- A General and Stereospecific Synthesis of Trans Alkenes and Regiospecific Synthesis of Ketones via Stepwise Hydroboration
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The hydroboration of 1-bromo-1-alkynes with alkylbromoboranes (RBHBr*SMe2), conveniently obtained via the controlled hydridation of alkyldibromoboranes (RBBr2*SMe2), followed by treatment with sodium methoxide produces B-(trans-1-alkyl-1-alkenyl)boronate esters that provide the corresponding trans alkenes on protonolysis and ketones on oxidation
- Brown, Herbert C.,Basavaiah, D.,Kulkarni, Surendra U.
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- Single-Electron-Transfer-Induced Coupling of Alkylzinc Reagents with Aryl Iodides
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Alkylzinc reagents prepared from an alkyllithium and zinc iodide were found to undergo coupling with aryl and alkenyl iodides in the presence of LiI in a mixed solvent consisting of THF and diglyme (1:1). Alkyllithiums, prepared by halogen–lithium exchange between an alkyl iodide and tert-butyllithium, are also converted to alkylarenes through alkylzinc reagents.
- Okura, Keisho,Shirakawa, Eiji
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supporting information
p. 3043 - 3046
(2016/07/14)
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- Stereoretentive Pd-catalyzed kumada-corriu couplings of alkenyl halides at room temperature
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Stereoselective palladium-catalyzed Kumada-Corriu reactions of functionalized alkenyl halides and a variety of Grignard reagents, including those bearing β-hydrogen atoms and sensitive functional groups, can be carried out at room temperature using a new combination of reagents.
- Krasovskiy, Arkady L.,Haley, Stephen,Voigtritter, Karl,Lipshutz, Bruce H.
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p. 4066 - 4069
(2014/10/15)
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- Iron thiolate complexes: Efficient catalysts for coupling alkenyl halides with alkyl grignard reagents
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Ironing out the kinks: Efficient new catalytic systems based on iron thiolates are described for the iron-catalyzed cross-coupling of alkyl Grignard reagents with alkenyl halides (see scheme). The reaction is highly chemo- and stereoselective. With this new procedure, the use of N-methylpyrrolidone as a co-solvent is no longer required. Copyright
- Cahiez, Gerard,Gager, Olivier,Buendia, Julien,Patinote, Cindy
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supporting information; experimental part
p. 5860 - 5863
(2012/07/01)
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- Nickel-catalyzed cross-coupling reactions of alkyl aryl sulfides and alkenyl alkyl sulfides with alkyl grignard reagents using (Z)-3,3-dimethyl-1,2- bis(diphenylphosphino)but-1-ene as ligand
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A combination of nickel(II) acetylacetonate and (Z)-3,3-dimethyl-1,2- bis(diphenylphosphino)but-1-ene catalyzes cross-coupling reactions of alkyl aryl sulfides and alkenyl alkyl sulfides with alkyl Grignard reagents. Not only primary but also secondary alkyl Grignard reagents can be employed. Georg Thieme Verlag Stuttgart.
- Kanemura, Shigenari,Kondoh, Azusa,Yorimitsu, Hideki,Oshima, Koichiro
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scheme or table
p. 2659 - 2664
(2009/04/05)
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- Alkynylsilanes as convenient precursors for the stereoselective synthesis of (E)-disubstituted alkenes
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Hydromagnesiation of alkynylsilanes 1 gives (Z)-α-silylvinyl Grignard reagents 2, which are reacted with alkyl iodides or aryl iodides in the presence of Cul or Pd(PPh3)4 catalysts to afford (Z)-1,2-disubstituted vinylsilanes 3 in good yields. Intermediates 3 can undergo a desilylation reaction to give (E)-disubstituted alkenes 4 in high yields.
