- Synthesis of tri- and tetrasubstituted olefins by palladium cross-coupling reaction
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Tri- and tetrasubstituted olefins were obtained in high yields and regioselectivities using stilbene as starting material. First, stilbene was converted into (E)-bromostilbene by a bromination-dehydrobromination sequence. Then, (E)-bromostilbene was coupled with arylboronic acids at room temperature and low loading of Pd catalyst precursor (0.5-0.05 mol%) to afford selectively (E)-1-aryl-1,2-phenylethylenes in high yields (87-98%). Bromination of triphenylethylene afforded directly the bromotriphenylethylene that also underwent coupling reactions with arylboronic acids under mild conditions to afford tetrarylethylene (88-90% yield). Under the same conditions attempted Suzuki cross-coupling reactions of (E)-bromostilbene or 1,1,2-triphenylethene with alkylboronic acids were unsuccessful. However, the alkyl group could be introduced under mild conditions and high yields by using a Pd-catalyzed Negishi coupling protocol. Georg Thieme Verlag Stuttgart.
- Nunes, Carolina M.,Steffens, Daniela,Monteiro, Adriano L.
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Read Online
- Regio- and stereoselective synthesis of bromoalkenes by homolytic hydrobromination of alkynes with hydrogen bromide
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Homolytic hydrobromination of terminal and internal alkynes with a commercially available solution of hydrogen bromide in acetic acid has been investigated for regio- and stereoselective synthesis of bromoalkenes. Under an aerobic atmosphere at room temperature, the reaction of ethynylarenes with a small excess of HBr efficiently gave (2-bromoethenyl)arenes with good to high E-selectivity. (Alk-1-ynyl)arenes, or internal alkynes bearing both phenyl and alkyl groups at the sp-carbons also underwent the air-initiated hydrobromination to exhibit high Z-selectivity under kinetic conditions using a half equivalent of HBr.
- Kumaki, Wataru,Kinoshita, Hidenori,Miura, Katsukiyo
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- Visible light-mediated metal-free double bond deuteration of substituted phenylalkenes
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Various bromophenylalkenes were reductively photodebrominated by using 1,3-dimethyl-2-phenyl-1H-benzo-[d]imidazoline (DMBI) and 9,10-dicyanoanthracene. With deuterated DMBI analogs (the most effective was DMBI-d11), satisfactory to excellent isotopic yields were obtained. DMBI-d11 could also be regenerated from the reaction mixtures with a recovery rate of up to 50%. The combination of the photodebromination reaction with conventional methods for bromoalkene synthesis enables sequential monodeuteration of a double bond without the necessity of a metal catalyst. This journal is
- Iakovenko, Roman,Hlavá?, Jan
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supporting information
p. 440 - 446
(2021/01/28)
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- Regioselective Synthesis of α-Functional Stilbenes via Precise Control of Rapid cis- trans Isomerization in Flow
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The rapid cis-trans isomerization of α-anionic stilbene was regioselectively controlled by using flow microreactors, and its reaction with various electrophiles was conducted. The reaction time was precisely controlled within milliseconds to seconds at -50 °C to selectively give the cis- or trans-isomer in high yields. This synthetic method in flow was well-applied to synthesize precursors of commercial drug compound, (E)- and (Z)-tamoxifen with high regioselectivity and productivity.
- Lee, Hyune-Jea,Yonekura, Yuya,Kim, Nayoung,Yoshida, Jun-Ichi,Kim, Heejin
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supporting information
p. 2904 - 2910
(2021/05/05)
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- Iridium-Catalyzed Hydrochlorination and Hydrobromination of Alkynes by Shuttle Catalysis
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Described herein are two different methods for the synthesis of vinyl halides by a shuttle catalysis based iridium-catalyzed transfer hydrohalogenation of unactivated alkynes. The use of 4-chlorobutan-2-one or tert-butyl halide as donors of hydrogen halides allows this transformation in the absence of corrosive reagents, such as hydrogen halides or acid chlorides, thus largely improving the functional-group tolerance and safety profile of these reactions compared to the state-of-the-art. This method has granted access to alkenyl halide compounds containing acid-sensitive groups, such as tertiary alcohols, silyl ethers, and acetals. The synthetic value of those methodologies has been demonstrated by gram-scale synthesis where low catalyst loading was achieved.
