- Synthesis of tetrasubstituted olefins by Pd-catalyzed addition of arylboronic acids to internal alkynes
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(Chemical Equation Presented) Tetrasubstituted olefins are readily prepared by the Pd-catalyzed cis addition of two aryl groups from an arylboronic acid to opposite ends of the triple bond of internal alkynes. The synthesis proceeds under very mild reaction conditions and tolerates a wide variety of functional groups, including alcohol, aldehyde, ester, TMS, and acetal groups.
- Zhou, Chengxiang,Larock, Richard C.
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- Molecular mechanism of action of 2-ferrocenyl-1,1-diphenylbut-1-ene on hl-60 leukemia cells
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The aim of this work was to investigate the mechanism of action of 2-ferrocenyl-1,1-diphenylbut-1-ene (1) on HL-60 human leukemia cells. While inactive against noncancerous cells, 1 provoked a concentration-dependent decrease in viable tumor cells, primarily via apoptosis, as evidenced by analysis of cell morphology, activation of caspases 3 and 7, increased DNA fragmentation, and externalization of phosphatidylserine. Necrosis was observed only at the highest tested concentration (4 μM). Compound 1 interfered with the cell cycle, causing an accumulation of cells in the G1/G0 phase. Interaction of 1 with dsDNA and ssDNA was observed by differential pulse voltammetry and confirmed by hyperchromicity in the UV/Vis spectra of dsDNA, with an interaction constant of 2×104 M-1. Both the organic analogue 1,1,2-triphenylbut-1-ene (2) and ferrocene were inactive against cancer and noncancer cell lines and did not react with DNA. These results reinforce the idea that the hybrid strategy of conjugating ferrocene to the structure of tamoxifen derivatives is advantageous in finding new substances with antineoplastic activity.
- De Oliveira, Alane Cabral,Da Silva, Emanuella Gomes,Rocha, Danilo Damasceno,Hillard, Elizabeth A.,Pigeon, Pascal,Jaouen, Gérard,Rodrigues, Felipe A. R.,De Abreu, Fabiane C.,Da Rocha Ferreira, Fabrícia,Goulart, Marilia O. F.,Costa-Lotufo, Letícia V.
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- Asymmetric Hydrogenation of Unfunctionalized Tetrasubstituted Acyclic Olefins
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Asymmetric hydrogenation has evolved as one of the most powerful tools to construct stereocenters. However, the asymmetric hydrogenation of unfunctionalized tetrasubstituted acyclic olefins remains the pinnacle of asymmetric synthesis and an unsolved challenge. We report herein the discovery of an iridium catalyst for the first, generally applicable, highly enantio- and diastereoselective hydrogenation of such olefins and the mechanistic insights of the reaction. The power of this chemistry is demonstrated by the successful hydrogenation of a wide variety of electronically and sterically diverse olefins in excellent yield and high enantio- and diastereoselectivity.
- Bachmann, Stephan,Bigler, Raphael,Denmark, Scott E.,Gosselin, Francis,Han, Chong,Hildbrand, Stefan,Mack, Kyle A.,Pfaltz, Andreas,Scalone, Michelangelo,Shen, Jeff,Tosatti, Paolo,Zhang, Haiming
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supporting information
p. 2844 - 2849
(2020/02/05)
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- Iterative synthesis of alkenes by insertion of lithiated epoxides into boronic esters
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The insertion of lithiated epoxides into boronic esters followed by thermal syn-elimination provides a stereospecific entry to alkenes. This process avoids transition metals and is amenable to iteration to provide higher substitution patterns.
- Bojaryn, Kevin,Fritsch, Stefan,Hirschhaüser, Christoph
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supporting information
p. 2218 - 2222
(2019/04/10)
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- SnCl4-Zn: A novel reductive system for deoxygenative coupling of aliphatic, aromatic, chalcone epoxide, and indanone carbonyl compounds to olefins
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SnCl4-Zn complex provided a novel reductive system in the deoxygenative cross-coupling of aliphatic, aromatic, chalcone epoxide and indanone carbonyl compounds to olefins in high yield (55-86%) at reflux temperature in THF. The advantage of this reagent is inexpensive, short reaction time, and high yield compared to the reagents used in the McMurry cross-coupling reaction.
