- Unexpected reactions of simple iron alkyls with a thiosulfinate ester capable of serving as a disulfur monoxide source
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Attempts to use 4,5-diphenyl-3,6-dihydro-1,2-dithiin-1-oxide as a disulfur monoxide (S2O) source for S2O insertion into the metal carbon bond of CpMenFe(CO)2R (n = 0, 5; R = Me, Et) yielded unexpected iron thioester complexes, CpMenFe(CO)2SC(O)R.The characterization and independent syntheses of these thioester complexes are reported as well as the results of experiments designed to yield some information about the mechanism of formation of these thioester complexes.
- Powell, Kimberly R.,Elias, W. Jeff,Welker, Mark E.
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- Novel synthesis of 2,3-bisboryl-1,3-dienes from 1-bromo-1-lithioethene and 1,1-bisborylalkenes
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Treatment of 1,1-[bis(pinacolato)bory1]alkenes with excess of 1-bromo-1-lithioethene was found to give 2,3-bis[(pinacolato)bory1]-1,3-dienes in moderate to good yields. Synthetic applications of 2,3-[bis(pinacolato)bory1]-1,3-butadiene were also demonstrated.
- Shimizu,Kurahashi,Hiyama
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- Solid Acid-Catalyzed Dehydration of Pinacol Derivatives in Ionic Liquid: Simple and Efficient Access to Branched 1,3-Dienes
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The selective dehydration of pinacol derivatives to branched 1,3-dienes is extremely challenging because of the predominance of pinacol rearrangement. Herein, we successfully achieve this goal by employing a recyclable solid acid/ionic liquid catalyst system. The dehydration of alkyl- and cycloalkyl-derived diols in an Amberlyst-15/[Emim]Cl system afforded the corresponding 1,3-dienes in good yields, while a Nafion/[Emim]Cl system was demonstrated to be a better catalyst system for the dehydration of aryl-substituted substrates. Our protocol features straightforward and simple access to branched 1,3-dienes, high chemoselectivity, a recyclable catalyst system, a facile separation of dienes just by decantation, and a broad substrate scope.
- Hu, Yancheng,Li, Ning,Li, Guangyi,Wang, Aiqin,Cong, Yu,Wang, Xiaodong,Zhang, Tao
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- Investigation of a transition metal-assisted retro Diels-Alder reaction used in the synthesis of transition metal S2O complexes
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Treatment of 4,5-diphenyl-3,6-dihydro-1,2-dithiin-1-oxide with coordinatively unsaturated transition metal complexes resulted in the production of S2O complexes and 2,3-diphenylbutadiene.A transition metal-assisted retro Diels-Alder mechanism has been proposed for this reaction.A series of IR and 1H NMR experiments and MNDO calculations on 4,5-diphenyl-3,6-dihydro-1,2-dithiin-1-oxide have been performed to gain additional information about this transformation.
- Urove, Greg A.,Welker, Mark E.,Eaton, Bruce E.
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- A simple synthesis of the S2O source, 4,5-diphenyl-1,2-dithiin-1-oxide
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An improved procedure for the synthesis of 2,3-diphenyl-1,3-butadiene is reported along with its utilization in a simple synthesis of the S2O precursor, 4,5-diphenyl-1,2-dithiin-1-oxide.
- Fulcher,Hunter,Welker
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Read Online
- Pseudomerohedrally twinned crystal structure of 2,3-diphenylbuta-1,3-diene
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The title compound, C16H14, is twinned by reticular pseudomerohedry of twin index 2. The primitive monoclinic cell of the single crystal can be transformed into a B-centred pseudoorthorhombic supercell with a fourfold volume. The two-fold twin operation about the reciprocal a* axis of the primitive monoclinic cell is co-directional with the approximate C 2 axis of the molecule and a symmetry element of the orthorhombic supercell. A tentative twin domain model is proposed.
- Lutz, Martin,Spek, Anthony L.,Van Der Wiel, Bas C.,Van Walree, Cornelis A.
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- On the structure of cross-conjugated 2,3-diphenylbutadiene
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The structure of the cross-conjugated compound 2,3-diphenylbutadiene was investigated by single-crystal X-ray diffraction and computational methods. In the crystal structure the central butadiene fragment adopts an s-gauche geometry [-55.6(2)° torsion angle φ around the essential single bond], whereas the styrene moieties are close to planarity. MP2/6-311G* calculations show that the s-gauche conformation represents the global minimum along the φ coordinate, but also revealed the existence of an s-trans local minimum. While the crystal structure seems to reflect dominance of styrene-like conjugation, the MP2/6-311G* calculations indicate that conjugation in both the styrene and butadiene π-systems is important. An NBO orbital deletion study shows that the structure is primarily determined by (hyper)conjugation and that steric effects play a minor role. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Van Walree, Cornells A.,Van Der Wiel, Bas C.,Jenneskens, Leonardus W.,Lutz, Martin,Spek, Anthony L.,Havenith, Remco W. A.,Van Lenthe, Joop H.
