- A green procedure for the diazotization-iodination of aromatic amines under aqueous, strong-acid-free conditions
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A convenient and mild one-pot method for the synthesis of iodoarenes in high yields by the sequential diazotization-iodination of aromatic amines with a reusable polymeric diazotization agent in the presence of p-toluenesulfonic acid at room temperature in water was developed. The method is general and is the greenest alternative of the known diazotization-iodination methods. The method is also effective for the preparation of 1H-benzo[d][1,2,3]triazole and benzo[d][1,2,3]thiadiazole. Georg Thieme Verlag Stuttgart ? New York.
- Trusova, Marina E.,Krasnokutskaya, Elena A.,Postnikov, Pavel S.,Choi, Younghwa,Chi, Ki-Whan,Filimonov, Victor D.
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- Linear Hydroaminoalkylation Products from Alkyl-Substituted Alkenes
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The regioselective conversion of alkyl-substituted alkenes into linear hydroaminoalkylation products represents a strongly desirable synthetic transformation. In particular, such conversions of N-methylamine derivatives are of great scientific interest, because they would give direct access to important amines with unbranched alkyl chains. Herein, we present a new one-pot procedure that includes an initial alkene hydroaminoalkylation with an α-silylated amine substrate and a subsequent protodesilylation reaction that delivers linear hydroaminoalkylation products with high selectivity from simple alkyl-substituted alkenes. For that purpose, new titanium catalysts have been developed, which are able to activate the α-C?H bond of more challenging α-silylated amine substrates. In addition, a direct relationship between the ligand structure of the new catalysts and the obtained regioselectivity is described.
- Warsitz, Michael,Doye, Sven
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supporting information
p. 15121 - 15125
(2020/10/23)
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- Preparation method of 3,5-diphenylbromobenzene
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The invention belongs to the field of organic synthesis and provides a novel method of synthesizing 3,5-diphenylbromobenzene. 2,4,6-Tribromoaniline is used as a start material subjected to diazotization iodination and Grignard reaction to obtain 3,5-diphenylbromobenzene. Compared with traditional synthetic processes, the novel process has simple synthetic steps; the materials selected are easy toattain and low in price; the two reaction steps are easy to implement; the product yield is high; 3,5-diphenylbromobenzene is easy to industrially produce.
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Paragraph 0019; 0020; 0022; 0023; 0025; 0026
(2019/07/01)
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- Catalytic formal cycloadditions between anhydrides and ketones: Excellent enantio and diastereocontrol, controllable decarboxylation and the formation of adjacent quaternary stereocentres
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It has been shown for the first time that enolisable anhydrides can participate in highly efficient and diastereo/enantioselective additions to activated ketones. In these reactions the anhydride component formally acts (initially) as the nucleophilic component. These processes are promoted by novel, readily prepared urea-substituted cinchona alkaloid-derived catalysts at low loadings under mild conditions. Three classes of enolisable anhydride and three different types of activated ketone were shown to be compatible with the process-generating a diverse range of structurally distinct and densely functionalised lactone products with the formation of two new stereocentres, one of which is quaternary. In one example, a product incorporating two contiguous quaternary stereocentres (one all carbon) was formed with outstanding enantiocontrol. It has been shown in the case of glutaconic anhydride derivatives that the cycloaddtion process is reversible, and can be accompanied by decarboxylation and olefin isomerisation. Reaction conditions can be modified to give access to three types of product with good-excellent ee.
- Cornaggia, Claudio,Gundala, Sivaji,Manoni, Francesco,Gopalasetty, Nagaraju,Connon, Stephen J.
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supporting information
p. 3040 - 3046
(2016/03/19)
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- N-PHENYL TRISCARBAZOLE
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The present invention relates to a novel triscarbazole compound having substituent on N-phenyl, which can be represented by Formula (I). wherein R1 is selected from the group consisting of hydrogen, halogen or alkyl or alkoxy group having 1 to 20 carbon atoms wherein at least one hydrogen atom is optionally replaced by halogen; RA, RB, RC, RD and RE are any of substituents other than hydrogen wherein at least two of R1 and RA may further form a fused ring; and i, j, k, l and m are same or different at each occurrence and represent an integer from 0 to 4, with the proviso that when R1 is hydrogen, i is not 0. By introduction of the substituent on N-phenyl, the device efficiency, stability and lifetime can be increased while maintaining the solubility. These compounds can be used in various organic devices such as organic light emitting diodes, photovoltaic cells or organic semiconductor devices.
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Page/Page column 20-21
(2012/03/26)
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- Photoswitchable catalysts: Correlating structure and conformational dynamics with reactivity by a combined Experimental and computational approach
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Photocontrol of a piperidine's Bronsted basicity was achieved by incorporation of a bulky azobenzene group and could be translated into pronounced reactivity differences between ON- and OFF- states in general base catalysis. This enabled successful photomodulation of the catalyst's activity in the nitroaldol reaction (Henry reaction). A modular synthetic route to the photoswitchable catalysts was developed and allowed for preparation and characterization of three azobenzene-derived bases as well as one stilbene-derived base. Solid-state structures obtained by X-ray crystal structure analysis confirmed efficient blocking of the active site in the E isomer representing the OFF-states, whereas a freely accessible active site was revealed for a representative Z isomer in the crystal. To correlate structure with reactivity of the catalysts, conformational dynamics were thoroughly studied in solution by NMR spectroscopy, taking advantage of residual dipolar couplings (RDCs), in combination with comprehensive DFT computational investigations of conformations and proton affinities.
