- Unprecedented elimination of conjugated phenylthioether groups by low-valent titanocene
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The first thioether elimination reaction utilizing a low-valent titanocene has been discovered. This reaction occurs under mild conditions and affords stereospecifically a variety of dienes and styrenes. Our data suggest that this new reaction involves an
- Ribeiro, Nigel,Fetzer, Ludivine,Streiff, Stéphane,Désaubry, Laurent
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Read Online
- Contra-Thermodynamic Positional Isomerization of Olefins
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A light-driven method for the contra-thermodynamic positional isomerization of olefins is described. In this work, stepwise PCET activation of a more substituted and more thermodynamically stable olefin substrate is mediated by an excited-state oxidant an
- Zhao, Kuo,Knowles, Robert R.
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supporting information
p. 137 - 144
(2022/01/19)
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- Divergent Reactivity of α,α-Disubstituted Alkenyl Hydrazones: Bench Stable Cyclopropylcarbinyl Equivalents
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Herein we report the divergent reactivity of 2,2-dialkyl-3-(E)-alkenyl N-tosylhydrazones using Pd-catalyzed cross-coupling conditions, which enable the Z-selective synthesis of 3-aryl-1,4-dienes and gem-dialkyl vinylcyclopropanes. We found that the dialky
- Ritchie, Nina F. C.,Zahara, Adam J.,Wilkerson-Hill, Sidney M.
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supporting information
p. 2101 - 2106
(2022/02/14)
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- Gold-catalyzed [4+2] Annulations of Dienes with Nitrosoarenes as 4 π Donors: Nitroso-Povarov Reactions
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This work reports the first success of the nitroso-Povarov reaction, involving gold-catalyzed [4+2] annulations of nitrsoarenes with substituted cyclopentadienes. In this catalytic sequence, nitrosoarenes presumably attack gold-π-dienes by a 1,4-addition pathway, generating allylgold nitrosonium intermediates to complete an intramolecular cyclization. Acyclic dienes are also applicable substrates, and affording oxidative nitroso-Povarov products.
- Chen, Ching-Nung,Liu, Rai-Shung
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p. 9831 - 9835
(2019/07/04)
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- Transition-metal-free synthesis of vicinal triborated compounds and selective functionalisation of the internal C-B bond
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1,2,3-Triborated compounds can be prepared by simple nucleophilic borylation of 1,3-dienes, without the assistance of metal catalysts. Selective functionalisation of the internal C-B bond of the 1,2,3-triborated compounds, through cross-coupling with aryl
- Davenport, Elliot,Fernandez, Elena
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supporting information
p. 10104 - 10107
(2018/09/18)
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- Nickel-Catalyzed system for the cross-coupling of alkenyl methyl ethers with grignard reagents under mild conditions
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A nickel-catalyzed cross-coupling of alkenyl methyl ethers with Grignard reagents, under mild conditions, is described. These conditions allowed access to various stilbenes and heterocyclic stilbenic derivatives as well as to a potential anticancer agent DMU-212.
- Hostier, Thomas,Neouchy, Zeina,Ferey, Vincent,Gomez Pardo, Domingo,Cossy, Janine
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supporting information
p. 1815 - 1818
(2018/04/14)
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- Solvate Ionic Liquids as Reaction Media for Electrocyclic Transformations
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Solvate ionic liquids (SILs) consisting of lithium bis(trifluoromethylsulfonyl)imide dissolved in tri-or tetraglyme have recently emerged as a novel class of ionic liquids. Herein, the first use of solvate ionic liquids as a replacement for molecular solvents in electrocyclization reactions is reported. The SILs promoted both Diels-Alder and [2+2] cycloaddition reactions, compared to an appropriate molecular solvent, and 5 M lithium perchlorate in diethyl ether. The Gutmann acceptor number (AN) of these solvate ionic liquids has also been determined by 31P NMR spectroscopy to be 26.5, thus being modest Lewis acids.