- Pathe, Gulab Khushalrao,Ahmed, Naseem
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supporting information
p. 1555 - 1561
(2015/03/14)
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- Molecular Mechanism of Action of 2-Ferrocenyl-1,1-diphenylbut-1-ene on HL-60 Leukemia Cells
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The aim of this work was to investigate the mechanism of action of 2-ferrocenyl-1,1-diphenylbut-1-ene (1) on HL-60 human leukemia cells. While inactive against noncancerous cells, 1 provoked a concentration-dependent decrease in viable tumor cells, primarily via apoptosis, as evidenced by analysis of cell morphology, activation of caspases 3 and 7, increased DNA fragmentation, and externalization of phosphatidylserine. Necrosis was observed only at the highest tested concentration (4 μM). Compound 1 interfered with the cell cycle, causing an accumulation of cells in the G1/G0 phase. Interaction of 1 with dsDNA and ssDNA was observed by differential pulse voltammetry and confirmed by hyperchromicity in the UV/Vis spectra of dsDNA, with an interaction constant of 2×104M-1. Both the organic analogue 1,1,2-triphenylbut-1-ene (2) and ferrocene were inactive against cancer and noncancer cell lines and did not react with DNA. These results reinforce the idea that the hybrid strategy of conjugating ferrocene to the structure of tamoxifen derivatives is advantageous in finding new substances with antineoplastic activity.
- De Oliveira, Alane Cabral,Da Silva, Emanuella Gomes,Rocha, Danilo Damasceno,Hillard, Elizabeth A.,Pigeon, Pascal,Jaouen, Grard,Rodrigues, Felipe A. R.,De Abreu, Fabiane C.,Da Rocha Ferreira, Fabrcia,Goulart, Marilia O. F.,Costa-Lotufo, Letcia V.
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p. 2580 - 2586
(2015/08/24)
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- Oxidative heck arylation for the stereoselective synthesis of tetrasubstituted olefins using nitroxides as oxidants
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One, two, and three! Nitroxides and dioxygen serve as oxidants in highly stereoselective oxidative Pd-catalyzed Heck arylations in which aryl boronic acids are used to synthesize triarylalkyl-substituted olefins. The reactions occur under very mild conditions at room temperature. As an example, the threefold sequential arylation of methyl acrylate is the crucial step in the stereoselective synthesis of Z-Tamoxifen.
- He, Zhiheng,Kirchberg, Sylvia,Froehlich, Roland,Studer, Armido
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p. 3699 - 3702
(2012/05/20)
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- 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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p. 103 - 106
(2008/03/13)
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- Tetrasubstituted olefin synthesis via Pd-catalyzed addition of arylboronic acids to internal alkynes using O2 as an oxidant
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The Pd(II)-catalyzed reaction of arylboronic acids and internal alkynes provides a convenient route to a wide variety of tetrasubstituted olefins. The reaction is conducted in DMSO using molecular O2 as an oxidant in the absence of any base. The reaction involves the cis addition of two aryl groups from the arylboronic acid to opposite ends of the triple bond of the internal alkyne. The synthesis tolerates a wide variety of functional groups, including alcohol, aldehyde, ester, TMS, and acetal groups. Electron-rich dialkylacetylenes, such as 4-octyne, provide highly substituted 1,3-dienes in moderate yields. The very mild O2/DMSO conditions also afford good to excellent yields of biaryls by the homocoupling of arylboronic acids.
- Zhou, Chengxiang,Larock, Richard C.
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p. 3184 - 3191
(2007/10/03)
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- Facile synthesis of multisubstituted buta-1,3-dienes via Suzuki-Miyaura and Kumada cross-coupling strategy of 2,4-diiodo-buta-1-enes with arylboronic acids and Grignard reagents
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One-pot Suzuki-Miyaura-type and Kumada-type cross-coupling reactions of 2,4-diiodo-buta-l-enes with arylboronic acids and alkyl/aryl magnesium bromides were carried out in the presence of accessibly simple catalysts under mild conditions. As a result, some 1,1,2-trisubstituted buta-1,3-dienes were obtained including the Tamoxifen-type, which have potential adjuvant therapy in women who have suffered from breast cancer and cyclooxygenase-2-type (COX-2-type) inhibitors, some of which have been proved to elicit efficient anti-inflammatory analgesic activities and less adverse gastrointestinal side effects and to be very useful in the prophylactic treatment of a wide variety of cancers and neurodegenerative disorders. The Royal Society of Chemistry 2005.