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- Reductive Alkylation of Alkenyl Acetates with Alkyl Bromides by Nickel Catalysis
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Catalytic alkylation of stable alkenyl C?O electrophiles is synthetically appealing, but studies to date have typically focused on the reactions with alkyl Grignard reagents. We report herein a cross-electrophile reaction of alkenyl acetates with alkyl bromides. This work has enabled a new method for the synthesis of aliphatic alkenes from alkenyl acetates to be established that can be used to add more structural complexity and molecular diversity with enhanced functionality tolerance. The method allows for a gram-scale reaction and modification of biologically active molecules, and it affords access to useful building blocks. Preliminary mechanistic studies reveal that the NiI species plays an essential role for the success of the coupling of these two reactivity-mismatched electrophiles.
- Bai, Yunfei,Han, Guan-Yu,He, Rong-De,Liu, Xue-Yuan,Pan, Xiaobo,Pang, Xiaobo,Shu, Xing-Zhong,Zhao, Zhen-Zhen
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supporting information
(2021/12/14)
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- Iron-Catalyzed Vinylzincation of Terminal Alkynes
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Organozinc reagents are among the most commonly used organometallic reagents in modern synthetic chemistry, and multifunctionalized organozinc reagents can be synthesized from structurally simple, readily available ones by means of alkyne carbozincation. However, this method suffers from poor tolerance for terminal alkynes, and transformation of the newly introduced organic groups is difficult, which limits its applications. Herein, we report a method for vinylzincation of terminal alkynes catalyzed by newly developed iron catalysts bearing 1,10-phenanthroline-imine ligands. This method provides efficient access to novel organozinc reagents with a diverse array of structures and functional groups from readily available vinylzinc reagents and terminal alkynes. The method features excellent functional group tolerance (tolerated functional groups include amino, amide, cyano, ester, hydroxyl, sulfonyl, acetal, phosphono, pyridyl), a good substrate scope (suitable terminal alkynes include aryl, alkenyl, and alkyl acetylenes bearing various functional groups), and high chemoselectivity, regioselectivity, and stereoselectivity. The method could significantly improve the synthetic efficiency of various important bioactive molecules, including vitamin A. Mechanistic studies indicate that the new iron-1,10-phenanthroline-imine catalysts developed in this study have an extremely crowded reaction pocket, which promotes efficient transfer of the vinyl group to the alkynes, disfavors substitution reactions between the zinc reagent and the terminal C–H bond of the alkynes, and prevents the further reactions of the products. Our findings show that iron catalysts can be superior to other metal catalysts in terms of activity, chemoselectivity, regioselectivity, and stereoselectivity when suitable ligands are used.
- Hu, Meng-Yang,Huang, Qiang,Su, Yu-Xuan,Sun, Wei,Wang, Wei-Na,Zhu, Shou-Fei
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supporting information
(2022/01/08)
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- Synthesis of Alkenylboronates from N-Tosylhydrazones through Palladium-Catalyzed Carbene Migratory Insertion
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The palladium-catalyzed oxidative borylation reaction of N-tosylhydrazones has been developed. The reaction features mild conditions, broad substrate scope, and good functional group tolerance. It thus represents a highly efficient and practical method for the synthesis of di-, tri-, and tetrasubstituted alkenylboronates from readily available N-tosylhydrazones. One-pot Suzuki coupling and other transformations highlight the synthetic utility of the approach. DFT calculations have revealed that palladium-carbene formation and subsequent boryl migratory insertion are the key steps in the catalytic cycle. The high stereoselectivity observed in the formation of trisubstituted alkenylboronates has been explained by distortion-interaction analysis and NBO analysis.
- Chang, Taiwei,Huo, Jingfeng,Lei, Ming,Ping, Yifan,Wang, Jianbo,Wang, Qianyue,Wang, Rui
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p. 9769 - 9780
(2021/07/19)
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- Fluoroalkenylation of boronic acids: Via an oxidative Heck reaction
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A fluoroalkenylation of boronic acids with fluoroalkyl alkenes has been developed. The Pd-catalyzed oxidative Heck coupling reaction proceeds under an oxygen atmosphere at room temperature, in the absence of a base and/or a ligand, showing excellent practicality of the process. This simple transformation is highly stereoselective to provide only E-isomers. In addition to the general approach using alkenes with functionalized fluoroalkyl reagents, this method, by transferring an aromatic system to the electron-deficient fluoroalkyl alkene, provides an efficient alternative method to yield valuable organofluorines.
- Lee, Da Seul,Cho, Eun Jin
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p. 4317 - 4325
(2019/05/06)
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- Copper-Catalyzed Dehydrogenative Diels-Alder Reaction
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A practical and effective copper-catalyzed dehydrogenative Diels-Alder reaction of gem-diesters and ketone with dienes has been established. The active dienophiles were generated in situ via a radical-based dehydrogenation process, which reacted with a wide variety of dienes to afford various polysubstituted cyclohexene derivatives in good to excellent yields.
