- Tuning of regioselectivity in the coupling reaction involving allenic/propargylic palladium species
-
Two different types of coupling patterns for the Pd(O)-catalyzed coupling reaction of allenic/propargylic zinc reagents with organic halides or propargylic carbonates (acetate) with the corresponding organometallic reagents were observed. After studying the controlling factors on the regioselectivity of this reaction, we demonstrated that the steric hindrance of both reactants and the types of organic halides determine the regioselectivity of this coupling reaction. By subtle choosing of the substrates, the regioselectivity can be tuned. On the basis of these results, new methodologies for the highly regio- and stereoselective synthesis of 6-substituted hex-5-yn-2-enoates and 4,6-dialkylhexa-2,4,5-trienoates have been developed. Some of the products synthesized by the carbonate protocol cannot be prepared by the lithiation protocol because the regioselectivity of lithiation of dialkyl-substituted internal alkynes is an intrinsic problem.
- Ma, Shengming,Zhang, Aibin
-
-
Read Online
- Photoredox-Catalyzed α-Aminoalkylcarboxylation of Allenes with CO2
-
The photoredox-catalyzed α-aminoalkylcarboxylation of aryl allenes with CO2 and N,N-dimethylanilines is reported for the first time (26 examples, up to 96% yield). In the case of electron-deficient allenes, good regioselectivity was observed (up to 94:6), exclusively generating kinetic products over thermodynamic products. This protocol is a novel synthetic method for highly functionalized β,γ-unsaturated γ-aminobutyric esters.
- Hahm, Hyungwoo,Baek, Doohyun,Kim, Dowon,Park, Seongwook,Ryoo, Jeong Yup,Hong, Sukwon
-
supporting information
p. 3879 - 3884
(2021/05/29)
-
- Synthesis of Polycyclic Aromatic Hydrocarbons Decorated by Fluorinated Carbon Acids/Carbanions
-
The carboarylation reaction of biphenyl-alkynes was successfully triggered by electrophilic attack of 1,1-bis(triflyl)ethylene on the alkyne moiety to give polycyclic aromatic hydrocarbons (PAHs) decorated by superacidic carbon acid functionality. Neutralisation of thus obtained acids with NaHCO3 yielded the corresponding sodium salts, which showed improved solubility in both aqueous and organic solvents.
- Hoshikawa, Shoki,Yanai, Hikaru,Martín-Mejías, Irene,Lázaro-Milla, Carlos,Aragoncillo, Cristina,Almendros, Pedro,Matsumoto, Takashi
-
supporting information
p. 16112 - 16116
(2021/10/12)
-
- Regioselective Iron-Catalysed Cross-Coupling Reaction of Aryl Propargylic Bromides and Aryl Grignard Reagents
-
An iron-catalysed Kumada-type cross-coupling reaction between aryl substituted propargylic bromides and arylmagnesium reagents has been developed. Propargylic coupling products were the main or only outcome, and propargyl/allene regioselectivity was shown to depend on the electronic nature of the substituents on the triple bond of the substrate and on the arylmagnesium halide. Best selectivities were observed when electron donating substituents were present in either reagent. The process is stereoespecific, occurs with configuration inversion and no carbon-based radicals seem to be involved in the mechanism. (Figure presented.).
- Manjón-Mata, Inés,Quirós, M. Teresa,Bu?uel, Elena,Cárdenas, Diego J.
-
supporting information
p. 146 - 151
(2019/12/11)
-
- Regioselective Diboron-Mediated Semireduction of Terminal Allenes
-
A method for the regioselective reduction of the terminal double bond of 1,1-disubstituted allenes has been developed. In the presence of a palladium catalyst, tetrahydroxydiboron and stoichiometric water, allene semireduction proceeds in high yield to afford Z-alkenes selectively.
- Gates, Ashley M.,Santos, Webster L.
-
supporting information
p. 4619 - 4624
(2019/12/11)
-
- A convenient access to allylic triflones with allenes and triflyl chloride in the presence of (EtO)2P(O)H
-
A simple method for the preparation of allylic triflones from allenes and triflyl chloride in the presence of (EtO)2P(O)H has been developed. The features of this reaction are catalyst-free and simple starting substrates. This method tolerates diverse functional groups and substituted allylic triflones are obtained in moderate to good yields.