- Yu, Peng,Bismuto, Alessandro,Morandi, Bill
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supporting information
p. 2904 - 2910
(2020/01/25)
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- TsNBr2 promoted decarboxylative bromination of α,β-unsaturated carboxylic acids
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A rapid process for decarboxylative bromination of α,β-unsaturated carboxylic acids have been developed using N,N-dibromo-p-toluenesulfonamide (TsNBr2). Treatment of cinnamic acids with TsNBr2 in presence of potassium carbonate in acetonitrile produces corresponding β-bromostyrenes at room temperature. Exclusive formation of (E)-β-bromostyrenes was observed in a stereoselective manner within a very short period of time (5–15 min). This method was further extended for obtaining 1-bromoalkynes from corresponding propiolic acids. Instantaneous formation of bromoalkynes was observed when the reaction was carried out in presence of DBU as a base in acetonitrile at room temperature. A wide variety of cinnamic acids and propiolic acids could be converted to corresponding β-bromostyrenes and 1-bromoalkynes respectively under mild reaction condition with high to excellent yield.
- Hazarika, Debojit,Phukan, Prodeep
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supporting information
p. 4593 - 4596
(2018/11/23)
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- Regioselective Synthesis of Vinyl Halides, Vinyl Sulfones, and Alkynes: A Tandem Intermolecular Nucleophilic and Electrophilic Vinylation of Tosylhydrazones
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A diazo species is trapped in an intermolecular fashion by two independent ion species in tandem at the carbene center to install an electrophile and a nucleophile on the same carbon. This metal-free concept, which is unprecedented, has been illustrated by regioselective synthesis of a variety of vinyl halides, vinyl sulfones, and alkyne derivatives. (Chemical Equation Presented).
- Ojha, Devi Prasan,Prabhu, Kandikere Ramaiah
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- Nucleophile-selective cross-coupling reactions with vinyl and alkynyl bromides on a dinucleophilic aromatic substrate
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A nucleophile-selective cross-coupling reaction on an aromatic compound bearing two metal groups, Bpin and SnMe3, has been developed. Previously, only aryl bromides and iodides could be used as electrophilic components, but in this work, the scope could be extended to vinyl and alkynyl bromides as electrophiles. This means that the roles typical in Sonogashira couplings or Heck reactions of the aromatic ring as the dielectrophile coupling to vinyl and alkynyl metal species are reversed, which presents a new tool for organic synthesis. The first nucleophilic site to react is the stannyl group, and subsequently, a Suzuki-Miyaura cross-coupling reaction can take place on the same molecule.
- He, Lu-Ying,Schulz-Senft, Mathias,Thiedemann, Birk,Linshoeft, Julian,Gates, Paul J.,Staubitz, Anne
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supporting information
p. 2498 - 2502
(2015/04/22)
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- The synthesis of 1,2-diarylindenes via DDQ-mediated dehydrogenative intramolecular cyclization
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A direct DDQ-mediated dehydrogenative intramolecular cyclization of (Z)-1,2,3-triaryl substituted propylenes promoted by Cu(OAc)2 was developed, providing 1,2-diarylindene derivatives in moderate to good yields (up to 92%) under mild conditions
- Li, Yi,Cao, Li,Luo, Xiaoyan,Deng, Wei-Ping
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p. 5974 - 5979
(2015/03/30)
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- A novel method for bromodecarboxylation of α,β-unsaturated carboxylic acids using catalytic sodium nitrite
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A first novel synthetic utility of catalytic sodium nitrite in combination with aqueous HBr, for bromo decarboxylation of α,β-unsaturated carboxylic acid is described. α,β-Unsaturated carboxylic acid compounds successfully converted into corresponding bromo compounds. The advantages of this protocol are shorter reaction time and moderate to good yields.
- Telvekar, Vikas N.,Takale, Balaram S.
