- Cobalt-catalyzed allylic substitution reaction of allylic ethers with phenyl and trimethylsilylmethyl grignard reagents
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Treatment of cinnamyl methyl ether with phenylmagnesium bromide in ether in the presence of CoCl2[1,5-bis(diphenylphosphino)pentane] affords 1,3-diphenylpropene in good yield. Similar allylic substitution reaction with trimethylsilylmethylmagne
- Mizutani, Keiya,Yorimitsu, Hideki,Oshima, Koichiro
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- γ-1,4 Addition of substituted methoxyallylcopper reagents to methylvinylketone
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Methoxyallylcopper reagents substituted in α and/or β position of methoxy group reacted regiospecifically with MVK to give γ-1,4 adducts, i.e. ketoenolethers, γ substituted methoxyallylcopper reagents gave mixtures of γ-1,4 and α-1,4 adducts.
- Berrien, Jean-Francois,Raymond, Marie-Noelle,Zaari, Fatima,Moskowitz, Henri,Mayrargue, Joelle
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Read Online
- Nickel-Mediated Enantiospecific Silylation via Benzylic C-OMe Bond Cleavage
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Benzylic stereocenters are found in bioactive and drug molecules, as enantiopure benzylic alcohols have been used to build such a stereogenic center, but are limited to the construction of a C-C bond. Silylation of alkyl alcohols has the potential to build bioactive molecules and building blocks; however, the development of such a process is challenging and unknown. Herein, we describe an unprecedented AgF-assisted nickel catalysis in the enantiospecific silylation of benzylic ethers.
- Balakrishnan, Venkadesh,Murugesan, Vetrivelan,Chindan, Bincy,Rasappan, Ramesh
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supporting information
p. 1333 - 1338
(2021/02/20)
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- Oxoammonium-Mediated Allylsilane–Ether Coupling Reaction
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A new C(sp3)?H functionalization reaction consisting of the oxidative α-allylation of allyl- and benzyl- methyl ethers has been developed. The C?C coupling could be carried out under mild conditions thanks to the use of cheap and green oxoammonium salts. The scope of the reaction was studied over 27 examples, considering the nature of the substituents on the two coupling partners.
- Carlet, Federica,Bertarini, Greta,Broggini, Gianluigi,Pradal, Alexandre,Poli, Giovanni
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supporting information
p. 2162 - 2168
(2021/04/02)
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- Water promoted allylic nucleophilic substitution reactions of (: E)-1,3 diphenylallyl acetate
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A transition metal free, water based, greener protocol for the allylic alkylation, allylic amination, O-allylation of (E)-1,3-diphenylallyl acetate is described. The developed methodology is applicable for a wide range of nucleophiles furnishing excellent yields of corresponding products up to 87% under mild reaction conditions. A distinct effect of water and base is explored for allylic nucleophilic substitution reactions of (E)-1,3-diphenylallyl acetate.
- Ghorpade, Seema A.,Sawant, Dinesh N.,Makki, Arwa,Sekar, Nagaiyan,Eppinger, J?rg
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supporting information
p. 425 - 430
(2018/02/07)
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- Stereoselective synthesis of allyl ethers using α,β-unsaturated acylsilanes
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The reaction behavior of silylvinylmethanols with acid catalysts was investigated. The starting silylvinylmethanols 2 were prepared by the reaction of the corresponding α,β-unsaturated acylsilanes 1 with organocerium reagents. The reaction of 2 with TsOH
- Honda, Mitsunori,Takatera, Takehide,Ui, Ryosuke,Kunimoto, Ko-Ki,Segi, Masahito
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p. 864 - 869
(2017/02/18)
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- TRACELESS DIRECTING GROUPS IN RADICAL CASCADES: FROM OLIGOALKYNES TO FUSED HELICENES WITHOUT TETHERED INITATORS
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The present disclosure is directed to a traceless directing group in a radical cascade. The chemo- and regioselectivity of the initial attack in skipped oligoalkynes is controlled by a propargyl alkoxy moiety. Radical translocations lead to the boomerang return of radical center to the site of initial attack where it assists to the elimination of the directing functionality via β-scission in the last step of the cascade. In some aspects, the reaction of the present invention is catalyzed by a stannane moiety, which allows further via facile reactions with electrophiles as well as Stille and Suzuki cross-coupling reactions. This selective radical transformation opens a new approach for the controlled transformation of skipped oligoalkynes into polycyclic ribbons of tunable dimensions.