- Jiang, Bing,Liang, Qiu-Ju,Han, Yu,Zhao, Meng,Xu, Yun-He,Loh, Teck-Peng
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p. 3215 - 3219
(2018/06/11)
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- Highly-functionalized arene synthesis based on palladium on carbon-catalyzed aqueous dehydrogenation of cyclohexadienes and cyclohexenes
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Transition metal-catalyzed dehydrogenation is a clean oxidation method requiring no additional oxidants. We have accomplished a heterogeneous Pd/C-catalyzed aqueous dehydrogenation of 1,4-cyclohexadienes and cyclohexenes to give the corresponding highly-functionalized arenes. Furthermore, various arenes could be efficiently constructed in a one-pot manner via a Diels-Alder reaction and the following dehydrogenation.
- Yasukawa, Naoki,Yokoyama, Hiroki,Masuda, Masahiro,Monguchi, Yasunari,Sajiki, Hironao,Sawama, Yoshinari
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supporting information
p. 1213 - 1217
(2018/03/28)
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- Preparation method of conjugated diene compound
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The invention belongs to the field of fine chemicals and relevant chemical technologies and provides a preparation method of a butadiene derivative. The preparation method comprises the following steps of by taking phenylacetylene and a derivative thereof as raw materials, under the actions of a metal catalyst and an additive, performing reaction in an anhydrous organic solvent, and converting thephenylacetylene and the derivative thereof to a 2,3-di-substituted-1,3-butadiene compound. The preparation method has the beneficial effects of being simple and convenient to operate and mild in condition, being environmental friendly, having the possibility of realizing industrialization, and preparing the butadiene compound with a higher yield. The butadiene compound synthesized by utilizing the method can perform further functionalization to obtain various compounds, and then the compounds are applied to development and study of natural products, functional materials and the fine chemicals.
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Paragraph 0037; 0038; 0039; 0040
(2018/04/01)
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- Feasibility of room temperature reduction of aromatic carbonyl and nitro compounds by Zn/dil. HCl-Et2O system: An experimental and DFT study
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This experimental study is about the feasibility of the room temperature reduction of the ether soluble aromatic carbonyl/nitro compounds by atomic hydrogen. The atomic hydrogen is produced by the novel Zn/dil. HCl-Et2O reducing system (wherein dil. HCl is slowly added to the ethereal solution of Zn and substrate).This study resulted in single or mixture of anticipated reduced products in different yields. The DFT study with B3LYP/6.311g ++ (d,p) basis set revealed that the stability of the first formed free radical (energy factor) and the homo nuclear nature of the carbonyl and nitro group (charge factor) decide the yield. It is also found that the presence of –M group at o- or p- position to the carbonyl/nitro group results in the favourable modification of above-mentioned factors. The above-mentioned factors also explain the preferential reduction of nitro group when it is present along with carbonyl group. The free radical mechanism was confirmed by the formation of pinacol coupled product in one instance. In one of the reduction reactions, an unreported compound viz. the dimer of o-amino benzaldehyde was obtained in good yield.
- Rajamathe,Selvaraj
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p. 1761 - 1766
(2017/06/27)
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- From propargylic biscarbonate to diaryl[n]dendralenes
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An efficient cross-coupling reaction using a low cost carbon-supported palladium (Pd/C) catalyst for the synthesis of cross-conjugated compounds, diaryl[n]dendralenes, has been developed. The reaction of a propargylic biscarbonate with phenylboronic acid using Pd/C and phosphine ligand (S-Phos) gave 2,3-diphenyl[2]dendralene in high yield. We found that Pd/C was an effective catalyst for the synthesis of dialyl[n]dendralenes. The synthesis of various dendralenes was successfully achieved under the optimized conditions, giving dialyl [2] and [4] dendralenes in good yields.
- Hayashi, Shotaro,Kasuya, Masakatsu,Machida, Junsuke,Koizumi, Toshio
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p. 2429 - 2432
(2017/06/01)
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- Quinonediimines as redox-active organocatalysts for oxidative coupling of aryl- and alkenylmagnesium compounds under molecular oxygen
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It is revealed that N,N′-diphenyl-p-benzoquinonediimine works as a redox-active organocatalyst for the oxidative homo-coupling of aryl- and alkenylmagnesium compounds under molecular oxygen. The catalytic cycle was formally monitored by 1H NMR experiments.
- Amaya, Toru,Suzuki, Riyo,Hirao, Toshikazu
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p. 7790 - 7793
(2016/07/06)
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- Cobalt-Catalyzed Alkenylzincation of Unfunctionalized Alkynes
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While transition metal catalyzed addition reactions of arylmetal reagents to unfunctionalized alkynes have been extensively developed in the last decade, analogous reactions using alkenylmetal reagents remain rare regardless of their potential utility for the synthesis of unsymmetrical 1,3-dienes. Reported herein is the development of a cobalt/diphosphine catalyst which promotes efficient and stereoselective addition of alkenylzinc reagents to unfunctionalized internal alkynes. The resulting dienylzinc species serve as versatile intermediates for further synthetic transformations.
