzyl moiety of conventional pyrethroids is a major site of oxidative metabolism in resistant tobacco budworms, Heliothis virescens (F.). In this study, this group was replaced with known P450 monooxygenase-inhibiting or oxidatively blocked groups. A variety of isomers (1R/1S, cis/trans) of the resulting chrysanthemates were tested as insecticides or synergists against tobacco budworms that were insecticide-susceptible (LSU) or that expressed metabolic resistance to cypermethrin (Pyr-R). A number of compounds with pentafluorophenyl, methylenedioxyphenyl, and propargyloxyphenyl groups were insecticidal, and activity was dependent on both geometric and stereochemical configuration of the acid moiety. Both trans and cis isomers of 1(R)-fenfluthrin, which contains a pentafluorophenyl group, suppressed resistance to cypermethrin in Pyr-R insects, confirming that oxidative metabolism of the phenoxybenzyl moiety is a major mechanism of resistance in this strain. Of the methylenedioxyphenyl compounds, 1R, trans, and cis isomers were toxic and partially suppressed resistance in Pyr-R larvae. Similarly, both trans and cis isomers of α(S),1(R)-propargyloxyphenyl-containing compounds were insecticidal. Finally, α(R),1(R)-cis-methylenedioxyphenyl- and -propargyloxyphenyl- containing compounds were nontoxic but significantly enhanced toxicity of cypermethrin.
- Shan, Guomin,Hammer, Robert P.,Ottea, James A.
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p. 4466 - 4473
(2007/10/03)
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