- Eyckens, Daniel J.,Champion, Megan E.,Fox, Bronwyn L.,Yoganantharajah, Prusothman,Gibert, Yann,Welton, Tom,Henderson, Luke C.
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supporting information
p. 913 - 917
(2016/03/01)
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- Stereoselective synthesis of 1,3-dienes from propargylic alcohols by LiAlH4/AlCl3
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Herein we report that LiAlH4/AlCl3 is a very efficient reagent for the reductive dehydration of aryl propargylic alcohols in tetrahydrofuran solvent at reflux to give 1,3-dienes with good yields and high E selection. The reaction con
- Cui, Dong-Mei,Zhu, Kai,Chen, Li,Qi, Lang-Jun,Zhang, Cheng-Zhu,Zheng, Chen
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supporting information
p. 2380 - 2384
(2013/07/26)
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- Copper(I)-catalyzed alkylation of aryl- and alkenylsilanes activated by intramolecular coordination of an alkoxide
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Let's coordinate: Copper(I)-catalyzed cross-coupling of alkenyl- and arylsilanes with primary alkyl iodides as well as allylic and benzylic halides as C(sp3)-X electrophilic coupling partners has been realized by intramolecular activation through alkoxide coordination. This alkylation tolerates a range of functional groups including a free hydroxy group. IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene. Copyright
- Tsubouchi, Akira,Muramatsu, Daisuke,Takeda, Takeshi
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p. 12719 - 12722
(2013/12/04)
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- Palladium-catalyzed allylic fluorination of cinnamyl phosphorothioate esters
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A highly regioselective, Pd-catalyzed allylic fluorination of phosphorothioate esters is reported. This chemistry addresses several limitations of previously reported methods in which elimination and lack of reactivity were problematic. Preliminary mechanistic investigations reveal that these reactions are stereospecific and provide fluorinated products with net retention of stereochemical configuration. In analogy to other Pd-catalyzed allylic substitution reactions, this process likely proceeds through a palladium π-allyl intermediate.
- Lauer, Andrew M.,Wu, Jimmy
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supporting information
p. 5138 - 5141,4
(2012/12/12)
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- Palladium-catalyzed allylic fluorination of cinnamyl phosphorothioate esters
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A highly regioselective, Pd-catalyzed allylic fluorination of phosphorothioate esters is reported. This chemistry addresses several limitations of previously reported methods in which elimination and lack of reactivity were problematic. Preliminary mechanistic investigations reveal that these reactions are stereospecific and provide fluorinated products with net retention of stereochemical configuration. In analogy to other Pd-catalyzed allylic substitution reactions, this process likely proceeds through a palladium π-allyl intermediate.
- Lauer, Andrew M.,Wu, Jimmy
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supporting information
p. 5138 - 5141
(2013/01/15)
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- Nickel-catalyzed alkenylative cross-coupling reaction of alkyl sulfides
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A novel cross-coupling reaction of alkyl aryl sulfides with aryl Grignard reagents has been achieved to produce the alkenyl-aryl coupling products in high yields by using catalytic Ni(cod)2 and a bulky N-heterocyclic carbene ligand, SIPr.
- Ishizuka, Kentaro,Seike, Hirofumi,Hatakeyama, Takuji,Nakamura, Masaharu
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supporting information; experimental part
p. 13117 - 13119
(2010/11/05)
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- Palladium-tetraphosphine complex catalysed heck reaction of vinyl bromides with alkenes: A powerful access to conjugated dienes
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A wide variety of 1,3-dienes have been prepared by the Heck vinylation of vinyl bromides using [Pd(η3-C3H5)Cl] 2/cis,cis,cis-1,2,3,4-tetrakis[(diphenylphosphino)methyl] cyclopentane (Tedicyp) as the catalyst precursor. Both α- and β-substituted vinyl bromides undergo the Heck reaction with functionalised alkenes such as acrylates, enones, styrenes or a vinyl sulfone, and also with nonfunctionalised alkenes such as dec-1-ene, leading stereoselectively, in most cases, to the corresponding E- or E,E-1,3-dienes in good yields. Furthermore, this catalyst can be used at low loading for several reactions. Georg Thieme Verlag Stuttgart.