- Wu, Junliang,Yoshikai, Naohiko
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supporting information
p. 336 - 340
(2016/01/25)
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- Olefin Preparation via Palladium-Catalyzed Oxidative De-Azotative and De-Sulfitative Internal Cross-Coupling of Sulfonylhydrazones
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A novel reactivity of sulfonylhydrazones under Pd catalysis is described, where SO2 and N2 are formally extruded to afford the product of an apparent internal coupling reaction. The reaction is effective with both carbocyclic and heterocyclic aromatic precursors.
- Tan, Hongyu,Houpis, Ioannis,Liu, Renmao,Wang, Youchu,Chen, Zhilong
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supporting information
p. 3548 - 3551
(2015/07/28)
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- Development and Application of a Multielectron-Accepting Organic Oxidant for the Catalytic Transition-Metal-Free Oxidative Homocoupling of Grignard Reagents in Air
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Heptafluorotolyl-substituted perfluorocyclopentene acts as a four-electron oxidant for the homocoupling of Grignard reagents. It can also be used for catalytic homocoupling with a low catalyst loading (up to 2 mol %) in the presence of atmospheric oxygen. The organocatalytic cycle involves the generation of an organic radical and a perfluorocyclopentadienyl anion.
- Korenaga, Toshinobu,Nitatori, Kaoru,Muraoka, Hiroki,Ogawa, Satoshi,Shimada, Kazuaki
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supporting information
p. 5500 - 5503
(2015/11/18)
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- Oxidative homocoupling of arylboronic acids catalyzed by a 4-aminoantipyrine-Pd(II)complex
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A one-step synthesis of symmetric biaryls is reported under very mild conditions via the homocoupling reaction of substituted arylboronic acids using an air- and moisture-stable 4-aminoantipyrine-Pd(II) complex as catalyst. The reaction is conducted at a low catalyst loading of 0.1 mol% at room temperature in methanol in the presence of K2CO3 as the base and KMnO4 as the oxidant. The catalytic methodology is shown to be compatible with diverse functional groups and affords the desired biphenyls in good to excellent yields.
- Contreras-Celedón, Claudia Araceli,Rincón-Medina, José Arturo,Mendoza-Rayo, Darío,Chacón-García, Luis
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p. 439 - 442
(2015/06/30)
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- Quinonediimine-induced oxidative coupling of organomagnesium reagents
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N,N′-Diphenyl-p-benzoquinonediimine, a redox-active unit of polyaniline, efficiently induced the oxidative homocoupling of various aryl- and vinylmagnesium reagents in suppressing the side reactions, such as 1,2- or 1,4-addition reaction. Copyright
- Amaya, Toru,Suzuki, Riyo,Hirao, Toshikazu
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p. 653 - 656
(2014/01/23)
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- Masuda borylation-Suzuki coupling (MBSC) sequence of vinylhalides and its application in a one-pot synthesis of 3,4-biarylpyrazoles
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The Masuda borylation-Suzuki coupling (MBSC) sequence was successfully extended to the challenging coupling of vinylhalides with various (hetero)arylhalides using sterically hindered phosphane ligands. Starting from (hetero)arylhalides and α-bromocinnamaldehyde, the sequentially Pd-catalyzed process selectively furnishes α,β-substituted cinnamaldehydes without affecting the reactivity of the Michael system. These intermediates were implemented as entries into a novel synthesis of 3,4-diaryl 1H-pyrazoles in the fashion of a three-step one-pot procedure consisting of a Masuda borylation-Suzuki coupling and subsequent Michael addition- cyclocondensation-elimination sequence. The Royal Society of Chemistry.
- Tasch, Boris O. A.,Bensch, Lisa,Antovic, Dragutin,Müller, Thomas J. J.
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supporting information
p. 6113 - 6118
(2013/09/12)
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- Facile synthesis of dibranched conjugated dienes via palladium-catalyzed oxidative coupling of N-tosylhydrazones
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A facile and highly regioselective Pd-catalyzed oxidative coupling of N-tosylhydrazones providing efficient access to 2,3-disubstituted-1,3-butadienes has been developed. This process features readily available starting materials and mild reaction conditions. Further transformations of the obtained dibranched 1,3-dienes, through Diels-Alder reactions and indene synthesis, are also demonstrated, which reveal their great potential for synthetic utility.