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experimental part
p. 2394 - 2396
(2011/05/09)
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- Elucidation of the stereochemistry of thiirane formation from a 1λ4,2-dithietane bearing two chiral carbon centers
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A tetracoordinated sulfurane bearing a 1λ4,2-dithietane moiety, whose 3- and 4-positions were chiral carbon centers, was synthesized. Its thermolysis gave the corresponding thiirane as a single diastereomer, whose configuration and stereochemis
- Kusaka, Shinpei,Kano, Naokazu,Kawashima, Takayuki
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experimental part
p. 412 - 417
(2011/07/31)
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- Trans-stilbene as a starting material for the synthesis of tamoxifen based on palladium-catalyzed cross-coupling reactions
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(Z)-Tamoxifen was synthesized from a simple olefin (trans-stilbene) in 5 steps and 40% overall yield (Z/E = 74:26). The phenyl substituted group (4-Me2NCH2CH2OC6H4) was attached by a bromination-dehydrobromination-Suzuki reaction sequence. Subsequently, the ethyl group was attached to the triarylated olefin by a bromination-Negishi reaction sequence. Both the Suzuki and Negishi cross-coupling processes are stereospecific, and the stereo-selectivity depends only on the bromination-dehydrobromination reactions. (Z)-Tamoxifen was also obtained from trans-stilbene in only 3 steps by using Heck reaction-bromination- Negishi reaction sequence in 57% overall yield (Z/E = 65:35). Georg Thieme Verlag Stuttgart.
- Nunes, Carolina M.,Limberger, Jones,Poersch, Silvia,Seferin, Marcus,Monteiro, Adriano L.
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scheme or table
p. 2761 - 2765
(2010/01/21)
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- Sol-gel entrapped pyridinium hydrobromide perbromide as a recyclable bromination agent: Its application to a one-pot bromination and dehydrobromination process
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Silica sol-gel encaged pyridinium hydrobromide perbromide can be used for clean, odorless bromination of a variety of substrates, including alkenes, ketones, and arenes. The used heterogenized bromination reagent can be recharged with bromine and recycled. In the presence of sol-gel entrapped 1,5,7-triazabicyclo[4.4.0]dec-5-ene, dibromides are dehydrobrominated to give vinyl monobromides and/or alkynes. Encapsulation of the pyridinium derivative and the guanidine base within separate sol-gel matrices enables the use of both opposing reagents in one-pot reactions without their mutual destroying each other. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Levin, Yevgenia,Hamza, Khalil,Abu-Reziq, Raed,Blum, Jochanan
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p. 1396 - 1399
(2007/10/03)
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- Halodephosphorylation of α,β-unsaturated phosphonic acid monoesters
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Reaction of α,β-ethylenic and acetylenic phosphonic acid monoesters with (biscollidine)iodine(I) or (biscollidine)bromine(I) hexafluorophosphate led to α,β-unsaturated halides by, without precedent, dephosphorylation reactions.
- Lahrache, Hind,Robin, Sylvie,Rousseau, Gérard
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p. 1635 - 1637
(2007/10/03)
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- Catalytic Hunsdiecker reaction and one-pot catalytic Hunsdiecker-Heck strategy: Synthesis of α,β-unsaturated aromatic halides, α- (dihalomethyl)benzenemethanols, 5-aryl-2,4-pentadienoic acids, dienoates and dienamides
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The reaction of α,β-unsaturated aromatic (or heteroaromatic) carboxylic acids with N-halosuccinimides (1 equiv.) and catalytic tetrabutylammonium trifluoroacetate (0.2 equiv.) in dichloroethane results in facile halodecarboxylation affording the corresponding (E)-halides in good to excellent yields. A similar reaction, but with 2 equiv. of N-halosuccinimides in acetonitrile-water (1:1 v/v) results in the exclusive formation of the corresponding α-(dihalomethyl)benzenemethanols. Furthermore, a one-pot strategy has been developed combining catalytic Hunsdiecker reaction (using tetrabutylammonium trifluoroacetate in dichloroethane) and Heck coupling (using palladium acetate/triethylamine/triphenylantimony/dichloroethane) for the synthesis of 5-aryl-2,4-pentadienoic acids, esters and amides in moderate to good yields. The natural product piperine and pipergualamine has been synthesized via the above route. Mechanistic and theoretical studies (via AM1 calculations) provide a useful insight into the mechanism of the present halodecarboxylation reaction, suggesting an ionic pathway involving the attack of the halogenium ion across the carbon-carbon double bond, triggering the elimination of carbon dioxide. (C) 2000 Elsevier Science Ltd.