- Lemhadri, Mhamed,Battace, Ahmed,Berthiol, Florian,Zair, Touriya,Doucet, Henri,Santelli, Maurice
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p. 1142 - 1152
(2008/12/22)
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- Vinyl tris(trimethylsilyl)silanes: substrates for Hiyama coupling
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The oxidative treatment of vinyl tris(trimethylsilyl)silanes with hydrogen peroxide in aqueous sodium hydroxide in tetrahydrofuran generates reactive silanol or siloxane species that undergo Pd-catalyzed cross-couplings with aryl, heterocyclic, and alkenyl halides in the presence of Pd(PPh3)4 and tetrabutylammonium fluoride. Hydrogen peroxide and base are necessary for the coupling to occur while activation of the silanes with fluoride is not required. The conjugated and unconjugated tris(trimethylsilyl)silanes serve as good cross-coupling substrates. The (E)-silanes undergo coupling with retention of stereochemistry while coupling of (Z)-silanes occurred with lower stereoselectivity to produce an E/Z mixture of products.
- Wang, Zhizhong,Pitteloud, Jean-Philippe,Montes, Lucresia,Rapp, Magdalena,Derane, Djenny,Wnuk, Stanislaw F.
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p. 5322 - 5327
(2008/09/21)
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- Studies on the heck reaction with alkenyl phosphates: Can the 1,2-migration be controlled? Scope and limitations
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A catalyst system was identified which promotes the Heck coupling of nonactivated vinyl phosphates with electron deficient alkenes providing a new entry to diene products from simple and readily accessible starting materials. In contrast to our earlier wo
- Ebran, Jean-Philippe,Hansen, Anders L.,Gogsig, Thomas M.,Skrydstrup, Troels
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p. 6931 - 6942
(2008/02/08)
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- 3,5-Bis(trifluoromethyl)phenyl sulfones in the Julia-Kocienski olefination - Application to the synthesis of tri- and tetrasubstituted olefins
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3,5-Bis(trifluoromethyl)phenyl (BTFP) sulfones 8a-d are successfully employed in the modified Julia olefination reaction with carbonyl compounds employing phosphazene base P4-tBu at room temp. in THF, affording tri- and tetrasubstituted olefins in good yi
- Alonso, Diego A.,Fuensanta, Monica,Najera, Carmen
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p. 4747 - 4754
(2007/10/03)
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- Heck reaction of vinyl bromides with alkenes in the presence of a tetraphosphine/palladium catalyst
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Through the use of [PdCl(C3H5)]2- cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane as a catalyst, a range of vinyl bromides undergo Heck reaction with a wide variety of alkenes leading selectively to the corresponding 1,3-dienes in good yields. Furthermore, it can be used at low loading even for reactions of sterically hindered vinyl bromides.
- Berthiol, Florian,Doucet, Henri,Santelli, Maurice
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p. 841 - 844
(2007/10/03)
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- Synthesis of 3,6-dihydro-2H-pyran-2-ones via cationic palladium(II) complex-catalyzed tandem [2+2] cycloaddition-allylic rearrangement of ketene with α,β-unsaturated aldehydes and ketones
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Treatment of ketene with α,β-unsaturated aldehydes and ketones in the presence of [Pd(dppb)(PhCN)2](BF4)2 leads to the formation of 4-vinyloxetan-2-ones, which rearrange under the conditions to give 3,6-dihydro-2H-pyran-2-ones in a variety of yields, depending on the substituents. Asymmetric induction with up to 57% de has been achieved by using α,β-unsaturated aldehydes bearing an asymmetric carbon center at the β-position. A zwitterion generated by heterolytic cleavage of the C(4)-O bond of the 4-vinyloxetan-2-one is considered to be an intermediate in the allylic rearrangement. Ethanolysis of 3,6-dihydro-6-methyl-2H-pyran-2-one under acid conditions, followed by saponification of the resulting ethyl 2,4-hexadienoate (ethyl sorbate), gives sorbic acid in 90% yield.