- Jiang, Huanfeng,He, Li,Li, Xianwei,Chen, Huoji,Wu, Wanqing,Fu, Wei
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supporting information
p. 9218 - 9220
(2013/09/24)
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- Pd-catalyzed cross-coupling reactions of hydrazones: Regioselective synthesis of highly branched dienes
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The regioselective formation of highly branched dienes is a challenging task. Design and exploration of alternative working models to achieve such a regioselectivity to accomplish highly branched dienes is considered to be a historical advancement of Heck reaction to construct branched dienes. On the basis of the utility of carbene transfer reactions, in the reaction of hydrazones with Pd(II) under oxidative conditions, we envisioned obtaining a Pd-bis-carbene complex with α-hydrogens, which can lead to branched dienes. Herein, we report a novel Pd-catalyzed selective coupling reaction of hydrazones in the presence of t-BuOLi and benzoquinone to form the corresponding branched dienes. The utility of the Pd catalyst for the cross-coupling reactions for synthesizing branched conjugated dienes is rare. The reaction is very versatile and compatible with a variety of functional groups and is useful in synthesizing heterocyclic molecules. We anticipate that this Pd-catalyzed cross-coupling reaction will open new avenues for synthesizing useful compounds.
- Ojha, Devi Prasan,Prabhu, Kandikere Ramaiah
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p. 12136 - 12143
(2014/01/06)
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- Oxidative coupling reactions of grignard reagents with nitrous oxide
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Catalysis with laughing gas: N2O in combination with transition-metal catalysts allow the oxidative homo- and cross-coupling of Grignard reagents. The reactions can be performed under mild conditions despite the inert character of N2O. Copyright
- Kiefer, Gregor,Jeanbourquin, Loic,Severin, Kay
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supporting information
p. 6302 - 6305
(2013/07/19)
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- Synthesis of indenes via Bronsted acid catalyzed cyclization of diaryl- and alkyl aryl-1,3-dienes
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Substituted indenes can be synthesized via the Bronsted acid catalyzed cyclization of diaryl- and alkyl aryl-1,3-dienes. In this approach, treatment of symmetric or unsymmetric diaryl- and alkyl aryl-1,3-dienes with a catalytic amount of trifluoromethanesulfonic acid gives a variety of indene derivatives in good to excellent yields under mild conditions.
- Eom, Dahan,Park, Sangjune,Park, Youngchul,Ryu, Taekyu,Lee, Phil Ho
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supporting information
p. 5392 - 5395,4
(2012/12/12)
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- Synthesis of indenes via Br?nsted acid catalyzed cyclization of diaryl- and alkyl aryl-1,3-dienes
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Substituted indenes can be synthesized via the Br?nsted acid catalyzed cyclization of diaryl- and alkyl aryl-1,3-dienes. In this approach, treatment of symmetric or unsymmetric diaryl- and alkyl aryl-1,3-dienes with a catalytic amount of trifluoromethanesulfonic acid gives a variety of indene derivatives in good to excellent yields under mild conditions.
- Eom, Dahan,Park, Sangjune,Park, Youngchul,Ryu, Taekyu,Lee, Phil Ho
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supporting information
p. 5392 - 5395
(2013/01/15)
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- Synthesis of highly substituted symmetrical 1,3-dienes via organocuprate oxidation
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Oxidation of alkenyl organocuprates formed from alkenyl halides allows the formation of highly substituted symmetrical 1,3-dienes. Cuprates formed from organolithiums and Grignard reagents can be tolerated and the reaction proceeds with retention of alkenyl geometry. Georg Thieme Verlag Stuttgart New York.
- Aves, Sarah. J.,O'Connell, Kieron M. G.,Pike, Kurt G.,Spring, David R.
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supporting information; experimental part
p. 298 - 300
(2012/03/10)
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- Nickel-catalyzed dehydrogenative [4 + 2] cycloaddition of 1,3-dienes with nitriles
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Pyridines, which comprise one of the most important classes of the six-membered heterocyclic compounds, are widely distributed in nature, and the transition-metal-catalyzed [2 + 2 + 2] cycloaddition reaction of two alkynes and a nitrile is one of the most powerful methods for preparing versatile, highly substituted pyridine derivatives. However, the lack of chemo- and regioselectivity is still a crucial issue associated with fully intermolecular [2 + 2 + 2] cycloaddition. The present study developed the Ni(0)-catalyzed intermolecular dehydrogenative [4 + 2] cycloaddition reaction of 1,3-butadienes with nitriles to give a variety of pyridines regioselectively.
- Ohashi, Masato,Takeda, Ippei,Ikawa, Masashi,Ogoshi, Sensuke
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supporting information; experimental part
p. 18018 - 18021
(2011/12/13)
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- Homocoupling of arylboronic acids catalyzed by simple gold salts
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A range of arylboronic acids undergo a homocoupling reaction in the presence of catalytic amount of gold salts to yield symmetrical biaryls. Alkenylboronic acids, arylboronic esters, and arylborates also participate in the gold-catalyzed homocoupling reaction.