- Naskar, Dinabandhu,Roy, Sujit
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p. 1369 - 1377
(2007/10/03)
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- 4-endo-trig cyclization processes using bis(collidine)bromine(i) hexafluorophosphate as reagent: Preparation of 2-oxetanones, 2-azetidinones, and oxetanes
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Reaction in methylene chloride of bis(collidine)bromine(I) hexafluorophosphate with α,β-unsaturated acids and α,β-unsaturated N- sulfonamides was found to lead diastereospecifically to the corresponding 2- oxetanones and 2-azetidinones in moderate yields (23-60%), by an almost unknown 4-endo cyclization. This process allow the synthesis of these interesting classes of products in one step from common substrates. Similarly, the reaction of cinnamic alcohols led, by the same cyclization procedure, to oxetanes (20-36%); the presence of a gem-dimethyl group in α of the alcohol function appeared beneficial.
- Homsi, Fadi,Rousseau, Gerard
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- An easy access to trisubstituted vinyl chlorides and improved synthesis of chloro/bromostilbenes
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The α-chlorophosphonates (OCH2CMe2CH2O)P(O)CHCl-C6H4-4-R [R=H (4), Me (5), OMe (6)], which are now readily accessible, react with ketones R'C(O)R' in the presence of NaH (without recourse to the more expensive t- BuLi) to afford trisubstituted vinyl halides R'C(R')=CCl(C6H4-4-R) in good yields. The corresponding α-bromophosphonates [R=H (7), Me (8)] failed to react with ketones and gave the symmetrical acetylenes 4-R-C6H4-C=C- C6H44-R as isolable products in low yield. We have found that K2CO3 in refluxing xylene is a good base for the synthesis of chlorostilbenes; using this base the bromostilbenes ArCH=CBr(C6H44-R) can be prepared in significantly higher yields than by using NaH. The stereochemistry of two of the trisubstituted vinyl chlorides is unambiguously proven by X-ray structure determination. Thus for (Cl)PhC=CPh(Me), the isomer with the upfield NMR shift for the CH3 protons and for (Cl)PhC=C(Ph)(C6H4-4-Me), the isomer with the downfield NMR shift for the -C6H4-4-CH3 protons have Z stereochemistry.
- Muthiah,Kumar, K. Praveen,Kumaraswamy, Sudha,Kumara Swamy
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p. 14315 - 14326
(2007/10/03)
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- Is metal necessary in the Hunsdiecker-Borodin reaction?
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The tetrabutylammonium trifluoroacetate (TBATFA) catalyzed conversion of α,β-unsaturated carboxylic acids to the corresponding halides with N-halosuccinimides in dichloroethane is reported as the first example of a metal-free catalytic version of the title reaction. The methodology was further employed for a facile synthesis of piperine.
- Naskar, Dinabandhu,Chowdhury, Shantanu,Roy, Sujit
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p. 699 - 702
(2007/10/03)
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- Rhodium-catalyzed reaction of aroyl chlorides with alkynes
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Aroyl chlorides react with terminal alkynes accompanied by decarbonylation in the presence of a catalytic amount of [RhCl(cod)]2 and PPh3 to give the corresponding vinyl chloride derivatives regioand stereoselectively in good yields.
- Kokubo, Ken,Matsumasa, Kenji,Miura, Masahiro,Nomura, Masakatsu
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p. 6941 - 6946
(2007/10/03)
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- Reactions of Stilbene Dibromides with 2-Nitropropan-2-yl Anion in DMSO. A Competing Ionic and SET Mechanism
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Reaction of dl- and meso-stilbene dibromides with 2-nitropropan-2-yl anion in DMSO proceed by the E2 mechanism, whereas that of erythro-p-nitrostilbene dibromide proceeds by a completing ionic and SET mechanism.
