- Transborylation of alkenylboranes with diboranes
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Exchange of boryl moieties between alkenylboranes and diboron reagents has been postulated as a stereospecific cross-metathesis pathway with concomitant formation of mixed diboron reagents. DFT calculations propose a mechanism for the stereocontrolled C(sp2)-B/B′-B′ cross-metathesis with both symmetric and non-symmetric diboron reagents. This journal is
- Bru, Gerard,Carbó, Jorge J.,Dominguez-Molano, Paula,Fernández, Elena,Maza, Ricardo J.,Salvado, Oriol
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supporting information
p. 13361 - 13364
(2021/12/17)
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- Electrochemical Hydroboration of Alkynes
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Herein we reported the electrochemical hydroboration of alkynes by using B2Pin2 as the boron source. This unprecedented reaction manifold was applied to a broad range of alkynes, giving the hydroboration products in good to excellent yields without the need of a metal catalyst or a hydride source. This transformation relied on the possible electrochemical oxidation of an in situ formed borate. This anodic oxidation performed in an undivided cell allowed the formation of a putative boryl radical, which reacted on the alkyne.
- Aelterman, Maude,Jubault, Philippe,Poisson, Thomas,Sayes, Morgane
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supporting information
p. 8277 - 8282
(2021/05/27)
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- Cs4B4O3F10: First Fluorooxoborate with [BF4] Involving Heteroanionic Units and Extremely Low Melting Point
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Herein, a new congruently melting mixed-anion compound Cs4B4O3F10 has been characterized as the first fluorooxoborate with [BF4] involving heteroanionic units. Compound Cs4B4O3F10 possesses two highly fluorinated anionic clusters and therefore its formula can be expressed as Cs3(B3O3F6) ? Cs(BF4). The influence of [BF4] units on micro-symmetry and structural evolution was discussed based on the parent compound. More importantly, Cs4B4O3F10 shows the lowest melting point among all the available borates and thus sets a new record for such system. This work is of great significance to enrich and tailor the structure of borates using perfluorinated [BF4] units.
- Xia, Ming,Mutailipu, Miriding,Li, Fuming,Yang, Zhihua,Pan, Shilie
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supporting information
p. 9753 - 9757
(2021/05/27)
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- Catalyst-free and solvent-free hydroboration of alkynes
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The hydroboration of alkynes with pinacolborane (HBpin) under catalyst- and solvent-free conditions was demonstrated. Various alkynes were smoothly converted into alkenyl boronate esters in good to excellent yields at 110 °C. The gram-scale hydroboration
- Jaladi, Ashok Kumar,Choi, Hyeon Seong,An, Duk Keun
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p. 13626 - 13632
(2020/09/07)
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- Solvent- and metal-free hydroboration of alkynes under microwave irradiation
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Boronic esters are versatile building blocks extensively used in organic chemistry and essential to a variety of coupling reactions. In this work, the hydroboration reactions of alkynes were performed without metal catalysts using concomitant microwave ir
- Arnaud, Alexandre,Doléans-Jordheim, Anne,Gioia, Bruna,Radix, Sylvie,Rocheblave, Luc,Walchshofer, Nadia
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- Stereoselective Synthesis of Trisubstituted Vinylboronates from Ketone Enolates Triggered by 1,3-Metalate Rearrangement of Lithium Enolates
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An unprecedented stereoselective synthesis of trisubstituted vinylboronates is reported to proceed by direct borylation of lithium ketone enolates under transition-metal-free conditions. The stereospecific C?O borylation of lithium enolates was triggered by a carbonyl-induced 1,3-metalate rearrangement via a C-bound boron enolate. DFT calculations and control experiments revealed that the stereoselectivity is controlled by sterics. A variety of stereospecific trisubstituted vinylboronates, together with several tetrasubstituted vinylboronates, were conveniently synthesized with the newly developed methodology. Based on the transformation of stereospecific vinylboronate, a single isomer of Dienestrol was efficiently obtained.