- Ni, Jixiang,Jiang, Yong,An, Zhenyu,Lan, Jingfeng,Yan, Rulong
-
supporting information
p. 7343 - 7345
(2019/06/27)
-
- Trifluoromethylation of Allenes: An Expedient Access to α-Trifluoromethylated Enones at Room Temperature
-
A silver(I) catalyzed regioselective trifluoromethylation of allenes using Langlois's salt (NaOSOCF3) is demonstrated. This transformation enables direct expedient access to α-trifluoromethylated acroleins, which are valuable synthons for a number of pharmaceuticals and agrochemicals containing vinyl-CF3 moieties. Versatility of this trifluoromethylation method has been established with good yield and excellent regioselectivity. Preliminary experiments and computational studies were carried out to elucidate the mechanistic insight of this protocol.
- Brochetta, Massimo,Borsari, Tania,Gandini, Andrea,Porey, Sandip,Deb, Arghya,Casali, Emanuele,Chakraborty, Arka,Zanoni, Giuseppe,Maiti, Debabrata
-
supporting information
p. 750 - 753
(2019/01/04)
-
- Chlorination of phenylallene derivatives with 1-chloro-1,2-benziodoxol-3-one: Synthesis of vicinal-dichlorides and chlorodienes
-
Allyl and vinyl chlorides represent important structural motifs in organic chemistry. Herein is described the chemoselective and regioselective reaction of aryl- and α-substituted phenylallenes with the hypervalent iodine (HVI) reagent 1-chloro-1,2-benz-iodoxol-3-one. The reaction typically results in vicinal dichlorides, except with proton-containing α-alkyl substituents, which instead give chlorinated dienes as the major product. Experimental evidence suggests that a radical mechanism is involved.
- Zhao, Zhensheng,Murphy, Graham K.
-
supporting information
p. 796 - 802
(2018/04/16)
-
- Copper-Catalyzed Difunctionalization of Allenes with Sulfonyl Iodides Leading to (E)-α-Iodomethyl Vinylsulfones
-
A highly regioselective iodosulfonylation of allenes in the presence of CuI and 1,10-phenanthroline has been developed for the synthesis of various useful (E)-α-iodomethyl vinylsulfones in moderate to excellent yields. This practical reaction is fast, operationally simple, and in particular, proceeds under very mild conditions to afford the target products with high regio- and stereoselectivity. The selectivity was illustrated by a conceptual DFT analysis.
- Lu, Ning,Zhang, Zhiguo,Ma, Nana,Wu, Conghui,Zhang, Guisheng,Liu, Qingfeng,Liu, Tongxin
-
supporting information
p. 4318 - 4322
(2018/07/29)
-
- Fluorinative Rearrangements of Substituted Phenylallenes Mediated by (Difluoroiodo)toluene: Synthesis of α-(Difluoromethyl)styrenes
-
Phenylallenes undergo fluorinative rearrangement upon the action of (difluoroiodo)toluene in the presence of 20 mol % BF3?OEt2 to yield α-difluoromethyl styrenes. This unprecedented reaction was entirely chemoselective for the internal allene π bond, and showed remarkable regioselectivity during the fluorination event. Substituted phenylallenes, phenylallenes possessing both phenyl- and α-allenyl substituents, and diphenylallenes were investigated, and good functional-group compatibility was observed throughout. The ease with which allenes can be prepared on a large scale, and the operational simplicity of this reaction allowed us to rapidly access fluorine-containing building blocks that have not been accessed by conventional deoxyfluorination strategies.
- Zhao, Zhensheng,Racicot, Léanne,Murphy, Graham K.
-
supporting information
p. 11620 - 11623
(2017/09/11)
-
- Iodothiocyanation/Nitration of Allenes with Potassium Thiocyanate/Silver Nitrite and Iodine
-
Direct strategies for the iodothiocyanation and iodonitration of allenes have been developed. In this process, potassium thiocyanate/silver nitrite and molecular iodine are used as the source of SCN, ONO2and iodine to provide the desired products in moderate to good yields with high stereoselectivity. (Figure presented.).