- Cho, Bong Rae,Lee, Eun Kyung,Kim, Hyun Soo
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p. 5801 - 5804
(2007/10/02)
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- Electronic and Conformational Effects in the Photochemistry of α-Alkenyl-Substituted Vinyl Halides
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The photochemical reactions in methanol of the vinylic halides 2-halo-1-phenyl-1,3-butadienes 1-3Z-X (β-halo-β-alkenylstyrenes) and 1-halo-1,2-diphenylethenes 4Z-X (α-halostilbenes), with X = Cl or Br, have been studied quantitatively.E/Z isomerization, dehydrohalogenation, nucleophilic substitution, a -halogen shift, a -hydrogen shift, and oxidation are observed as the primary reactions.No reductive dehalogenation products are formed.The efficiencies of product formation are dependent on the halogen used, the electron-donating capacity of the α-substituent, the ground state conformation of the starting material, and the wavelength of excitation.Apart from the photoinduced E/Z isomerization and the oxidation reaction typical for alkenes, product formation occurs exclusively via vinyl-cationic intermediates, which are formed upon photolytic cleavage of the carbon-halogen bond.These ionic species, or part of them, are present as vinyl cation/halide anion-pairs.
- Krijnen, Erik S.,Zuilhof, Han,Lodder, Gerrit
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p. 8139 - 8150
(2007/10/02)
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- Surface-Mediated Reactions. 4. Hydrohalogenation of Alkynes
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The use of appropriately prepared silica gel and alumina has been found to mediate the addition of hydrogen halides to alkynes.The technique has been rendered even more convenient by the use of various organic and inorganic acid halides that react in the presence of silica gel or alumina to generate hydrogen halides in situ.Treatment in this fashion of 1-propynylbenzene (1), which underwent no reaction in CH2Cl2 solution saturated with HCl, readily afforded the syn addition product, alkenyl chloride (E)-4a.On extended treatment (E)-4a underwent subsequent iaomerization to the thermodynamically more stable Z isomer.Thus either isomer of 4a could be obtained in good yield depending on the reaction conditions.In a similar way bromides (E)- and (Z)-4b were obtained without competing formation of the radical products (E)- and (Z)-5, which occurred in solution.In contrast with solution-phase hydroiodination of alkyne 1, which slowly afforded iodide (E)-4c, surface-mediated addition readily afforded (E)-4c, followed by isomerization to the Z isomer.E ->/- Z equilibration of the alkenyl halides 4 was shown to involve, at last in part, addition-elimination via the gem-dihalides 13.Analogous behavior was exhibited by the phenylalkynes 2 and 3 on surface-mediated hydrohalogenation.Surface-mediated addition of HBr and HI to the internal alkylalkyne 14 afforded principally the anti addition products (Z)-15b,c.Treatment of the terminal alkynes 17 and 22 with (COBr)2 over alumina gave the dibromides 20 and 24/25, respectively, whereas use of acetyl bromide as the HBr precursor afforded the alkenyl bromides 18b and 23.
- Kropp, Paul J.,Crawford, Scott D.
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p. 3102 - 3112
(2007/10/02)
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- Oxidative Halo-Decarboxylation of α,β-Unsaturated Carboxylic Acids
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A procedure for oxidative halo-decarboxylation of α,β-unsaturated carboxylic acids using iodosylbenzene, or iodosylbenzene diacetate, and N-chloro-, N-bromo-, or N-iodosuccinimide is presented.Good yields of the corresponding bromoalkenes are obtained when the α,β-unsaturated carboxylic acids are substituted with an aromatic substituent in the β-position and N-bromosuccinimide is used as the halogenation reagent.The scope of mainly the oxidative bromo-decarboxylation reaction is presented, and a tentative mechanism is proposed.
- Graven, Anette,Joergensen, Karl Anker,Dahl, Soeren,Stanczak, Andrzej
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p. 3543 - 3546
(2007/10/02)
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- Debromination of meso- and (+/-)-1,2-Dibromo-1,2-diphenylethane by 9-Substituted Fluorenide Ions. Correlation between Stereochemical Results and Redox Potentials
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The ratio between (E)- and (Z)-1,2-diphenylethene, (E:Z), has been obtained for the reaction of ten 9-substituted fluorenide ions with 1,2-dibromo-1,2-diphenylethane in dimethyl sulfoxide.It has been demonstrated that both the redox potential of the fluorenide anion and the bulkiness of the 9-substituent are important parameters in the interpretation of the observed variation (0.08-1.64) of the E:Z ratio.