- Shao, Li-Xiong,Shi, Min
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p. 1828 - 1831
(2007/10/03)
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- N-alkoxypyrazoles as biomimetics for the alkoxyphenyl group in tamoxifen
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The preparation of a series of novel analogues of the selective antiestrogen tamoxifen is reported. 1Z-alkoxyphenyl group in tamoxifen has been replaced by a N-alkoxypyrazole, while functionalised phenyl groups or heteroaromatics were introduced at the 2Z
- Wenckens, Martin,Jakobsen, Palle,Vedso, Per,Huusfeldt, Per Olaf,Gissel, Birgitte,Barfoed, Marianne,Brockdorff, Bettina Lundin,Lykkesfeldt, Anne E.,Begtrup, Mikael
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p. 1883 - 1899
(2007/10/03)
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- Regioselective Metallation of Propylbenzene with Superbase: A Convenient Route to Stilbene Derivatives
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The benzylic metallation of propylbenzene has been elaborated with LIC-KOR superbase; the method has been applied in a new synthesis of stilbene derivatives.
- Thurner, Angelika,Agai, Bela,Faigl, Ferenc
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p. 158 - 159
(2007/10/03)
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- Monophenylation accompanied by partial reduction of 1,1-dihalogeno-2-phenyl-1-alkenes in the presence of a nickel-phosphine complex
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Reaction of 1,1-dihalogeno-2-phenyl-1-alkenes (I) with phenylmagnesium bromide in the presence of NiCl2(dppp) in THF has been studied.Mono-cross-coupling accompanied by partial reduction gave (E)-1,2-diphenyl-1-alkenes (III) as the major products.Use of a large excess of Grignard reagent increased the yields of III and the (Z)-isomers (II), with a decrease in the yield of double cross-coupling products, 1,1,2-triphenyl-1-alkenes (IV).The highest ratio of the sum of the yields of the monophenylation products to the yield of the double cross-coupling product, (II+III)/IV=36.5, was found for the reaction of PhMgBr with 1,1-dibromo-2-phenylpropene (Ib) in a 12.0/1 molar ratio.A possible reaction mechanism is described.
- Okamoto, Yuzo,Yoshikawa, Yutaka,Hayashi, Takatoshi
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p. 143 - 150
(2007/10/02)
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- 1,1,2-Triphenylbut-1-enes: Relationship between Structure, Estradiol Receptor Affinity, and Mammary Tumor Inhibiting Properties
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1,1,2-Triphenylbut-1-enes, which are substituted with acetoxy groups on one, two, or three aromatic rings in the para and/or meta positions, were synthesized.The identity of the occurring E and Z isomers were established by 1H NMR spectroscopy.A study on structure-activity relationships was carried out with regard to estradiol receptor affinity and to inhibiting effects on the growth of a postmenopausal human mammary carcinoma implanted in nude mice.The para-substituted compounds generally exhibited a higher receptor affinity and a better antitumor activity than the corresponding meta-substituted ones.The E isomers were superior to the respective Z isomers in those two properties.The tumor-inhibiting effect of the mono-and disubstituted compounds was better than that of the trisubstituted ones.Except for the trisubstituted compounds, they all showed a good correlation between estradiol receptor affinity and antitumor activity.One of the compounds was also tested on the 9,10-dimethylbenzanthracene-induced, hormone-dependent mammary carcinoma of the Spraque-Dawley rat, and the results corresponded to those obtained in the xenograft tumor.
- Schneider, Martin R.,Angerer, Erwin von,Schoenenberger, Helmut,Michel, Ralf Th.,Fortmeyer, H. P.
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p. 1070 - 1077
(2007/10/02)
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