- Hu, Yue,Sun, Wei,Zhang, Tao,Xu, Nuo,Xu, Jianeng,Lan, Yu,Liu, Chao
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p. 15813 - 15818
(2019/10/28)
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- Migratory Arylboration of Unactivated Alkenes Enabled by Nickel Catalysis
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An unprecedented arylboration of unactivated terminal alkenes, featuring 1,n-regioselectivity, has been achieved by nickel catalysis. The nitrogen-based ligand plays an essential role in the success of this three-component reaction. This transformation displays good regioselectivity and excellent functional-group tolerance. In addition, the incorporation of a boron group into the products provides substantial opportunities for further transformations. Also demonstrated is that the products can be readily transformed into pharmaceutically relevant molecules. Unexpectedly, preliminary mechanistic studies indicate that although the metal migration favors the α-position of boron, selective and decisive bond formation is favored at the benzylic position.
- Wang, Wang,Ding, Chao,Li, Yangyang,Li, Zheqi,Li, Yuqiang,Peng, Long,Yin, Guoyin
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supporting information
p. 4612 - 4616
(2019/03/13)
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- Silver-Catalyzed anti-Markovnikov Hydroboration of C-C Multiple Bonds
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A simple silver salt (AgOAc)-catalyzed anti-Markovnikov-selective hydroboration of alkenes, 1,3-dienes, and alkynes with pinacolborane (HBpin) has been described. This strategy provides an efficient and practical method to access various alkyl-, allyl-, a
- Wang, Yan,Guan, Rui,Sivaguru, Paramasivam,Cong, Xuefeng,Bi, Xihe
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supporting information
p. 4035 - 4038
(2019/06/14)
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- Lithium diisobutyl-: Tert-butoxyaluminum hydride (LDBBA) catalyzed hydroboration of alkynes and imines with pinacolborane
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Lithium diisobutyl-tert-butoxyaluminum hydride (LDBBA)-catalyzed hydroboration of alkynes with pinacolborane (HBpin) was demonstrated. The hydroboration proceeded more efficiently with LDBBA than with other aluminum hydrides and afforded alkenyl boronates in moderate to good yields. In addition, high-yielding LDBBA-catalyzed hydroboration of imines was achieved. The coordination of anionic aluminate with lithium enables effective hydride transfer for hydroboration.
- Jaladi, Ashok Kumar,Kim, Hanbi,Lee, Ji Hye,Shin, Won Kyu,Hwang, Hyonseok,An, Duk Keun
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p. 16524 - 16529
(2019/11/11)
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- Borane-Catalysed Hydroboration of Alkynes and Alkenes
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Simple, commercially available borane adducts, H 3 B·THF and H 3 B·SMe 2, have been used to catalyse the hydroboration of alkynes and alkenes with pinacolborane to give the alkenyl and alkyl boronic esters, respectively. A
- Ang, Nate W. J.,Buettner, Cornelia S.,Docherty, Scott,Bismuto, Alessandro,Carney, Jonathan R.,Docherty, Jamie H.,Cowley, Michael J.,Thomas, Stephen P.
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p. 803 - 808
(2018/02/10)
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- Electrophilic borylation of terminal alkenes with BBr3/2,6-disubstituted pyridines
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A variety of terminal alkenes, as well as heteroaromatic compounds, are borylated by the combined use of BBr3/2,6-dichloropyridine (B3) or BBr3/2,6-lutidine (B5). α,α-Diarylalkenes prefer the former reagent combination, while other alkenes prefer the latter. Mechanistic considerations strongly suggest that the former and latter reactions proceed through electrophilic substitution reactions with BBr3 and [BBr2·B5]+BBr4-, respectively.