- Hattori, Tetsutaro,Suzuki, Yutaka,Ito, Yuuichi,Hotta, Daido,Miyano, Sotaro
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p. 5215 - 5223
(2007/10/03)
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- The simultaneous in-situ generation of aldehydes and phosphorus ylides: A convenient multi-step one-pot olefination protocol
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The lithium α-(dimethylamino)alkoxides resulting from the nucleophilic addition of an organolithium reagent to N,N-dimethylformamide are basic enough to deprotonate alkyltriphenylphosphonium salts suspended in tetrahydrofuran. The aldehydes liberated by t
- Wang, Qian,Wei, Heng-Xu,Schlosser, Manfred
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p. 3263 - 3268
(2007/10/03)
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- Selective reaction of π-allyl(alkyloxy)palladium(II) complexes toward β-decarbopalladation, β-dehydropalladation, and reductive elimination
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Depending on the kind of R1 and R2, cyclic carbonates 1, in the presence of 10 mol% of Pd(PPh3)4 and 10 equiv of paraformaldehyde, selectively undergo three types of reaction: 1 (R1, R2 ≠ H) give dienes 3 exclusively; 1 (R1 = R2 = H and R1 ≠H, R2 = H) furnish 6-vinyl-1,3- dioxanes 5 exclusively, while 1 (R1 = H, R2 ≠ H) give rise to 4-pentenyl formates 4 selectively (together with 3 as the minor products).
- Harayama, Hiroto,Kimura, Masanari,Tanaka, Shuji,Tamara, Yoshinao
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p. 8475 - 8478
(2007/10/03)
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- Highly stereo and chemoselective iron-catalyzed alkenylation of organomagnesium compounds
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In the presence of Fe(acac)3, Grignard reagents react readily with alkenyl halides (X = I, Br or Cl) in a THF/NMP mixture to give the cross-coupling products in high yields with an excellent stereoselectivity (≤99.5%). The scope of the reaction is very broad since a vast array of functional groups are tolerated (esters, nitriles, aromatic or aliphatic halides and even ketones). The procedure reported herein is an interesting alternative to the classical Pd- or Ni-catalyzed reactions, especially for preparative organic chemistry.
- Cahiez, Gerard,Avedissian, Hovsep
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p. 1199 - 1205
(2007/10/03)
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- Cobalt-catalyzed alkenylation of organomagnesium reagents
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Alkenyl iodides, bromides and chlorides react with organomagnesium reagents in THF, in the presence of Co(acac)2 and NMP (9 to 4 equiv.), to give the cross-coupling products in good yields. The reaction is chemoselective (aryl or alkyl bromides, esters and ketones) and stereoselective (≤ 99.5%).
- Cahiez, Gerard,Avedissian, Hovsep
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p. 6159 - 6162
(2007/10/03)
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- Regioselective 1,4-addition of ammonia to 1-arylalka-1,3-dienes and 1-aryl-4-phenylbuta-1,3-dienes by photoinduced electron transfer
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The photoamination of 1-arylalka-1,3-dienes 1a-f and 1-aryl-4-phenylbuta-1,3-dienes 1g-k with NH3 in the presence of p-dicyanobenzene (DCB) gives 4-amino-1-arylalk-2-enes 2a-f and 1-amino-1,4-diarylbut-2-enes 2g-k, respectively. The photoamination proceeds by nucleophilic addition of NH3 to the cation radicals of 1+. generated by photoinduced electron transfer to DCB. The regiochemistry of 2 is related to the distribution of the positive charge in 1+. calculated by the PM3-UHF/RHF method, the stability of the aminated radicals formed by the addition of NH3 to 1+. and the stability of the aminated anion formed by the reduction of the aminated radicals by DCB-.. The stabilities of these intermediates are estimated by the calculation of the heat of formation by the PM3-UHF/RHF method. Distributions of the positive charge in 1+. and the stabilities of the aminated anion show a good agreement with the product analysis.
