- Palladium-Catalyzed Two-Component Domino Coupling Reaction of (Z)-β-Bromostyrenes with Norbornenes: Synthesis of 1,5-Enynes
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Polyfunctional molecules, 1,5-enynes, have been achieved via a palladium(0)-catalyzed domino coupling reaction of (Z)-β-bromostyrenes with norbornenes in the presence of cesium carbonate and N,N-dimethylformamide. The process involves a double Heck-type procedure, two-fold C(sp2) H activation and formation of two carbon-carbon bonds. There are possibilities of diversified transformation for the domino coupling of (Z)-β-bromostyrenes with norbornenes, the procedure is successfully driven to 1,5-enynes via accurate adjustment of the reaction conditions. (Figure presented.) .
- Mao, Jiangang,Li, Huifang,Wen, Herui,Li, Min,Fan, Xiaolin,Bao, Weiliang
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Read Online
- Method for synthesizing alpha,beta-dibromide
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The invention discloses a method for synthesizing alpha,beta-dibromide. The method is characterized in that a styrene compound as shown in the formula I is taken as a raw material, Zn-Al hydrotalciteZnAl-BrO3-LDHs of a bromate intercalation is taken as
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Paragraph 0056; 0057; 0058
(2018/04/01)
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- A Facile Access to trans -3-Styryl-4-hydrazinocyclopentenes via Palladium-Catalyzed Ring Opening of Diazanorbornenes with (Z)-β-Bromostyrenes/2,3-Dibromohydrocinnamic Acids
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trans -3-Styryl-4-hydrazinocyclopentenes have been synthesized via palladium-catalyzed desymmetrization of diazanorbornenes with (Z)-β-bromostyrenes. The reaction also works well with (Z)-β-bromostyrenes generated in situ from 2,3-dibromohydrocinnamic acids. The synthesized hydrazinocyclopentenes provide an easy route towards synthetic intermediates of many scaffolds of biological potential.
- Saranya,Chand, S. Sarath,Gopalan, Greeshma,Jijitha,Radhakrishnan
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p. 184 - 192
(2017/10/13)
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- Carbene-catalyzed LUMO activation of alkyne esters for access to functional pyridines
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A carbene-catalyzed LUMO activation of α,β-unsaturated alkyne esters is reported. This catalytic process allows for effective reactions of alkyne esters with enamides to synthesize functional pyridines via simple protocols. A previously unexplored unsaturated alkyne acyl azolium intermediate is involved in the key step of the reaction.
- Mou, Chengli,Wu, Jichang,Huang, Zhijian,Sun, Jun,Jin, Zhichao,Chi, Yonggui Robin
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supporting information
p. 13359 - 13362
(2017/12/26)
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- Palladium(0)-Catalyzed Methylcyclopropanation of Norbornenes with Vinyl Bromides and Mechanism Study
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An unusual methylcyclopropanation from [2 + 1] cycloadditions of vinyl bromides to norbornenes catalyzed by Pd(OAc)2/PPh3 in the presence of CH3ONa and CH3OH has been established. A methylcyclopropane subunit was installed by a 3-fold domino procedure involving a key protonation course. Preliminary deuterium-labeling studies revealed that the proton came from methyl of CH3OH and also exposed an additional hydrogen/deuterium exchange process. These two proton-concerned reactions were fully chemoselective.
- Mao, Jiangang,Xie, Hujun,Bao, Weiliang
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supporting information
p. 3678 - 3681
(2015/08/18)
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- Palladium(0)-catalyzed methylenecyclopropanation of norbornenes with vinyl bromides
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Highly strained methylenecyclopropane derivatives have been achieved via a novel and efficient Pd(0)-catalyzed domino reaction. The formal [2 + 1] cycloaddition reaction of vinyl bromides to norbornenes involves a Heck-type coupling and a C(sp2)-H bond activation.
- Mao, Jiangang,Bao, Weiliang
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supporting information
p. 2646 - 2649
(2014/06/09)
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- Palladium-catalyzed [2+1+1] annulation of norbornenes with (z)-bromostyrenes: Synthesis of bismethylenecyclobutanes via twofold C(sp2)-H bond activation
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The first Pd-catalyzed intermolecular [2+1+1] annulation reaction of (Z)-bromostyrene derivatives and norbornenes has been realized. Bismethylenecyclobutane derivatives were obtained with high yields. The domino coupling reaction involves a double Heck-type coupling process, twofold C(sp2)-H bond activation and formation of three carbon-carbon bonds.
- Mao, Jiangang,Bao, Weiliang
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supporting information
p. 15726 - 15729
(2015/01/08)
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- Convenient synthesis of terminal alkynes from anti-3-aryl-2,3- dibromopropanoic acids using a K2CO3/DMSO system
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A convenient, efficient, and generally applicable method was developed for the synthesis of terminal alkynes from anti-3-aryl-2,3-dibromopropanoic acids in the presence of DMSO and K2CO3.