- Matsuda, Takanori,Asai, Taro,Shiose, Shigeru,Kato, Kotaro
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experimental part
p. 4779 - 4781
(2011/10/05)
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- Substrate-controlled regioselective cobalt(I)-catalysed 1,4-hydrovinylation reactions
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The substrate-directed regiochemistry of the cobalt-catalysed 1,4-hydrovinylation reaction is described. A variety of symmetrical and unsymmetrical 2,3-disubstituted 1,3-dienes are synthesised by ruthenium-catalysed enyne metathesis, and then reacted with a terminal alkene catalysed by cobalt(II) bromide-[1,2-bis(diphenylphosphino)ethane] [CoBr 2(dppe)] under reductive conditions. The regiochemistry of the branched 1,4-diene products is influenced by the nature of the substituents on the unsymmetrical 2,3-disubstituted 1,3-dienes. The influence of steric and electronic effects is also discussed. Georg Thieme Verlag Stuttgart New York.
- Hilt, Gerhard,Roesner, Stefan
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scheme or table
p. 662 - 668
(2011/04/15)
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- Quest for diatomic selenium
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Metallocene pentaselenides and elemental selenium were employed in an effort to generate diatomic selenium (Se2) under thermal conditions. Trapping experiments were carried out with six dienes. A successful formation of a diselenium adduct was observed in the case of 5,6-dimethylene-cyclohexa-1,3- diene (1a). The other dienes produced the corresponding dihydroselenophenes. The in-depth study of the limitations of our method to generate Se2 is described; a plausible mechanism rationalizing the observed results is proposed.
- Rys, Andrzej Z.,Schultz, Erwin K. V.,Harpp, David N.
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experimental part
p. 351 - 371
(2011/01/12)
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- Direct one-pot synthesis of 2,3-diarylbuta-1,3-diene via self-coupling of acetophenones
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A mild and straightforward route to 2,3-diarylbuta-1,3-diene is described here. By treatment with SmI2-Ac20, acetophe-none and its analogues underwent self-coupling reactions and subsequent elimination to give a series of 2,3-diarylbuta-1,3-dienes in moderate to good yields.
- Li, Jian,Li, Shaoyu,Jia, Xueshun
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experimental part
p. 1529 - 1531
(2009/04/07)
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- METHOD FOR THE PREPARATION OF A COMPOUND OF THE GENERAL FORMULA R1-R1 AND/OR R1-R2 USING HOMO AND HETERO COUPLING REACTIONS
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The present application relates to a method for the preparation of a compound of the general formula R1-R2 (I) and/or R1-R1 (II) comprising providing a compound of the general formula R1dM1Am.zM4Zn (III) or R1R2M1R3kAm.xM4Zn (IV) or R1M1R2R3kM2Am.xM4Zn (V) or R1M3R2M1.xM4Zn (VI) and reacting this compound III-VI with a quinone to produce a compound of the general formula (I) or (II) or a mixture of compounds (I) and (II). The coupling reaction can be used to prepare homo and/or hetero coupling products from well known starting materials using a quinone as redox reagent. The quinone may be recycled from the reaction.
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Page/Page column 14
(2010/11/29)
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- Transition-metal-free homocoupling of organomagnesium compounds
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(Chemical Equation Presented) Without palladium or copper: A wide range of functionalized Grignard compounds were coupled by using diphenoquinone 1 as an electron acceptor. The oxidative dimerization of alkenylmagnesium reagents proceeds with complete retention of the stereochemistry (see scheme; TBDMS = tert-butyldimethylsilyl).
- Krasovskiy, Arkady,Tishkov, Alexander,Del Amo, Vicente,Mayr, Herbert,Knochel, Paul
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p. 5010 - 5014
(2007/10/03)
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- Copper catalyzed oxidation of organozinc halides
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A wide range of organozinc substrates may be oxidized in the presence of catalytic copper to give carbon-carbon bonds in high yield. The Royal Society of Chemistry 2006.
- Su, Xianbin,Fox, David J.,Blackwell, David T.,Tanaka, Kiyotaka,Spring, David R.
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p. 3883 - 3885
(2007/10/03)
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- Utilization of industrially available 2,3-dichloro-1,3-butadiene for direct synthesis of 2,3-diaryl-1,3-butadienes
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It is shown that industrially available 2,3-dichloro-1,3-butadiene is a useful starting material for the synthesis of 2,3-diaryl-1,3-butadienes. Ni(II)-catalyzed cross-coupling reaction of 2,3-dichloro-1,3-butadiene with ArMgBr (Ar = 2-thienyl, phenyl, 4-dodecyloxyphenyl, and 4-fluorophenyl) gives the corresponding 2,3-diaryl-1,3-butadienes in good yields.