- Tanaka, Shinya,Saito, Yuki,Yamamoto, Takaya,Hattori, Tetsutaro
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supporting information
p. 1828 - 1831
(2018/04/14)
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- Stable, Yet Highly Reactive Nonclassical Iron(II) Polyhydride Pincer Complexes: Z-Selective Dimerization and Hydroboration of Terminal Alkynes
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The synthesis, characterization, and catalytic activity of nonclassical iron(II) polyhydride complexes containing tridentate PNP pincer-type ligands is described. These compounds of the general formula [Fe(PNP)(H)2(η2-H2)]
- Gorgas, Nikolaus,Alves, Luis G.,St?ger, Berthold,Martins, Ana M.,Veiros, Luis F.,Kirchner, Karl
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supporting information
p. 8130 - 8133
(2017/06/27)
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- Transition-metal-free PhI(OAc)2-promoted highly selective hydroboration of terminal alkynes under air
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A new transition-metal-free PhI(OAc)2-promoted hydroboration reaction of terminal alkynes with bis(pinacolato)diboron has been developed at room temperature under air. A series of vinyl boronates could be conveniently and efficiently obtained i
- Chen, Suyuan,Yang, Lu,Yi, Dong,Fu, Qiang,Zhang, Zhijie,Liang, Wu,Zhang, Qiang,Ji, Jianxin,Wei, Wei
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p. 26070 - 26073
(2017/07/07)
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- Conjunctive functionalization of vinyl boronate complexes with electrophiles: A diastereoselective three-component coupling
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A method for the conjunctive functionalization of vinyl boronate complexes with electrophiles is described. The overall process represents a three-component coupling between a vinyl boronic ester, carbon nucleophile and an electrophile, thus affording complex multifunctionalized products from simple starting materials. The diastereoselectivity (syn or anti) of this process is strongly dependent upon the nature of the electrophile.
- Armstrong, Roly J.,Sandford, Christopher,García-Ruiz, Cristina,Aggarwal, Varinder K.
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supporting information
p. 4922 - 4925
(2017/07/11)
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- Hydroboration of Alkynes Catalyzed by Pyrrolide-Based PNP Pincer-Iron Complexes
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To utilize iron complexes as catalysts, the application of a well-designed ligand is critical to control the reactivity of the iron center. Recently, our group has succeeded in the synthesis of iron complexes bearing a pyrrolide-based PNP pincer ligand an
- Nakajima, Kazunari,Kato, Takeru,Nishibayashi, Yoshiaki
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supporting information
p. 4323 - 4326
(2017/08/23)
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- (CAAC)CuX-catalyzed hydroboration of terminal alkynes with pinacolborane directed by the X-ligand
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When X is a basic ligand (CAAC)CuX complexes [CAAC?=?cyclic (alkyl) (amino)carbene] selectively promote the (E)-β-hydroboration of terminal alkynes with pinacolborane instead of the dehydrogenative borylation observed with weakly nucleophilic X ligand. This methodology is applicable to a variety of terminal alkynes. Deuterium labeling experiments coupled with stoichiometric reactions give evidence towards a plausible mechanism involving a σ-mono (copper)acetylide complex.
- Romero, Erik A.,Jazzar, Rodolphe,Bertrand, Guy
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supporting information
p. 11 - 13
(2017/02/18)
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- Stereospecific Allylic Functionalization: The Reactions of Allylboronate Complexes with Electrophiles
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Allylboronic esters react readily with carbonyls and imines (π-electrophiles), but are unreactive toward a range of other electrophiles. By addition of an aryllithium, the corresponding allylboronate complexes display enhanced nucleophilicity, enabling addition to a range of electrophiles (tropylium, benzodithiolylium, activated pyridines, Eschenmoser's salt, Togni's reagent, Selectfluor, diisopropyl azodicarboxylate (DIAD), MeSX) in high regio- and stereocontrol. This protocol provides access to key new functionalities, including quaternary stereogenic centers bearing moieties such as fluorine and the trifluoromethyl group. The allylboronate complexes were determined to be 7 to 10 orders of magnitude more reactive than the parent boronic ester.