- Lund, Torben,Bjoern, Christian,Hansen, Helle S.,Jensen, Anne K.,Thorsen, Teddy K.
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p. 877 - 884
(2007/10/02)
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- Conversion of Stilbene to trisubstituted Olefins
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Determination of stereochemistry of bromination-dehydrobromination of both cis and trans-stilbene has been achieved.Coupling of the resulting vinyl bromides with alkyl or aryl groups have been done.The coupling products could serve as intermediates for the synthesis of biologically active tetrasubstituted olefins.
- Al-Hassan, Mohammed I.
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p. 463 - 472
(2007/10/02)
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- Indirect Electrochemical Reduction of Vinyl Halides and Related Compounds
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Some substituted vinyl halides and related compounds have been reduced indirectly by electrolysis using anion radicals as mediators.The rate of electron transfer from the electron donors to the electron acceptors has been measured by cyclic voltammetry, and the solvent and bond reorganization energy, λ, has been extracted from the data using the Marcus equation.The λ values for the vinyl and cyclopropyl halides were found to be closer to those for aryl halides than those for alkyl halides.The method was used preparatively for selective dehalogenation of vinyl halides, including derivatives of 10-bromo-5H-dibenzazepine.
- Gatti, Norberto,Jugelt, Werner,Lund, Henning
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p. 646 - 652
(2007/10/02)
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- Elimination Reactions of Stilbene Dibromides. Debromination by Cyanide, Chloride, Iodide or 4-Nitrothiophenoxide Ions in Dimethylformamide
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Transition state structures for debromination reactions of a series of para-substituted stilbene dibromides were evaluated from kinetic and product distribution data for the nucleophiles chloride, cyanide, iodide and 4-nitrothiophenoxide in dimethylformamide.The debrominations appear to utilize transition states in which nucleophilic attack is at bromine despite the strong carbon-nucleophilicity of some of the bases.Products are largely those derived from anti-debromination with all nucleophiles and reactivity is in the order 4-nitrothiophenoxide > cyanide >iodide > chloride.
- Avraamides, James
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p. 677 - 686
(2007/10/02)
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- Hydroxide Ion Initiated Reactions under Phase Transfer Catalysis Conditions. 9. Dehydrohalogenation of (Haloethyl)benzenes by Quaternary Ammonium Salts
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Elimination of HCl and HBr from (1- and (2-haloethyl)benzenes in the presence of aqueous sodium hydroxide and quaternary ammonium salts which cannot extract hydroxide anion to the organic phase is shown to proceed via a reverse phase transfer process.The catalyst QX promotes the elimination and forms QX-HX adduct which is neutralized at the interphase by the hydroxide base.First-order kinetics is observed under conditions in which the catalyst is stable.Complicated kinetics is obtained when decomposition of the catalyst takes place simultaneously with the reaction.
- Halpern, Marc,Zahalka, Hayder A.,Sasson, Yoel,Rabinovitz, Mordecai
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p. 5088 - 5092
(2007/10/02)
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- NAD(P)+-NAD(P)H Model. 54. Free Radical Mechanism for the Reductive Debromination of vic-Dibromides to Alkenes
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vic-Dibromides undergo reductive debromination with a model of NAD(P)H, N-benzyl-1,4-dihydronicotinamide, to afford the corresponding alkenes quantitatively.Stereochemistry of the reduction suggests that the reaction involves a free radical intermediacy.
- Yasui, Shinro,Nakamura, Kaoru,Ohno, Atsuyoshi
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p. 1847 - 1848
(2007/10/02)
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- Elimination Reactions of Stilbene Dibromides. Dehydrobromination by Acetate, Cyanide or Chloride Ions in Dimethylformamide
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Rates of dehydrobromination of a series of 4-nitro- and methoxystilbene dibromides by means of acetate, cyanide or chloride ions in dimethylformamide have been measured.A product analysis was performed which indicated a strong preference for anti elimination.Probable transition state structures utilized by each of the three nucleophiles are described.Attack by the base may be at either β-hydrogen (E 2H) or Cα(E2C).The slowest reaction in with chloride ion, which also gives the highest anti/syn elimination product ratio.
- Avraamides, James,Parker, Alan J.
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p. 1705 - 1717
(2007/10/02)
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