- Activator free, expeditious and eco-friendly chlorination of activated arenes by N-chloro-N-(phenylsulfonyl)benzene sulfonamide (NCBSI)
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N-Chloro-N-(phenylsulfonyl)benzene sulfonamide (NCBSI) has been explored for the first time as a chlorinating reagent for direct chlorination of various activated arenes and heterocycles without any activator. A comparative in-silico study was performed to determine the electrophilic character for NCBSI and commercially available N-chloro reagents to reveal the reactivity on a theoretical viewpoint. The reagent was prepared by an improved method avoiding the use of hazardous t-butyl hypochlorite. This reagent was proved to be very reactive compared to other N-chloro reagents. The precursor of the reagent N-(phenylsulfonyl)benzene sulfonamide was recovered from aqueous spent, which can be recycled to synthesize NCBSI. The eco-friendly protocol was equally applicable for the synthesis of industrially important chloroxylenol as an antibacterial agent.
- Misal, Balu,Palav, Amey,Ganwir, Prerna,Chaturbhuj, Ganesh
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supporting information
(2021/01/04)
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- Ammonium Salt-Catalyzed Highly Practical Ortho-Selective Monohalogenation and Phenylselenation of Phenols: Scope and Applications
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An ortho-selective ammonium chloride salt-catalyzed direct C-H monohalogenation of phenols and 1,1′-bi-2-naphthol (BINOL) with 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) as the chlorinating agent has been developed. The catalyst loading was low (down to 0.01 mol %) and the reaction conditions were very mild. A wide range of substrates including BINOLs were compatible with this catalytic protocol. Chlorinated BINOLs are useful synthons for the synthesis of a wide range of unsymmetrical 3-aryl BINOLs that are not easily accessible. In addition, the same catalytic system can facilitate the ortho-selective selenylation of phenols.
- Xiong, Xiaodong,Yeung, Ying-Yeung
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p. 4033 - 4043
(2018/05/22)
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- Regioselective C-H chlorination: Towards the sequential difunctionalization of phenol derivatives and late-stage chlorination of bioactive compounds
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We have developed a protocol for the auxillary directed C-H chlorination of phenol derivatives using catalytic amounts of palladium acetate that is amenable to the late-stage chlorination of diflufenican and estrone. The 2-pyridine group allows for a highly efficient palladium-catalyzed chlorination and sequential ortho C-H functionalization reaction of phenol derivatives to produce a variety of symmetrical and unsymmetrical 2,4,6-trisubstituted phenols.
- Gao, Chao,Li, Hongchen,Liu, Miaochang,Ding, Jinchang,Huang, Xiaobo,Wu, Huayue,Gao, Wenxia,Wu, Ge
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p. 46636 - 46643
(2017/10/16)
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- Direct spectroscopic observation of closed-shell singlet, open-shell singlet, and triplet p -biphenylyloxenium ion
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The photophysics and photochemistry of p-biphenylyl hydroxylamine hydrochloride was studied using laser flash photolysis ranging from the femtosecond to the microsecond time scale. The singlet excited state of this photoprecursor is formed within 350 fs and partitions into three different transients that are assigned to the p-biphenyloxy radical, the open-shell singlet p-biphenylyloxenium ion, and the triplet p-biphenylyloxenium ion, having lifetimes of 40 μs, 45 ps, and 1.6 ns, respectively, in CH3CN. The open-shell singlet p-biphenylyloxenium ion predominantly undergoes internal conversion to produce the closed-shell singlet p-biphenylyloxenium ion, which has a lifetime of 5-20 ns. The longer-lived radical is unambiguously assigned by nanosecond time-resolved resonance Raman (ns-TR3) spectroscopy, and the assignment of the short-lived singlet and triplet oxenium ion transient absorptions are supported by matching time-dependent density functional theory (TD-DFT) predictions of the absorptions of these species, as well as by product studies that implicate the intermediacy of charged electrophilic intermediates. Product studies from photolysis give p-biphenylol as the major product and a chloride adduct as the major product when NaCl is added as a trap. Thermolysis studies give p-biphenylol as a major product, as well as water, ammonium, and chloro adducts. These studies provide a rare direct look at a discrete oxenium ion intermediate and the first detection of open-shell singlet and triplet configurations of an oxenium ion, as well as providing an intriguing example of the importance of excited state dynamics in governing the electronic state population of reactive intermediates.
- Li, Ming-De,Hanway, Patrick J.,Albright, Toshia R.,Winter, Arthur H.,Phillips, David Lee
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p. 12364 - 12370
(2014/12/09)
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- Synthesis of o-chlorophenols via an unexpected nucleophilic chlorination of quinone monoketals mediated by N,N′-dimethylhydrazine dihydrochloride
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An unexpected nucleophilic chlorination of a quinone monoketal while carrying out a pyrazolidine synthesis has led to a general preparation of multisubstituted phenols. The products are obtained in good to high yields under mild conditions. The bridged pyrazolidines that were the original targets are obtained in the presence of a protic solvent. This journal is the Partner Organisations 2014.