- Yang, Xiaodong,She, Yue,Chong, Ya,Zhai, Huichun,Zhu, He,Chen, Baohua,Huang, Guosheng,Yan, Rulong
-
supporting information
p. 3130 - 3134
(2016/10/09)
-
- Synthesis of terminal allenes through copper-mediated cross-coupling of ethyne with N-tosylhydrazones or α-diazoesters
-
Ethyne is employed as coupling partner in coppermediated cross-coupling reactions with N-tosylhydrazones and α-diazoacetate, leading to the development of a new synthetic method for terminal allenes. With this novel coupling method, the terminal allenes w
- Ye, Fei,Wang, Chengpeng,Ma, Xiaoshen,Hossain, Mohammad Lokman,Xia, Ying,Zhang, Yan,Wang, Jianbo
-
p. 647 - 652
(2016/09/12)
-
- Palladium-catalyzed insertion of an allene into an aminal: Aminomethylamination of allenes by C-N bond activation
-
A new and atom-economic palladium-catalyzed aminomethylamination of allenes with aminals by C-N bond activation is described. This direct and operationally simple method provides a fundamentally novel approach for the synthesis of 1,3-diamines. Mechanistic studies suggest that a unique cationic π-allylpalladium complex containing an aminomethyl moiety is generated as a key intermediate through the carbopalladation of the allene with a cyclometalated palladium-alkyl species.
- Hu, Jianhua,Xie, Yinjun,Huang, Hanmin
-
supporting information
p. 7272 - 7276
(2014/07/21)
-
- Lewis and Bronsted acid cocatalyzed reductive deoxyallenylation of propargylic alcohols with 2-nitrobenzenesulfonylhydrazide
-
Reductive deoxyallenylation of sterically hindered tertiary propargylic alcohols was realized on reaction with 2-nitrobenzenesulfonylhydrazide (NBSH) by the combined use of Lewis and Bronsted acid catalysts. This method features a broad substrate scope, m
- Liu, Zhaohong,Liao, Peiqiu,Bi, Xihe
-
supporting information
p. 17277 - 17281
(2015/02/05)
-
- Highly selective cobalt-mediated [6 + 2] cycloaddition of cycloheptatriene and allenes
-
[6 + 2] Cycloadditions between cycloheptatrienes with allenes have been investigated. Cobalt salts were found to promote this transformation efficiently. Moreover, this reaction was found to be highly selective since only one regioisomer was obtained with an excellent E/Z-selectivity.
- Clavier, Herve,Jeune, Karel Le,Riggi, Innocenzo De,Tenaglia, Alphonse,Buono, Gerard
-
supporting information; experimental part
p. 308 - 311
(2011/04/15)
-
- Lewis acid promoted reactions of ethenetricarboxylates with allenes: Synthesis of indenes and γ-lactones via conjugate addition/cyclization reaction
-
(Figure presented) Indenes are important core structures in organic chemistry. Few simple arylallenes have been used to construct indene skeletons by Friedel-Crafts reaction. Lewis acid catalyzed reaction of ethenetricarboxylates 1 and arylallenes has been examined in this study. The reaction of arylallenes and ethenetricarboxylate triesters with SnCl4 gave indene derivatives efficiently, via a conjugate addition/Friedel-Crafts cyclization reaction. On the other hand, the reactions of 1,1-diethyl 2-hydrogen ethenetricarboxylate and arylallenes or alkylallenes with SnCl4 at -78 °C or room temperature and subsequent treatment with Et3N gave γ-lactones. The reactions of triethyl ethenetricarboxylate and 1,1-dialkylallenes with SnCl4 at room temperature also gave γ-lactones.
- Yamazaki, Shoko,Yamamoto, Yuko,Fukushima, Yugo,Takebayashi, Masachika,Ukai, Tetsuma,Mikata, Yuji
-
supporting information; experimental part
p. 5216 - 5222
(2010/09/05)
-
- Ruthenium catalyzed C-C bond formation via transfer hydrogenation: Branch-selective reductive coupling of allenes to paraformaldehyde and higher aldehydes
-
(Chemical Equation Presented) Under the conditions of ruthenium-catalyzed transfer hydrogenation employing 2-propanol as the terminal reductant, 1,1-disubstituted allenes 1a-h engage in reductive coupling to paraformaldehyde to furnish homoallylic alcohol
- Ngai, Ming-Yu,Skucas, Eduardas,Krische, Michael J.