- Stoll, Ragnar S.,Peters, Maike V.,Kuhn, Andreas,Hecht, Stefan,Heiles, Sven,Thiele, Christina M.,Goddard, Richard,Buehl, Michael
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supporting information; experimental part
p. 357 - 367
(2009/06/18)
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- Unusually stable, versatile, and pure arenediazonium tosylates: Their preparation, structures, and synthetic applicability
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(Graph Presented) A new, simple, and effective method for the diazotization of a wide range of arylamines has been developed by using a polymer-supported diazotization agent in the presence of p-toluenesulfonic acid. Various pure arenediazonium tosylates with unusual stabilities can be easily prepared by this method. As a result, these salts are useful and versatile substrates for subsequent transformations, such as halogenation and Heck-type reactions. The unusual stabilities of arenediazonium tosylates are also preliminarily discussed with their X-ray structures.
- Filimonov, Victor D.,Trusova, Marina,Postnikov, Pavel,Krasnokutskaya, Elena A.,Lee, Young Min,Hwang, Ho Yun,Kim, Hyunuk,Chi, Ki-Whan
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supporting information; experimental part
p. 3961 - 3964
(2009/05/30)
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- Photoswitching of basicity
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(Figure Presented) Smart bases: By using a photochromic azobenzene-derived blocking group, a piperidine base can be switched between a sterically shielded, inactive form and an accessible, reactive form (see picture; C dark gray, H light gray, O red, N blue). Thus, light can be used for the reversible external modulation of ground-state basicity and hence activity in general base catalysis.
- Peters, Maike V.,Stoll, Ragnar S.,Kuehn, Andreas,Hecht, Stefan
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supporting information; experimental part
p. 5968 - 5972
(2009/03/11)
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- Anaerobic transformation of polybrominated biphenyls with the goal of identifying unknown hexabromobiphenyls in Baltic cod liver
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Polybrominated biphenyls (PBBs) have been introduced as flame retardants in 1970. Despite decreasing application rates since the mid-1970s, PBB residues are still reported in the environment. Furthermore, environmental PBB residues often do not match the PBB pattern in technical products. To get insights into the structures of environmentally-relevant PBBs, the congener patterns of technical hexabromobiphenyl (THBB), octabromobiphenyl (TOBB), synthesized PBB 209 were compared to PBB residues in a cod liver sample from the Baltic Sea. The most relevant PBB congeners in Baltic cod liver were not present in the technical products and therefore most likely metabolites. For this reason, TOBB and HPLC-fractions obtained from this technical product were incubated with super-reduced cyanocobalamine. Reductive debromination was found to be the predominant transformation process. Bromine substituents in ortho-positions proved to be more recalcitrant, and several of the unknown PBBs were tri- and tetra-ortho substituted congeners. Furthermore, the key-PBBs determined in Baltic cod liver were formed during this process. The most important hexabromobiphenyl in Baltic cod liver was identified as PBB 155 by parallel synthesis. PBB 155 which was not detected in the technical PBB product analyzed was suggested as an indicator PBB congener suited to decide whether PBB residues originate from the previous use of THBB (low relative abundance of PBB 155) or TOBB/TDBB (high relative abundance of PBB 155). The latter scenario was found to be valid for the Baltic cod liver sample. Thus, PBBs in the Baltic Sea appeared to originate from partially-weathered residues of PBB 209.
- von der Recke, Roland,Vetter, Walter
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p. 352 - 359
(2008/09/21)
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- A practical and efficient synthesis of 5′-substituted m-terphenyls
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Outlined is a simple, convenient, scalable procedure for the synthesis of a variety of 5′-substituted m-terphenyl compounds from commercially available materials. A series of novel compounds were generated based on the m-terphenyl scaffold. In addition we
- Kehlbeck, Joanne D.,Dimise, Eric J.,Sparks, Sarah M.,Ferrara, Skylar,Tanski, Joseph M.,Anderson, Craig M.
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p. 1979 - 1983
(2008/02/12)
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- 1-Aryl-3,3-dialkyltriazenes: A convenient synthesis from dry arenediazonium o-benzenedisulfonimides - A high yield break down to the starting dry salts and efficient conversions to aryl iodides, bromides and chlorides
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This research comprises three parts. The first part regards the synthesis of 1-aryl-3,3-dialkyltriazenes 3 by reaction of dry arenediazonium o-benzenedisulfonimides 1, also coming from weakly basic aromatic amines with dimethylamine or diethylamine in aqueous solution at 0-5 °C. Yields were usually greater than 90% and there was the possibility of recovering the o-benzenedisulfonimide (5), which could be reused to prepare the salts 1. In the second part it was demonstrated that there is the possibility of reconverting the triazenes 3 into the starting stable dry salts 1 by using 5 as acid. The reactions were carried out in glacial acetic acid at 50-55 °C and normally afforded salts 1 in yields of around 90-99%. The third part concerns the setting up of two procedures for the conversion of 3 to aryl iodides 9, bromides 10 and chlorides 11. Procedure A used the corresponding aqueous hydrogen halides in acetonitrile at r.t. or 60 °C, sometimes in the presence of aqueous HBF4, sometimes Cu powder (25 examples, yields 65%-88%). Procedure B usually used anhydrous methanesulfonic acid and tetraalkylammonium halides in anhydrous acetonitrile at temperatures varying from r.t. to 80 °C, sometimes in the presence of Cu (16 examples, yields 65-88%).
- Barbero,Degani,Diulgheroff,Dughera,Fochi
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p. 2180 - 2190
(2007/10/03)
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