- METHODS OF BORYLATION AND USES THEREOF
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The present invention relates, in general terms, to methods of borylation and uses thereof. In particular, the present invention provides a method of borylating an alkene compound by contacting the compound with a boron compound, a Fe pre-catalyst and a protic additive. The borylation occurs at a vicinal (β) position to an electron donating or electron withdrawing moiety of the compound.
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Page/Page column 61-62
(2021/04/30)
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- Visible-Light Controlled Divergent Catalysis Using a Bench-Stable Cobalt(I) Hydride Complex
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While the use of visible light in conjunction with transition metal catalysis offers powerful opportunities to switch between on/-off states of catalytic activity, the next frontier would be the ability to switch the actual function of the catalyst and resulting products. Here we report such an example of multi-dimensional catalysis. Featuring an easily prepared, bench-stable cobalt(I) hydride complex in conjunction with pinacolborane, we can switch the reaction outcome between two widely employed transformations, olefin migration and hydroboration, with visible light as the trigger.
- Beltran, Frédéric,Bergamaschi, Enrico,Teskey, Christopher J.
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supporting information
p. 5180 - 5184
(2020/04/22)
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- Iron-Catalyzed Tunable and Site-Selective Olefin Transposition
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The catalytic isomerization of C-C double bonds is an indispensable chemical transformation used to deliver higher-value analogues and has important utility in the chemical industry. Notwithstanding the advances reported in this field, there is compelling demand for a general catalytic solution that enables precise control of the C═C bond migration position, in both cyclic and acyclic systems, to furnish disubstituted and trisubstituted alkenes. Here, we show that catalytic amounts of an appropriate earth-abundant iron-based complex, a base and a boryl compound, promote efficient and controllable alkene transposition. Mechanistic investigations reveal that these processes likely involve in situ formation of an iron-hydride species which promotes olefin isomerization through sequential olefin insertion/β-hydride elimination. Through this strategy, regiodivergent access to different products from one substrate can be facilitated, isomeric olefin mixtures commonly found in petroleum-derived feedstock can be transformed to a single alkene product, and unsaturated moieties embedded within linear and heterocyclic biologically active entities can be obtained.
- Yu, Xiaolong,Zhao, Haonan,Li, Ping,Koh, Ming Joo
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supporting information
p. 18223 - 18230
(2020/12/04)
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- An alternative mechanism for the cobalt-catalyzed isomerization of terminal alkenes to (Z)-2-alkenes
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The cobalt-catalyzed selective isomerization of terminal alkenes to the thermodynamically less-stable (Z)-2-alkenes at ambient temperatures takes place by a new mechanism involving the transfer of a hydrogen atom from a Ph2PH ligand to the starting material and the formation of a phosphenium complex, which recycles the Ph2PH complex through a 1,2-H shift.
- Schmidt, Anastasia,N??dling, Alexander R.,Hilt, Gerhard
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supporting information
p. 801 - 804
(2015/03/04)
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- Double-Bond Isomerization: Highly Reactive Nickel Catalyst Applied in the Synthesis of the Pheromone (9 Z,12 Z)-Tetradeca-9,12-dienyl Acetate
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A highly reactive nickel catalyst comprising NiCl2(dppp) or NiCl2(dppe) with zinc powder, ZnI2 and Ph2PH, was applied in the isomerization of terminal alkenes to Z-2-alkenes. The double-bond geometry of the 2-alkene can be controlled via the reaction temperature to yield the 2-Z-alkenes in excellent yields and high Z-selectivities. The formation of other constitutional isomers, such as 3-alkenes, is suppressed on the basis of the proposed mechanism via a 1,2-hydride shift from the metal to the Ph2P ligand. The nickel-catalyzed isomerization reaction was then applied in the synthesis of (9Z,12Z)-tetradeca-9,12-dienyl acetate, a pheromone with a 2Z,5Z-diene subunit.
- Weber, Felicia,Schmidt, Anastasia,R?se, Philipp,Fischer, Michel,Burghaus, Olaf,Hilt, Gerhard
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supporting information
p. 2952 - 2955
(2015/06/30)
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- Palladium-catalyzed asymmetric silaboration of allenes
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An enantioselective silaboration of allenes was achieved using an achiral silylborane in the presence of a palladium catalyst bearing a chiral monodentate phosphine ligand. (R)-2-Bis(3,5-dimethylphenyl)phosphino-1,1-binaphthyl gave the highest enantiosele
- Ohmura, Toshimichi,Taniguchi, Hiroki,Suginome, Michinori
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p. 13682 - 13683
(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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- Hindered organoboron groups in organic chemistry. 25. The condensation of aliphatic aldehydes with dimesitylboryl stabilised carbanions to give alkenes
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In the presence of protic acids the condensation of aliphatic aldehydes with dimesitylboryl stabilised carbanions results in alkenes. In the presence of strong acids such as HCl or CF3SO3H, the products contain > 90% of E-alkenes in all cases tried. When acetic acid is used, the Z-alkenes may result predominantly, particularly in the cases of R(S)CHO and R(t)CHO.