-
supporting information; experimental part
p. 2705 - 2708
(2009/05/26)
-
- Azo-coupling and reduction of cyclopropanediazonium ions in the reactions with polyhydroxyarenes and aminophenols
-
A reaction of cyclopropanediazonium ion, generated by decomposition of N-cyclopropyl-N-nitrosourea upon treatment with potassium or cesium carbonates, with various poly-hydroxyarenes and aminophenols has been studied. The reaction of azo-coupling proceeds with phloroglucinol, resorcinol, 3-methoxy- and 3-aminophenol giving rise to mono-, bis-, and tris(cyclopropylazo)arenes as the major products. Oxidizable phenols such as hydro-quinone, 2-methoxy-, 4-amino-, and 2-aminophenol give products of radical transformations with participation of cyclopropyl radical.
- Shulishov,Klimenko,Korolev,Kostyuchenko,Okonnishnikova,Tomilov
-
scheme or table
p. 1703 - 1711
(2011/04/23)
-
- Palladium-catalyzed cross-coupling reaction of alkynylzincs with benzylic electrophiles
-
The reaction of alkynylzinc bromides with benzyl bromides or chlorides in the presence of a catalytic amount of Pd(DPEphos)Cl2 in THF at 23°C cleanly produces the corresponding benzylated alkynes in 73-97% yields. With 10-3 mol % of Pd(DPEphos)Cl2, the maximum turnover number of 7.1 × 104 has been observed for the formation of PhCCCH2Ph.
- Qian, Mingxing,Negishi, Ei-Ichi
-
p. 2927 - 2930
(2007/10/03)
-
- Cross-coupling of alkyl halides with aryl Grignard reagents catalyzed by a low-valent iron complex
-
A striking reversal of the usual reactivity pattern of aryl Grignard reagents is observed for reactions in the presence of catalytic amounts of the "bare" ferrate complex [Li(tmeda)]2[Fe(C2H 4)4] (1). Highly reduced iron-magnesium clusters may play a decisive role in the exceptionally facile and chemoselective cross-coupling reaction with alkyl halides (see scheme).
- Martin, Ruben,Fuerstner, Alois
-
p. 3955 - 3957
(2007/10/03)
-
- Cyclopropanation of vinylidenecyclopropanes. Synthesis of 1-(dihalomethylene)spiropentanes
-
Synthesis of 1-(dihalomethylene)spiropentanes via cyclopropylidenecyclopropanes generated by cyclopropanation of vinylidenecyclopropanes by dihalocarbenes is described. Reaction of diarylvinylidenecyclopropanes with dibromocarbene and dichlorocarbene excl
- Maeda, Hajime,Hirai, Takayoshi,Sugimoto, Akira,Mizuno, Kazuhiko
-
p. 7700 - 7706
(2007/10/03)
-
- Metal complex electrocatalytic reduction of 1,1-dihalocyclopropanes
-
Catalytic electroreduction of several substituted gem-dihalocyclopropanes was studied in the presence of metal salen-complexes by polarography, cyclic voltammetry, and preparative electrolysis. Monohalocyclopropanes (54-59%) and the corresponding allene (
- Yanilkin,Strunskaya,Nastapova,Maksimyuk,Bredikhina,Sharafutdinova,Bredikhin
-
p. 923 - 928
(2007/10/03)
-
- Bromine-magnesium exchange in gem-dibromocyclopropanes using Grignard reagents
-
Reaction of gem-dibromocyclopropanes with ethylmagnesium bromide at ambient temperature leads to very high yields of allenes; when cyclopropylidene-allene ring opening is suppressed, alternative carbenic products are observed, although other reactions compete. When the reactions are carried out at -60°C, a 1-bromo-1-(bromomagnesio)-cyclopropane is formed which may be trapped by a number of electrophiles.