- Zhao, Hong,Cai, Mingzhong
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p. 608 - 610
(2007/10/03)
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- Synthesis of trisubstituted and tetrasubstituted alkenes via a manganate-induced migration-elimination process
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Preparation of alkenes via a manganate-induced alkylation-elimination sequence was investigated. The reaction of 2-alkoxy-1,1-dibromoalkanes with trialkylmanganates afforded disubstituted or trisubstituted alkenes. Treatment of 2-alkoxy-1,1,1-tribromoalkanes with trialkylmanganates provided trisubstituted or tetrasubstituted alkenes through bromine-metal exchange, transfer of two alkyl groups from manganese to carbon, and successive elimination of metal and the β-alkoxy moieties.
- Kakiya, Hirotada,Shinokubo, Hiroshi,Oshima, Koichiro
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p. 10063 - 10069
(2007/10/03)
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- Cobalt-catalyzed alkenylation of zinc organometallics
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Organozinc halides and diorganozincs undergo cross-coupling reactions with either E- or Z-alkenyl iodides in the presence of catalytic amounts of Co(acac)2 or Co(acac)3 in THF:NMP at 55°C leading to polyfunctional alkenes with retent
- Avedissian, Hovsep,Berillon, Laurent,Cahiez, Gerard,Knochel, Paul
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p. 6163 - 6166
(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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- CATALYTIC HYDROGENATION OF ALKYNES TO CIS-ALKENES ON A MODIFIED BORON-NICKEL CATALYST
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Hydrogenation of alkynes from decyne and dodecyne (C10-C12) with the triple bond at C3, C4, C5, and C6 led to the corresponding alkenes on a boron-nickel catalyst modified by a 1-phenyl-2,3-dimethyl-4-amino-5-pyrazolone (4-aminoantipyrene).The stereospecificity for formation of the cis-alkenes was 95-98percent.
- Siimer, E. Kh.,Petrova, S. S.
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p. 2516 - 2518
(2007/10/02)
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- Vinylic Organoboranes. 6. A General Synthesis of (E)-Disubstituted Alkenes or Ketones via the (E)-(1-Substituted-1-alkenyl)boronic Esters
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Development of a general stereospecific synthesis of (E)-disubstituted alkenes utilizing a variety of hydroborating agents such as monohaloborane, thexylborane, thexylchloroborane, and dibromoborane is discussed.Hydroboration of 1-halo-1-alkynes with dial
- Brown, Herbert C.,Basavaiah, D.,Kulkarni, Surendra U.,Lee, Hsiupu D.,Negishi, Ei-ichi,Katz, Jean-Jacques
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p. 5270 - 5276
(2007/10/02)
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- HOMOALLYLIC SUBSTITUTION REACTIONS OF LITHIUM DIALKYL CUPRATES WITH CYCLOPROPYLCARBINYL HALIDES: MECHANISTIC CONSIDERATIONS
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Highly reactive lithium dialkyl cuprates and 1-bromo-1-cyclopropylalkanes, 4, react to give good yields of the homoallylic substitution product, 6.Less reactive organocuprates react with 4 to give mixtures of 6 and the direct substitution product 7.These results are consistent with a copper(I) radical intermediate which undergoes facile rearrangement prior to reductive coupling.
- Hrubiec, Robert T.,Smith, Michael B.
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p. 1457 - 1468
(2007/10/02)
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- A General Synthesis of B-(cis-1-bromo-1-alkenyl)dialkylboranes. Valuable Intermediates for the Synthesis of Ketones, Trans Alkenes, and Trisubstituted Alkenes
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Dialkylboranes, generated in situ via hydridation of dialkylhaloboranes, hydroborate 1-bromo-1-alkynes to provide cleanly B-(cis-1-bromo-1-alkenyl)dialkylboranes.Treatment of these intermediates with sodium methoxide results in the migration of one of the alkyl groups on boron to the adjacent carbon, displacing the bromine, providing B-(trans-1-alkyl-alkenyl)alkylborinate esters.These intermediates provide ketones on oxidation, stereospecific trans alkenes on protonolysis, and trisubstituted alkenes on iodination, all in high yields.
- Brown, Herbert C.,Basavaiah, D.
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p. 754 - 756
(2007/10/02)
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