- Pelter,Smith,Elgendy
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p. 7119 - 7132
(2007/10/02)
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- A Bridged Tetrahydrophosphole Ylide Derived from 9-Phenylphosphabicyclononane: A Reagent for E-Selective Wittig Reactions
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The bicyclic ylide 4 reacts with aldehydes to afford the E-alkenes.Selectivity is 94 - 6percent E for unbranched aldehydes, but the selectivity decreases with increasing α-branching.Ylide 4 is the first E-selective, nonstabilized ylide that allows efficient utilization of the P-alkyl substituent.
- Vedejs, E.,Peterson, M. J.
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p. 1985 - 1986
(2007/10/02)
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- Stereoselectivity of the Thermally Initiated Free-Radical Chain Addition of Cyclohexane to 1-Alkynes
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Alkanes can be added to alkynes in a thermally initiated free-radical chain reaction ("ane reaction").The addition of cyclohexane to 1-alkynes 1a-l yields a mixture of (Z)- and (E)-2-cyclohexyl-1-alkenes 3a-l.An essential step in this reaction is the addi
- Metzger, Juergen O.,Blumenstein, Michael
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p. 2493 - 2500
(2007/10/02)
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- A New Synthesis of (E)-1-Alkyl-1-trimethylsilylpropenes via Hydroboration of 3-Chloro-1-trimethylsilylpropyne with Dialkylboranes
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The successive treatment of 3-chloro-1-trimethylsilylpropyne with dialkylboranes and aqueous sodium hydroxide provided (E)-1-alkyl-1-trimethylsilylpropenes whose alkyl groups were derived from a terminal or internal alkene via dialkylboranes.
- Hoshi, Masayuki,Masuda, Yuzuru,Arase, Akira
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p. 251 - 254
(2007/10/02)
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- Novel ortho-Alkoxy-Substituted Phosphorus Ylides and Their Stereoselectivity in Wittig Reactions
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The stereochemistry of the reactions between tris(2-methoxymethoxypheny)phosphonioethanide (1f), -butanide (2f), and -phenyl-methanide (3f) and a variety of aldehydes was investigated.Ylides having a β-unbranched aliphatic sidechain, such as 2f, and saturated straight-chain aldehydes give olefins with unprecedented cis-selectivity (cis/trans ca. 200:1).
- Jeganathan, Suruliappa,Tsukamoto, Masamitsu,Schlosser, Manfred
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p. 109 - 111
(2007/10/02)
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- HINDERED ORGANOBORON GROUPS IN ORGANIC SYNTHESIS. 14. STEREOSELECTIVE SYNTHESIS OF ALKENES BY THE BORON-WITTIG REACTION USING ALIPHATIC ALDEHYDES
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In the presence of HX, carbanions Mes2BCHLiR1 react with aliphatic aldehydes to give alkenes.The stereochemistry of product alkene depends upon the nature of HX.
- Pelter, Andrew,Smith, Keith,Elgendy, Said,Rowlands, Martin
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p. 5647 - 5650
(2007/10/02)
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- HINDERED ORGANOBORON GROUPS IN ORGANIC SYNTHESIS. 13. THE DIRECT PRODUCTION OF KETONES FROM ALIPHATIC ALDEHYDES BY A UNIQUE VARIANT OF THE BORON-WITTIG REACTION
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In the presence of trifluoroacetic anhydride or N-chlorosuccinimide, aliphatic aldehydes react with dimesitylboron stabilised carbanions to give after work up, the corresponding ketones, a process wich is unique among Wittig type reactions.Yields of ketones are satisfactory in all cases except those involving the anion derived from the parent compound dimesitylmethylborane, wich give the corresponding alkenes.
- Pelter, Andrew,Smith, Keith,Elgendy, Said,Rowlands, Martin
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p. 5643 - 5646
(2007/10/02)
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- DBP YLDES: WITTIG REAGENTS FOR SYNTHESIS OF E-ALKENES FROM ALDEHYDES
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Phosphorus yldes based on the dibenzophosphole (DPP) ring system convert aldehydes into trans-disubstituted oxaphosphetanes with good to excellent selectivity.Decomposition at 70-110 deg C affords alkenes with E:Z rations from 6:1 to > 100:1.
- Vedejs, E.,Marth, C.
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p. 3445 - 3448
(2007/10/02)
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- The Stereocontrolled Horner-Wittig Reaction: Synthesis of Disubstituted Alkenes
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Addition of the lithium derivatives of phosphine oxides Ph2P(O)CH2R1 to aldehydes gives erythro adducts (11) with good stereoselectivity.Reduction of α-diphenylphosphinoyl ketones (12) gives threo adducts (11) with even better stereoselectivity.Purification by flash chromatography and/or crystallisation followed by elimination of Ph2PO2 gives pure Z- or E-alkenes with high material conversion.Explanations are offered for the stereoselectivities, conditions defined for full stereochemical control, and guidelines suggested for approaches to a given alkene.
- Buss, Antony D.,Warren, Stuart
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p. 2307 - 2326
(2007/10/02)
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- CIS-OLEFINS FROM THE HORNER-WITTIG REACTION; ORIGIN AND OPTIMISATION OF STEREOCHEMISTRY
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Conditions are described to produce high yields of erythro Horner-Wittig intermediates: stereospecific elimination gives cis-alkenes.
- Buss, Antony D.,Warren, Stuart
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p. 3931 - 3934
(2007/10/02)
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