- Yamamoto, Takakazu,Yasuda, Takuma,Kobayashi, Kazuaki,Yamaguchi, Isao,Koizumi, Take-Aki,Ishii, Daisuke,Nakagawa, Masaru,Mashiko, Yoshihiro,Shimizu, Norihiro
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p. 498 - 500
(2007/10/03)
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- 3,5-Bis(trifluoromethyl)phenyl sulfones in the direct Julia-Kocienski olefination
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3,5-Bis(trifluoromethyl)phenyl (BTFP) sulfones 7 have been employed in the Julia-Kocienski olefination reaction with carbonyl compounds. Sulfones 7 are readily prepared in high yields (64-97%) from commercially available 3,5-bis(trifluoromethyl)thiophenol through an alkylation/oxidation two-step sequence. The stability of metalated BTFP sulfones has been studied and compared with heteroaryl benzothiazol-2-yl (BT), 1-phenyl-1H-tetrazol-5-yl (PT), and 1-tert-butyl-1H-tetrazol-5-yl (TBT) sulfones 9-11 under different reaction conditions. The Julia-Kocienski olefination between alkyl BTFP sulfones 7 and a wide variety of aldehydes affords the corresponding 1,2-disubstituted alkenes and dienes in good yields and stereoselectivities. This one-pot protocol can be performed using KOH at room temperature or the phosphazene bases P2-Et and P4-t-Bu at -78 °C or rt and has been successfully used in a high-yielding and stereoselective synthesis of various methoxylated stilbenes such as trimethylated resveratrol. These new reaction conditions for the Julia-Kocienski olefination reaction have been also studied with BT, PT, and TBT sulfones, giving poorer results. Methylenation of aliphatic and aromatic aldehydes, ketones, and 1,2-dicarbonyl compounds is carried out through the modified Julia olefination using BTFP methyl sulfone 7d to give terminal alkenes and dienes. Mechanistic studies of the olefination reaction between benzyl BTFP sulfone 7a and aromatic aldehydes performed by KOH-induced Smiles rearrangement of stereodefined syn- and anit-β-hydroxyalkyl BTFP sulfones indicate that the stereocontrol of the reaction is determined in the elimination step. 2005 American Chemical Society.
- Alonso, Diego A.,Fuensanta, Monica,Najera, Carmen,Varea, Montserrat
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p. 6404 - 6416
(2007/10/03)
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- Palladium-catalyzed inter- and intramolecular coupling reactions of aryl and vinyl halides mediated by indium
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(Chemical Equation Presented) Treatment of aryl and vinyl halides with 50 mol % of 100 mesh indium, 2.5 mol % of Pd-C, and 1.5 equiv of LiCl under mild conditions (DMF, 100°C, 1-3 h) could produce coupling products efficiently in good to excellent yields in which the Csp2-Csp2 bond was formed. This reagent worked equally well with both intermolecular and intramolecular coupling reactions, producing a variety of biaryls, 1,3-dienes, and cyclic compounds.
- Phil, Ho Lee,Seomoon, Dong,Lee, Kooyeon
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p. 343 - 345
(2007/10/03)
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- Synthesis of 1,1,4,4-tetrabromo-2-butenes and related compounds via desilylation-bromination of silylated 1,3-butadiene derivatives
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The combination of zirconocene-mediated coupling of silylated alkynes with a protonation-desilylation or bromination-desilylation process afforded otherwise unavailable butadiene derivatives. When (E,E)-2,3-dialkyl-1,4- bis(trimethylsilyl)-1,3-butadienes were treated with 3 equiv of Br2 in CH2Cl2, (E)-2,3-dialkyl-1,1,4,4-tetrabromo-2-butenes were obtained in excellent yields with perfect stereoselectivity.
- Xi, Zhenfeng,Liu, Xiaozhong,Lu, Jianming,Bao, Fengyu,Fan, Hongtao,Li, Zhiping,Takahashi, Tamotsu
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p. 8547 - 8549
(2007/10/03)
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- A novel and facile synthesis of 2,3-diphenylbuta-1,3-diene
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An inexpensive, simple, and high yield synthesis of the title compound is reported. In addition, some mechanistic insights into the dehydration and accompanying reactions of 2,3-diphenylbutane-2,3-diol are presented.
- Wagner,Brinker
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p. 376 - 378
(2007/10/03)
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- The synthesis of stable 1,3,4-triphenylphospholes
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The first syntheses of 1,3,4-triphenylphosphole, 2-bromo-l,3,4-phenylphosphole and 2,5-dibromo-l,3,4-triphenylphosphole are described. These phospholes, unlike most of the known derivatives, are difficult to oxidise and they and their corresponding oxides show little tendency to dimerise. The NBS mediated bromination of 1,3,4-triphenyl2,5-dihydrophosphole oxide led to the desired precursors of the corresponding phospholes and in one case unexpectedly yielded a phosphole oxide directly. Some reactions including the formation of organolithium reagents and their derivatisation are reported. McMurry reactions of derived formylphospholes to give coupled products are described and some copper mediated reactions are also discussed. The Royal Society of Chemistry 2000.
- Niemi, Tuula-A.,Coe, Paul L.,Till, Stephen J.