- Baird, Mark S,Nizovtsev, Alexey V,Bolesov, Ivan G
-
p. 1581 - 1593
(2007/10/03)
-
- Direct transformation of silyl enol ethers into functionalized allenes
-
The first elimination reactions of silyl enol ethers to lithiated allenes are reported. These reactions allow a direct transformation of readily available silyl enol ethers into functionalized allenes. The action of three to four equivalents of lithium di
- Langer, Peter,Doering, Manfred,Seyferth, Dietmar,Goerls, Helmar
-
p. 573 - 584
(2007/10/03)
-
- Unusual regioselectivity of Pd(0)-catalyzed coupling reaction of electron-deficient alkenyl halides with allenic/propargylic zinc reagents. Highly selective synthesis of 6-phenylhex-5-yn-2(or 3)-enoates/enitrile and 4-phenyl-6-substituted-hexa-2,4,5-trienoates
-
The Pd(0)-catalyzed coupling reaction of electron-deficient alkenyl halides with the organozinc formed by the subsequent treatment of 1- phenylalk-1-yne with n-BuLi and ZnBr2 with or without a catalytic amount of HgCl2 was studied. Both the allene-formation- and the alkyne-formation-type coupling reactions were observed with high regio- and stereoselectivity: the reaction of 1-phenylprop-1-yne afforded 6-phenylhex-5-yn-2(or 3)-enoates and -enitriles, while the reaction of 1-phenylhex-1-yne formed 4-phenyl-6- substituted-hexa-2,4,5-trienoates. A plausible explanation for the regioselectivity was discussed. The double bonds in 6-phenylhex-5-yn-2- enoates were prone to migrate to the position conjugated with the carbon- carbon triple bonds to form 6-phenylhex-5-yn-3-enoates at higher temperature. The migration did not occur in absence of an excess amount of allenic/propargylic zinc reagent or at low temperature.
- Ma, Shengming,Zhang, Aibin,Yu, Yihua,Xia, Wei
-
p. 2287 - 2291
(2007/10/03)
-
- Photoinduced skeletal rearrangement of 1,1-diarylspiropentanes
-
The photochemical reactivities of 1,1-diarylspiropentanes 1a-c have been investigated under various photolysis conditions. Upon direct photolysis or acetone-sensitized photolysis, 1 underwent skeletal rearrangement to afford methylidenecyclobutanes 2, 3 and 4. A mechanism involving diradical intermediates has been proposed. Also studied were the photochemical and thermal reactions of the electron donor-acceptor (EDA) complexes of 1 with tetracyanoethylene (TCNE). Photoirradiation of the charge-transfer (CT) absorption bands of the EDA complexes resulted in the skeletal rearrangement of 1 to 2 and 3, with concomitant formation of TCNE adducts 11b,c and 12a-c. The X-ray structure of 11c is reported. A mechanism involving ion radical pairs [1?+, TCNE?-] is proposed for the photoreaction. In contrast, no skeletal rearrangement was observed in the thermal reaction of the EDA complexes although i1b and 11c were produced.
- Takahashi, Yasutake,Ohaku, Hitoshi,Morishima, Shin-Ichi,Suzuki, Takanori,Ikeda, Hiroshi,Miyashi, Tsutomu
-
p. 319 - 325
(2007/10/03)
-
- Methyliodid als Quelle fuer CH2: zwei Wege zur Erzeugnung 1,1-disubstituierter Butatriene in der Koordinationssphaere eines Uebergangsmatalls
-
Stichworte: Allenylidenkomplexe, Butatriene, Isomerisierungen, Rhodiumverbindungen
- Werner, Helmut,Laubender, Matthias,Wiedemann, Ralf,Windmueller, Bettina
-
p. 1330 - 1332
(2007/10/03)
-
- Photoinduced skeletal rearrangement of 1,1-diphenylspiropentanes
-
Photoreactions of 1,1-diphenylspiropentanes have been investigated under various photochemical conditions. The exploratory studies have provided unprecedented examples of photochemically induced skeletal rearrangement of spiropentanes to methylenecyclobutanes.
- Takahashi, Yasutake,Ohaku, Hitoshi,Morishima, Shin-Ichi,Suzuki, Takanori,Miyashi, Tsutomu
-
p. 5207 - 5210
(2007/10/02)
-
- Chiral Carbenoids: Their Formation and Reactions
-
Carbenoids, generated by metalation or halogen-metal exchange reactions, have been prepared from chiral vinyl and cyclopropyl halides.The reactivity and stereochemistry observed in the reaction of these carbenoids has been interpreted as being due to meta
- Topolski, M.,Duraisamy, M.,Rachon, J.,Gawronski, J.,Gawronska, K.,et al.