- Yin, Zhiwei,Zhang, Jinzhu,Wu, Jing,Green, Riana,Li, Sihan,Zheng, Shengping
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supporting information
p. 2854 - 2858
(2014/05/06)
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- Multisubstituted benzo[b]furans through a copper- and/or palladium-catalyzed assembly and functionalization process
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Full details as well as the study of the scope, limitations, and further elaboration of a straightforward approach to the synthesis of 2,5,7-trisubstituted benzo[b]furans from 2-bromo- and 2-chloro-6-iodo-4- substituted phenols through a consecutive copper- and/or palladium-catalyzed assembly and functionalization process is described. Functionalization at the C(7) position is carried out by Suzuki-Miyaura cross-coupling, alkynylation, alkenylation, and C-N bond forming reactions. A one-pot protocol for the synthesis of 2,5,7-trisubstituted benzo[b]furans is also reported.
- Arcadi, Antonio,Blesi, Federico,Cacchi, Sandro,Fabrizi, Giancarlo,Goggiamani, Antonella,Marinelli, Fabio
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p. 1857 - 1871
(2013/04/10)
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- 2,5,7-Trisubstituted benzo[b]furans through a copper- and/or palladium-catalyzed assembly and functionalization process
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A straightforward approach to the synthesis of 2,5,7-trisubstituted benzo[b]furans from 2-bromo- and 2-chloro-6-iodo-4-substituted phenols through a consecutive copper- and/or palladium-catalyzed assembly and functionalization process is described. Functionalization at the C(7) position is carried out by Suzuki-Miyaura cross-coupling and C-N bond forming reactions.
- Arcadi, Antonio,Blesi, Federico,Cacchi, Sandro,Fabrizi, Giancarlo,Goggiamani, Antonella
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scheme or table
p. 5149 - 5152
(2011/10/12)
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- Modular synthesis of indoles from imines and o-dihaloarenes or o-chlorosulfonates by a Pd-catalyzed cascade process
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A detailed study of the scope of a new Pd-catalyzed synthesis of indolesfrom 1,2-dihaloarenes and o-halobenzene sulfonates and imines is descri bed. The cascade reaction comprises an imine a-arylation ollowed by an intramolecular C-N bond-forming reaction promoted by the same Pd catalyst. The reaction with 1,2-dibromobenzene shows wide scope and allows the introduction of aryl, alkyl, and vinyl substituents at different positions of the five-membered ring of the indole. The regioselective synthesis of indoles substituted in the six-membered ring can be carried out by employing o-dihalobenzene derivatives with two different halogens, taking advantage of the different reactivities of I, Br, and Cl in oxidative addition reactions. This paper also introduces a method for the efficient cleavage of the N-t-butyl group, thus allowing for the preparation of N-H indoles through the same methodology. Finally, the reaction with o-halosulfonates has been studied. The best substrates are o-chlorononaflates, which lead to indoles in very high yield. The reaction is particularlyappropriate for the synthesis of the challenging 6-substituted indoles. In view of the availability of o-chlorophenols, which are direct precur sors of the chlorononaflates, this reaction represents an efficient entry into indoles substituted in the six-membered ring. The concept is illustrated by the preparation of a 4,6-disubstituted indole from naturally occurring anethole.
- Barluenga, Jose,Jimenez-Aquino, Agustin,Aznar, Fernando,Valdes, Carlos
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supporting information; experimental part
p. 4031 - 4041
(2009/09/04)
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- ERbeta ligands. Part 1: the discovery of ERbeta selective ligands which embrace the 4-hydroxy-biphenyl template.
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The synthesis and structure-activity relationships of a series of simple biphenyls is described. Optimization of the 4-hydroxy-biphenyl template led to compounds with ERbeta selectivity on the order of 20-70-fold.
- Edsall Jr., Richard J,Harris, Heather A,Manas, Eric S,Mewshaw, Richard E
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p. 3457 - 3474
(2007/10/03)
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- Ligandless palladium catalyzed reactions of arylboronic acids and sodium tetraphenylborate with aryl halides in aqueous media
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Polyfunctional biaryls are prepared by a modified Suzuki cross-coupling reaction between arylboronic acids or sodium tetraphenylborate and aryl halides ArX. X = 1. Br. Cl in aqueous solvents or neat water using a phosphine-free palladium catalyst, and in the presence of bases (Na2CO3 or NaOH). All four phenyl groups of Ph4BNa participate ill the reaction. The reaction of Ph4BNa with aryl halides proceeds in water with high catalytic efficiency (250,000 catalytic cycles).
- Bumagin, Nikolai A.,Bykov, Victor V.
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p. 14437 - 14450
(2007/10/03)
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- Reaction of Organoboron Compounds with Organic Halides in Aqueous Media, Catalyzed by "Ligand-Free" Palladium
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The results of investigations of the reactions between aryllboric acids or sodium tetraphenylborate and organic halides in water and DMF- and acetone-water mixtures, catalyzed by palladium salts containing no phosphine ligands [Pd(OAc)2, PdCl2], are considered.
- Bumagin,Bykov
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p. 1925 - 1938
(2007/10/03)
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