- Kojima, Ryuji,Yamashita, Toshiaki,Tanabe, Kimiko,Shiragami, Tsutomu,Yasuda, Masahide,Shima, Kensuke
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p. 217 - 222
(2007/10/03)
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- Polymer-bound palladium-catalyzed cross-coupling of organoboron compounds with organic halides and organic triflates
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The polymer-bound palladium-catalyzed cross-coupling reaction of electrophiles (i.e., halides and triflates) with oganoboron compounds to form carbon-carbon bonds was achieved at mild conditions with very high activity in the Suzuki coupling reaction. The polymeric catalyst can be easily separated from a reaction mixture and reused more than 10 times with no decrease in activity.
- Jang, Su-Bum
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p. 1793 - 1796
(2007/10/03)
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- Tandem [2 + 2] cycloaddition-cycloreversion reactions in highly polar media: A convergent one-pot entry to substituted alkenes and dienes
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Reaction at room temperature between acyl chlorides and aromatic or α,β-unsaturated aldehydes in the presence of a tertiary base and in 5M lithium perchlorate-diethyl ether (5M LPDE) as solvent yields substituted alkenes in satisfactory yields. The reaction is formally conceived as a [2 + 2] cycloaddition between the aldehyde and the in situ formed ketene, followed by thermal decarboxylation of the intermediate 2 oxetanone. Ketene itself yields α,β-unsaturated acids under these reaction conditions.
- Arrastia, Iosune,Cossio, Fernando P.
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p. 7143 - 7146
(2007/10/03)
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- Highly chemo- and stereoselective Fe-catalyzed alkenylation of organomanganese reagents
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Organomanganese chlorides react with alkenyl iodides, bromides and chlorides in the presence of 3% Fe(acac)3. The reaction takes place under very mild conditions (THF-NMP, rt, 1h) to afford the substituted olefin in excellent yields with a high stereo- and chemoselectivity. Thus an unprotected keto alkenyl chloride selectively gives the corresponding keto olefin. From a preparative point of view, this procedure is the first real alternative to the Pd- and Ni-cross coupling reaction used until now.
- Cahiez, Gerard,Marquais, Sophie
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p. 1773 - 1776
(2007/10/03)
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- Subsituted 4-(2-alkenylsulfinyl)morpholines : preparation and conversion into the corresponding sulfinic acids and esters. Stereochemistry of olefin formation by hydrolytic desulfinylation of allylic sulfinamides.
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By reaction with 4-(chlorosulfenyl)morpholine in the presence of triethylamine, several substituted allylic alcohols have been converted into the title sulfinamides.As a complementary method, the new α-lithio allylic sulfinamides have been prepared and efficiently alkylated with organic halides.The boron trifluoride-etherate catalyzed treatment of the allylic sulfinamides with simple saturated alcohols provided the corresponding alkyl sulfinates while propargylic and allylic alcohols opened a route to various α,α'-bis-unsaturated sulfones.Efficient conditions for the acid-catalyzed hydrolysis of allylic sulfinamides are described and some allylic sulfinic acids bearing an electron-withdrawing group were isolated.Smooth fragmentation of the homoconjugated sulfinic acids gave the corresponding (E)-olefins stereoselectively. - Key words: sigmatropic rearrangement / allylic sulfinamide / allylic sulfinic ester / organolithium derivative / sulfone / retro-ene reaction / sulfur dioxide elimination / stereochemistry
- Baudin, Jean-Bernard,Julia, Sylvestre
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p. 196 - 214
(2007/10/02)
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- Use of Samarium Diiodide as an Alternative to Sodium/Mercury Amalgam in the Julia-Lythgoe Olefination
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Studies into the use of samarium diiodide (SmI2) in the reductive elimination of 1,2-acetoxy sulfones and the reductive cleavage of vinyl sulfones are reported.Parallel investigations with sodium/mercury amalgam (Na/Hg) revealed over-reduction in several
- Keck, Gary E.,Savin, Kenneth A.,Weglarz, Michael A.