-
p. 546 - 555
(2007/10/02)
-
- Reaction of Chiral Cyclopropyl Halides with SmI2
-
Reductions of (S)-(+)-1-bromo-1-methyl-2,2-diphenylcyclopropane (7), (S)-(+)-1-bromo-1-(methoxymethyl)-2,2-diphenylcyclopropane (19), and (R)-(-)-1-fluoro-1-iodo-2,2-diphenylcyclopropane (11) with samarium(II) iodide is reported.Evidence for a samarium(III) intermediate in the reaction is presented.
- Walborsky, H. M.,Topolski, Marek
-
p. 370 - 373
(2007/10/02)
-
- 2-Propynylamines from 1,1-Dibromo-1-alkenes
-
Easily accessible 1,1-dibromo-1-alkenes react with primary or secondary amines in a complex series of reactions to give directly N-substituted or N,N-disubstituted (1-Alkyl-1-aryl-2-propynyl)amines 5 in useful yields.This simple method avoids the isolation of intermediates (bromoacetylenes or bromoallenes) and makes a series of 2-propynylamines with an acetylenic hydrogen available.
- Frey, Herbert,Kaupp, Gerd
-
p. 931 - 934
(2007/10/02)
-
- PALLADIUM-CATALYZED REDUCTION OF PROPARGYLIC ACETATES WITH SmI2. A MILD AND CONVENIENT METHOD FOR THE PREPARATION OF ALLENES
-
A highly regioselective reduction of propargylic acetates has been attained by using SmI2 and catalytic Pd(0) in the presence of 2,4-dimethyl-3-pentanol affording various types of allenes in high yields.
- Tabuchi, Takanori,Inanaga, Junji,Yamaguchi, Masaru
-
p. 5237 - 5240
(2007/10/02)
-
- Photolysis of Vinyl Halides. Preferential Formation of Vinyl Cations by Copper(II) Salts
-
Photolysis of vinyl halides in the presence of copper(II) salts in a significant suppression of product formation derived from vinyl radicals.Photolysis of 1,1-diaryl-2-bromopropenes in the presence of copper(II) salts yielded no 1,1-diaryl-2-propenes.Photolysis of other vinyl halides, i.e., 1,1-diaryl-2-iodopropenes, 1,1-diaryl-2-bromoethylenes, and 1-bromo-2-(p-methoxyphenyl)ethylene, also led to a large decrease in the yields of the reduced olefins derived from the vinyl radicals.Copper(II) triflate was found to be more effective for the oxidation of vinyl radicals than copper(II) acetate.These reactions are explained by the intervention of vinylcopper intermediates and the formation of vinyl cations.
- Kitamura, Tsugio,Kobayashi, Shinjiro,Taniguchi, Hiroshi
-
p. 2641 - 2645
(2007/10/02)
-
- CARBENOIDS. METAL ASSISTED IONIZATION
-
Treatment of (S)-(+)-1-chloro-2,2-diphenylcyclopropane with n-butyllithium at -25 deg C yield, inter alia, (R)-(-)-1-n-butyl-2,2diphenylcyclopropane with overall inverted configuration.A metal assisted ionization mechanism is proposed.
- Walborsky,H.M.,Duraisamy,M.
-
p. 2743 - 2746
(2007/10/02)
-
- REACTION OF 2,2-DISUBSTITUTED 1-(DIBROMOMETHYLENE)CYCLOPROPANES WITH METHYLLITHIUM
-
In the reaction of 2,2-disubstituted 1-(dibromomethylene)cyclopropanes with methyllithium 4,4-disubstituted 1-buten-3-ynes and 2,2-disubstituted (1-bromoethylidene)cyclopropanes are formed in ratios which depend on the character of substitution in the cyclopropane ring.
- Kostikov, R. R.,Molchanov, A. P.,Nagi, Sh. M.
-
p. 1291 - 1297
(2007/10/02)
-
- Photochemistry of Vinyl Halides. Vinyl Cation from Photolysis of 1,1-Diaryl-2-halopropenes
-
Irradiation of 1,1-diaryl-2-halopropenes in methanol gave 1,1-diarylpropenes, 1,1-diarylallenes, 1,2-diaryl-1-methoxypropenes, and 9-methoxy-10-methylphenanthrenes.The propenes are derived from vinyl radicals which are generated by homolytic fission of th
- Kitamura, Tsugio,Kobayashi, Shinjiro,Taniguchi, Hiroshi
-
p. 2323 - 2328
(2007/10/02)
-