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Paragraph 0348; 0349
(2016/06/13)
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- Traceless directing groups in radical cascades: From oligoalkynes to fused helicenes without tethered initiators
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We report the first example of a traceless directing group in a radical cascade. The chemo- and regioselectivity of the initial attack in skipped oligoalkynes is controlled by propargyl OR moiety. Radical translocations lead to the boomerang return of the radical center to the site of initial attack where it assists the elimination of the directing functionality via β-scission in the last step of the cascade. The Bu3Sn moiety continues further via facile reactions with electrophiles as well as Stille and Suzuki cross-coupling reactions. This selective radical transformation opens a new approach for the controlled transformation of skipped oligoalkynes into polycyclic ribbons of tunable dimensions. (Chemical Equation Presented).
- Pati, Kamalkishore,Gomes, Gabriel Dos Passos,Harris, Trevor,Hughes, Audrey,Phan, Hoa,Banerjee, Tanmay,Hanson, Kenneth,Alabugin, Igor V.
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supporting information
p. 1165 - 1180
(2015/02/05)
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- Oxidative ether formation between 1,3-Diarylpropene and alcohol promoted by N-hydroxyphthalimide/O2
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An oxidative ether formation between 1,3-diarylpropene and alcohol is catalysed by CuBr/NiCl2 using N-hydroxyphthalimide/O2.
- Cheng, Dongping,Sun, Ruirui,Cui, Wei,Yan, Jizhong
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p. 420 - 422
(2014/08/05)
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- A highly efficient, metal-free and convenient diarylallyl ether/ thioether formation via oxidative c-h activation
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A metal free highly efficient and concise oxidative-coupling ether formation between 1,3-diarylallylic sp3 C-H and aliphatic alcohols promoted by 2,3-dichloro-5,6-dicyanoquinone (DDQ) is reported. This system is also applied to form C-S bonds f
- Li, Yan,Bao, Weiliang
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supporting information; experimental part
p. 865 - 868
(2009/11/30)
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- Applications of lanthanide trichloride hydrates prepared from mischmetall in Luche-type reduction
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An inexpensive alloy of light lanthanides, called Mischmetall, has been used in the preparation of a mixture of lanthanide trichloride hydrates. The use of this new type of material is described in Luche-type reductions. Georg Thieme Verlag Stuttgart.
- Lannou, Marie-Isabelle,Hélion, Florence,Namy, Jean-Louis
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p. 2707 - 2710
(2008/02/12)
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- Cobalt- and rhodium-catalyzed cross-coupling reaction of allylic ethers and halides with organometallic reagents
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Reactions of 2-alkenyl methyl ether with phenyl, trimethylsilylmethyl, and allyl Grignard reagents in the presence of cobalt(II) complexes are discussed. The success of the reactions heavily depends on the combination of the substrate, ligand, and Grignard reagent. In the reaction of cinnamyl methyl ether, the formation of the linear coupling products predominates over that of the relevant branched products. In the cobalt-catalyzed allylation of allylic ethers, addition of a diphosphine ligand can change the regioselectivity, mainly providing the corresponding branched products. Rhodium complexes catalyze the reactions of allylic ethers and halides with allylmagnesium chloride and allylzinc bromide, respectively, in which the branched coupling product is the major product.