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p. 3194 - 3204
(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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- Stereochemistry of direct olefin formation from carbonyl compounds and lithiated heterocyclic sulfones
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The conditions for the title reaction were studied for the 2-benzothiazole and 2-pyridine series and for some examples in the 2-pyrimidine series.The olefin preparations were generally observed to be more efficient for 2-BT-sulfone systems.From the data of the hundred cases studied, it can be concluded that (E)-olefins are obtained: (i) from saturated BT-sulfones and aromatic aldehydes; and (ii) from benzylic BT-sulfones and branched saturated aldehydes (isobutyraldehyde, pivalaldehyde) or α,β-ethylenic or aromatic aldehydes. (Z)-olefins arise: (i) fom propargylic BT-sulfones and saturated or aromatic aldehydes; and (ii) from allylic or benzylic Pyr-sulfones and saturated aldehydes.Possible mechanisms for this new olefination procedure were examined. - heteroaromatic sulfones, organolithium derivatives, intramolecular ipso reactions, stereochemistry, elimination, olefination.
- Baudin, J. B.,Hareau, G.,Julia, S. A.,Lorne, R.,Ruel, O.
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p. 856 - 878
(2007/10/02)
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- Stereochemistry of the olefin formation from anti and syn heterocyclic β-hydroxy sulfones.
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Reaction of aldehydes R2-CHO with the new lithio derivatives of 2-benzothiazoles or pyridines R1-CH2-SO2-Het afforded the corresponding β-hydroxy sulfones which are stable in the pyridine series and generally unstable in the benzothiazole series except for anti derivatives 10a and 20c. t-Butyl-dimethyl silyl ethers of all the heterocyclic β-hydroxy sulfones have been obtained by oxidation of the corresponding anti and syn sulfides, which have been stereoselectively prepared from the epoxides 17, 19, 21 and 23.The lithium or tetrabutylammonium alkoxides of heterocyclic β-hydroxy sulfones undergo an intramolecular addition to the neighboring C=N group followed by an S to O benzothiazole (or pyridine) transfer, and simultaneous extrusion of sulfur dioxide, ejection of benzothiazol-2(3H)-one anion and formation of the corresponding olefins.From the data of twenty cases studied, it can be concluded that the final elimination is entirely antiperiplanar only for the alkoxides of β-hydroxy-BT- or Pyr-sulfones anti or syn bearing saturated aliphatic chains R1 and R2 and for anti derivatives with R1 = R2 = C6H5.Due to their equilibration however, the alkoxides of numerous derivatives of heterocyclic (3-methylbut-2-enyl) or (phenylmethyl) sulfones do not follow entirely the above antiperiplanar elimination. Keywords: heteroaromatic sulfones / intramolecular ipso reaction / organolithium derivatives / stereochemistry / eliminations / olefination
- Baudin, J. B.,Hareau, G.,Julia, S. A.,Ruel, O.
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p. 336 - 357
(2007/10/02)
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- A HIGHLY STEREOSELECTIVE SYNTHESIS OF SUBSTITUTED BUTADIENES AND CONJUGATED POLYENES
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A highly stereoselective synthesis of 1,3-butadienes and its higher enyl analogs has been developed through thermal dehydrative ring opening of cyclopropyl carbinols in dimethylsulphoxide.
- Patro, Balaram,Ila, Hiriyakkanavar,Junjappa, Hiriyakkanavar
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p. 809 - 812
(2007/10/02)
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- Stereoselective E and Z Olefin Formation by Wittig Olefination of Aldehydes with Allylic Phosphorus Ylides. Stereochemistry
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Sterically crowded allylic tributylphosphorus ylides such as β-γ-disubstituted allylic ylides react with various aldehydes to afford E olefins with high stereoselectivity (E>92percent).As the steric demand of the ylides was decreased, bulky aldehydes were required to achieve high E selectivity.On the other hand, predominant or exclusive formation of Z olefins was achieved by using allylic triphenylphosphorus ylides and tertiary aldehydes like pivaldehyde, while the combination of allylic triphenylphosphorus ylides and such large secondary aldehydes as cyclohexanecarboxaldehyde led to E olefin formation under the lithium salt free conditions.The distinct lithium salt effect was observed in the reaction effected with triphenylphosphorus ylides.The origin of the observed E or Z selectivity can be reasonably explained according to Vedejs' rationale on the Wittig reaction stereochemistry.