- Cheng, Xuezhi,Jia, Jun,Kuang, Chunxiang
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experimental part
p. 2350 - 2354
(2012/02/03)
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- Synthesis of (Z)-1-bromo-1-alkenes and terminal alkynes from anti-2,3-dibromoalkanoic acids by microwave-induced reaction
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(Z)-1-Bromo-1-alkenes were stereoselectively prepared in high yields in a short reaction time by microwave irradiation of the corresponding anti-2,3-dibromoalkanoic acids in a Et3N/DMF system. A one-pot synthesis of terminal alkynes and enynes from 2,3-dibromoalkanoic acids were also developed by microwave-induced reaction.
- Kuang, Chunxiang,Yang, Qing,Senboku, Hisanori,Tokuda, Masao
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p. 4043 - 4052
(2007/10/03)
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- Convenient and stereoselective synthesis of (Z)-1-bromo-1-alkenes by microwave-induced reaction
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(Z)-1-Bromo-1-alkenes were stereoselectively prepared in high yields in a short reaction time (0.2-1.0 min) by microwave irradiation of the corresponding 2,3-dibromoalkanoic acids in DMF in the presence of triethylamine.
- Kuang, Chunxiang,Senboku, Hisanori,Tokuda, Masao
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p. 3893 - 3896
(2007/10/03)
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- A mild procedure for the stereospecific transformation of trans cinnamic acid derivatives to cis β-bromostyrenes
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A new mild procedure has been developed for the synthesis of cis β- bromostyrene analogs with complete Z/E selectivity and good to excellent yields (58.4 - 90.9 %). The process involves carboxyl-halo-elimination of cinnamic acid dibromides by using triethylamine in N,N-dimethylformamide at room temperature. A one-pot procedure has also been described for the direct transformation of cinnamic acids to β-bromostyrenes.
- Kim, Sun Hee,Wei, Han-Xun,Willis, Steven,Li, Guigen
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p. 4179 - 4185
(2007/10/03)
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- Synthesis of the Substituted Z-1-Bromo-1-alkenes and Arylacetylenes from 2,3-Dibromocarboxylic Acids
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Stereoselectivity was studied of simultaneous debromination-decarboxylation of dibrominated cinnamic and acrylic acids. The best selectivity in formation of Z-vinyl bromides was achieved with the use of organic nitrogen bases. The 1-bromo-1-alkenes were converted into the corresponding acetylenes.
- Matveeva,Erin,Kurz
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p. 1065 - 1067
(2007/10/03)
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- Iodide-induced Debromination of Cinnamic Acid and Substituted Cinnamic Acid Dibromides in 2-Methoxyethanol
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The second order rate constants for the iodide-induced debromination of cinnamic acid and substituted cinnamic acid dibromides in 2-methoxyethanol are reported; the reactivities follow the order: p-OCH3 > o-CH3 > p-CH3 > p-NO2 > p-Cl > m-NO2 > -H > m-CH3 > m-OCH3 > o-Cl.The m-CH3 and p-Cl derivatives have higher enthalpies and lower negative entropies of activation whereas methoxy substituted derivatives are characterised by lower enthalpies and higher negative entropies of activation than the unsubstituted acid.The free energy of activation is nearly constant.
- Subramanian, K.,Mathai, I. M.
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p. 909 - 911
(2007/10/02)
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- Synthesis of 3-Arylcoumarins, Thiacoumarins and Carbostyrils
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3-Arylcarbostyrils (2a-f), coumarins (2g-j) and thiacoumarin (2k) have been prepared by a generalised method from α,β-dibromohydrocinnamoyl derivatives (1a-k).The intermediate dihydrocoumarins and dihydrocarbostyrils (3, Y = O, NH) have been prepared which on acid treatment furnish 2.However, treatment of 3 with a base affords the 4-arylcoumarins and carbostyrils (4).
- Natarajan, M.,Manimaran, T.,Ramakrishnan, V. T.
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p. 529 - 534
(2007/10/02)
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- A CONVENIENT METHOD FOR THE CONVERSION OF trans to cis-CINNAMIC ACIDS
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trans-Cinnamic acids react in sequence with bromine, base, and carbon monoxide to give cis-acids in reasonable yields.
- Galamb, Vilmos,Alper, Howard
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p. 2965 - 2968
(2007/10/02)
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- Silanes in Organic Synthesis. 8. Preparation of Vinylsilanes from Ketones and Their Regiospecific Cyclopentenone Annulation
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A general method is described for the formation of vinylsilanes from ketones.Thus, conversion to the benzene- or p-toluenesulfonylhydrazone and sequential treatment with n-butyllithium and chlorotrimethylsilane in anhydrous tetramethylethylenediamine proceeds regiospecifically to afford the less substituted vinylsilane (in unsymmetrical cases).Friedel-Crafts acylation with acryloyl chlorides and aluminium chloride and subsequent Nazarov cyclization with Lewis acid catalysis results in cyclopentenone annulation.Numerous examples that reveal the scope of this processare described.Due to accompanying polymerization, annulation with acryloyl chloride itself is least efficient.This complication can, however, be averted through use of β-chloropropionyl chloride and dehydrochlorination with 1,5-diazabicycloundec-5-ene prior to ring closure.
- Paquette, Leo A.,Fristad, William E.,Dime, David S.,Bailey, Thomas R.
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p. 3017 - 3028
(2007/10/02)
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