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p. 1519 - 1528
(2007/10/03)
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- Pd(0)-catalysed formation of diarylated dienes from propargyl carbonates and organoboron and organotin(IV) reagents
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The 1,1-dimethylbutyne-1,4-diol derivative 1 reacts with 2 mol. equiv. of organoboron (NaBPh4 arylboronic acids) and organotin(IV) reagents to give 1,1-dimethyl-2,3-disubstituted butadienes in good yield via allenylpalladium(II) and vinylidene-π-allylpalladium(II) intermediates. Unsubstituted esters 6 and butyne dicarbonate 7 lead to symmetrical dienes 8.
- Boehmer, Jutta,Grigg, Ronald
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p. 13463 - 13470
(2007/10/03)
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- The Reaction of Methylidenetriphenylphosphorane with Aromatic and Heterocyclic 1,2-Diketones.
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Treatment of both 2,2,6-trimethylthiochromane-3,4-dione (1a) and 3,3,6,8-tetramethyl-1,2,3,4-tetrahydronaphthalene-1,2-dione (1b) with one equivalent of Ph3P=CH2 affords a 1,2-methylidene ketone (3).Reaction with a further mole of the ylide gives a 1,2-diphenylphosphinoylethyl ketone (7) by a Michael addition and elimination of benzene.When the diketones (1a and 1b) are treated directly with two moles of the ylide, ring contraction occurs by an α-ketol rearrangement and a resonance stabilised ylide (10) results.Whereas benzil yields only diphenylbutadiene with anexcess of the ylide, 9,10-phenanthraquinone gives an α-hydroxyketone (15).
- Gabbutt, Christopher D.,Hepworth, John D.,Heron, B. Mark
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p. 805 - 819
(2007/10/02)
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- Grignard Addition Reactions to 1,4-Difunctionalized But-2-ynes
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Trisubstituted alkenes of E geometry have been prepared by anti addition of Grignard reagents to 1,4-difunctionalized but-2-ynes.Addition of primary, secondary and aromatic Grignard reagents to but-2-yne-1,4-diol provided (E)-2-substituted but-2-ene-1,4-diols as major products along with the corresponding 2-substituted buta-2,3-dien-1-ols.Addition of phenylmagnesium bromide to the mono- and di-methyl ethers of but-2-yne-1,4-diol gave 2,3-diphenyl-1,3-diene.Treatment of 4-dimethylaminobut-2-yn-1-ol with primary alkyl and alkenyl Grignard reagents afforded the 2-substituted anti addition product regiospecifically, stereospecifically and in high yield.Reaction of 1-dimethylamino-4-methoxybut-2-yne with butylmagnesium bromide provided only the 3-substituted anti addition product in good yield.
- Silva, Anthony N. De,Francis, Craig L.,Ward, A. David
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p. 1657 - 1672
(2007/10/02)
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- One-pot conversion of terminal alkynes into gem-disubstituted-alkenes
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A one-pot reaction of terminal alkynes with in situ generated hydrogen iodide and organozinc compounds in the presence of Pd(PPh3)4 provided a simple and useful method for the preparation of gem-disubstituted-alkenes.
- Luo, Fen-Tair,Fwu, Shiang-Long,Huang, Wen-Shu
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p. 6839 - 6840
(2007/10/02)
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- A FACILE METHOD FOR THE PREPARATION OF FUNCTIONALIZED 2,3-DISUBSTITUTED-1,3-BUTADIENES
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Functionalized 2,3-disubstituted-1,3-butadienes were readily prepared by reacting functionalized organozinc compounds with 1,4-dichloro-2-butyne or 1,4-ditosyloxy-2-butyne mediated by Cu(I) salts.
- Zhu, Lishan,Rieke, Reuben D.
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p. 2865 - 2866
(2007/10/02)
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- Synthesis and reaction chemistry of the readily available molybdenum S2O complex [MoO(S2CNEt2)2(S2O)]
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The synthesis (by S2O transfer and S2 complex oxidation) and characterization by X-ray diffraction of MoO(S2CNEt2)2(S2O) (1) is reported (monoclinic, P21/n, a = 9.4749 (15) ?, b = 21.9780 (32) ?, c = 9.6714 (16) ?, β = 107.225 (13)°, Z = 4, R(F) = 3.46%). S2O is bound to the metal in a side-on manner through both of the sulfurs. The geometry around the metal is a distorted pentagonal bipyramid with both sulfurs of S2O in the equatorial plane. In a preliminary reactivity study, 1 has been shown to effect sulfur and oxygen transfer to triphenylphosphine. Complex 1 can also be used as a template for thiosulfinate ester (RSS(O)R′) synthesis and as a reagent for oxidative coupling of carbanions.
- Brown, David S.,Owens, Catherine F.,Wilson, Bruce G.,Welker, Mark E.,Rheingold, Arnold L.
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p. 871 - 875
(2008/10/08)
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