- Tamura, Rui,Saegusa, Koji,Kakihana, Masato,Oda, Daihei
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p. 2723 - 2728
(2007/10/02)
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- (E)-(2-Bromoethenyl)diisopropoxyborane. A New Building Block for (E)-Olefins
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(E)-(2-Bromoethenyl)diisopropoxyborane is a useful precursor for the synthesis of (E)-olefins by the stepwise cross-coupling reaction with organozinc chlorides and then with organic halides in the presence of a base, both catalyzed by Pd complex.
- Hyuga, Satoshi,Yamashina, Naoko,Hara, Sheji,Suzuki, Akira
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p. 809 - 812
(2007/10/02)
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- 2-Allylisourea as a Starting Material for Palladium-Catalyzed Wittig-Type Allylidenation of Aldehydes
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2-Allylic-substituted isoureas underwent Wittig-type allylidenation of aldehydes in the presence of triphenylphosphine and 2 molpercent of to give the corresponding conjugated olefins in tolerable to good yields.
- Inoue, Yoshio,Toyofuku, Masanori,Hashimoto, Harukichi
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p. 1279 - 1280
(2007/10/02)
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- Novel and Convenient Method for the Stereo- and Regiospecific Synthesis of Conjugated Alkadienes and Alkenynes via the Palladium-Catalyzed Cross-Coupling Reaction of 1-Alkenylboranes with Bromoalkenes and Bromoalkynes
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Details of a new and general method for the stereo- and regiospecific synthesis of conjugated alkadienes and alkenynes are described.The reaction of (E)- or (Z)-1-alkenyldisiamylboranes, or 2-((E)-1-alkenyl)-1,3,2-benzodioxaboroles readily obtainable by hydroboration, with either (E)- or (Z)-1-alkenyl bromides in the presence of a catalytic amount of tetrakis(triphenylphosphine)palladium and bases such as sodium alkoxides gives the corresponding (E,E)-, (E,Z)-, (Z,E)-,or (Z,Z)-conjugated alkadienes stereo- and regiospecifically, while retaining the configurations of both the strating alkenylboranes and bromoalkenes.The reaction of (E)- and (Z)-1-alkenyldisiamylboranes with 1-bromoalkynes similarly provides a stereo- and regiospecific synthesis of conjugated (E)- and (Z)-alkenynes.A mechanism of this cross-coupling reaction, which involves the transmetalation between a 1-alkenylborane and an alkoxypalladium(II) complex generated through the metathetical displacement of a halogen atom from R(Pd(II)X with sodium alkoxide, is proposed.
- Miyaura, Norio,Yamada, Kinji,Suginome, Hiroshi,Suzuki, Akira
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p. 972 - 980
(2007/10/02)
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- Reactions of ?-Allylic Palladium Intermediates with Amines
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Several dimeric ?-allylic palladium chloride complexes have been prepared by addition of aryl-, hydrido-, and (carbomethoxy)palladium chlorides, prepared in situ, to various conjugated dienes.Stoichiometric reactions of several of these complexes with secondary amines were carried out and the influence of added ligands and changes in the anions in the complexes on the reactions were noted.The stoichiometric reactions were then compared to similar catalytic reactions.The evidence suggests that the products formed in the palladium-catalyzed reactions of aryl iodides and bromides with conjugated dienes and secondary amines to form arylated dienes and allylic amines involve ?-allylic palladium complexes as intermediates.
- Stakem, Francis, G.,Heck, Richard F.
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p. 3584 - 3593
(2007/10/02)
-