- Yasui, Hiroto,Mizutani, Keiya,Yorimitsu, Hideki,Oshima, Koichiro
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p. 1410 - 1415
(2007/10/03)
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- Water-mediated transition-metal-free Tsuji-Trost-type reaction
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The treatment of 1-acetoxy-1,3-diphenylpropene (1) by C-, O-, S- and N-nucleophiles in basic aqueous media produced the corresponding substitution products in the absence of a transition-metal catalyst. Mechanistic studies, using (S)-1 and p-MeC6/su
- Chevrin, Carole,Le Bras, Jean,Hénin, Fran?oise,Muzart, Jacques
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p. 8099 - 8102
(2007/10/03)
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- A non-cope among the cope rearrangements of 1,3,4,6-tetraphenylhexa-1,5- dienes
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The set of 1,3,4,6-tetraphenylhexa-1,5-dienes (1) represents a perturbation of Cope's rearrangement by four radical-stabilizing phenyl groups all positioned to drive the transition region toward the homolytic- colligative end of the mechanistic spectrum. The appearance of (Z)-isomers being suppressed thermodynamically by a steric interaction of +2.6 kcal mol- 1 per cis double bond, an equilibration that is stereochemically not of any Cope type, emerges as the predominant reaction. It is an interconversion of rac-(E,E)-1 and meso-(E,E)-1 (48:52; 77.3-115.3 °C) with the following values of the enthalpy, entropy, and volume of activation: ΔH(+) = 30.7 ± 0.2 kcal mol-1, ΔS(+) = +2.1 ± 0.4 cal mol-1 K-1, and ΔV(+) = +13.5 ± 0.1 cm-3 mol-1, respectively. Structures have been established by X- ray crystallographic analysis; a possible relationship between dihedral angle and bond lengths in the styrene portions is proposed. The entropy of activation is incompatible with a chair or boat Cope rearrangement; the volume of activation is neither low enough for a pericyclic Cope ('concerted') mechanism nor high enough for a homolytic-colligative mechanism involving full dissociation as the rate-determining step. Trapping and a crossover experiment give some but only partial support to the intermediacy of free radicals. At higher temperatures, however, electron spin resonance experiments demonstrate an equilibrium with kinetically free (E,E)-1,3- diphenylallyl radicals. These observations are rationalized in terms of geometric reorganization within the confines of a 'cage'. Resolution by chiral chromatography of rac-(E,E)-1 allows recognition of a fast racemization (40-65 °C), of which ΔH(+) (21.3 ± 0.1 kcal mol-1), DS(+) (-13.2 ± 0.3 cal mol-1 K-1), and ΔV(+) (-7.4 ± 0.4 cm-3 mol-1) are consistent with a pericyclic Cope rearrangement. Enriched (Z)-isomers undergo Cope rearrangements in accord with the known influence of axiality and the chair/boat alternative on the energy of the transition region.
- Doering,Birladeanu, Ludmila,Sarma, Keshab,Blaschke,Scheidemantel, Ursula,Boese,Benet-Bucholz, Jordi,Klaerner,Gehrke, Jan-Stephan,Zimny, Bernd Ulrich,Sustmann,Korth, Hans-Gert
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p. 193 - 203
(2007/10/03)
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- METHOXYCHLORINATION AND DIMETHOXYLATION OF ALKENES. THE REACTIONS OF SUBSTITUTED STYRENES WITH PHENYLSELENENYL CHLORIDE IN METHANOL
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The addition of PhSeCl to α- and β-substituted styrenes in methanol is regio- and stereospecific and affords the products of methoxyselenenylation.These compounds further react with PhSeCl to give the deselenenylation products.In the case of α-substituted styrenes, 1-methoxy, 2-chloroalkanes are produced, whereas with β-substituted styrenes the major reaction products are the 1,2-dimethoxyalkanes and the 2,2-dimethoxyalkanes in which phenyl migration has occured.It is shown that these reactions proceed through the intermediate formation of the alkyl phenylselenium dichlorides, PhCR(OMe)CHR1SeCl2Ph, which evolve with different mechanisms depending on the structure of the starting alkenes.
- Tiecco, Marcello,Testaferri, Lorenzo,Tingoli, Marco,Chianelli, Donatella,Bartoli, Donatella
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p. 2261 - 2272
(2007/10/02)
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