- García-Ruiz, Cristina,Chen, Jack L.-Y.,Sandford, Christopher,Feeney, Kathryn,Lorenzo, Paula,Berionni, Guillaume,Mayr, Herbert,Aggarwal, Varinder K.
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supporting information
p. 15324 - 15327
(2017/11/06)
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- Direct synthesis of alkenyl boronic esters from unfunctionalized alkenes: A boryl-heck reaction
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We report the first example of a boryl-Heck reaction using an electrophilic boron reagent. This palladium-catalyzed process allows for the conversion of terminal alkenes to trans-alkenyl boronic esters using commercially available catecholchloroborane (catBCl). In situ transesterification allows for rapid access to a variety of boronic esters, amides, and other alkenyl boron adducts.
- Reid, William B.,Spillane, Jesse J.,Krause, Sarah B.,Watson, Donald A.
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supporting information
p. 5539 - 5542
(2016/05/24)
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- Pd-catalyzed three-component reaction of 3-(Pinacolatoboryl)ally acetates, aldehydes, and organoboranes: A new entry to stereoselective synthesis of (Z)- anti -homoallylic alcohols
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The Pd-catalyzed three-component reaction of 3-(pinacolatoboryl)allyl acetates, aldehydes, and organoboranes is described. The reaction is initiated by the formation of an allylic gem-palladium/boryl intermediate, which then undergoes allylation of aldehydes by allylboronates followed by a coupling reaction of in situ generated (Z)-vinylpalladium acetates with organoboranes to provide the (Z)-anti-homoallylic alcohols with high levels of diastereoselectivity and alkene stereocontrol.
- Horino, Yoshikazu,Aimono, Ataru,Abe, Hitoshi
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supporting information
p. 2824 - 2827
(2015/06/16)
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- Rhodium-catalyzed dehydrogenative borylation of aliphatic terminal alkenes with pinacolborane
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Aliphatic terminal alkenes react with pinacolborane at ambient temperature to afford dehydrogenative borylation compounds as the major product when iPr-Foxap is used as the ligand with cationic rhodium(I) in the presence of norbornene, which acts as the s
- Morimoto, Masao,Miura, Tomoya,Murakami, Masahiro
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supporting information
p. 12659 - 12663
(2015/10/28)
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- An Umpolung Approach to Alkene Carboamination: Palladium Catalyzed 1,2-Amino-Acylation, -Carboxylation, -Arylation, -Vinylation, and -Alkynylation
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Conventional approaches to Pd-catalyzed alkene 1,2-carboamination rely upon the combination of a nucleophilic nitrogen-based component and an internal C-based or external oxidant. In this study, we outline an umpolung approach, which is triggered by oxidative initiation at an electrophilic N-based component and employs "standard" organometallic nucleophiles to introduce the new carbon-based fragment. Specifically, oxidative addition of a Pd(0)-catalyst into the N-O bond of O-pentafluorobenzoyl oxime esters generates imino-Pd(II) intermediates, which undergo 5-exo cyclization with sterically diverse alkenes. The resultant alkyl-Pd(II) intermediates are intercepted by organometallic nucleophiles or alcohols, under carbonylative or noncarbonylative conditions, to provide 1,2-carboamination products. This approach provides, for the first time, a unified strategy for achieving alkene 1,2-amino-acylation, -carboxylation, -arylation, -vinylation, and -alkynylation. For carbonylative processes, orchestrated protodecarboxylation of the pentafluorobenzoate leaving group underpins reaction efficiency. This process is likely a key feature in related Narasaka-Heck cyclizations and accounts for the efficacy of O-pentafluorobenzoyl oxime esters in aza-Heck reactions of this type. (Chemical Equation Presented).
- Faulkner, Adele,Scott, James S.,Bower, John F.
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supporting information
p. 7224 - 7230
(2015/06/25)
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- Cross-metathesis/isomerization/allylboration sequence for a diastereoselective synthesis of anti-homoallylic alcohols from allylbenzene derivatives and aldehydes
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We describe a highly diastereoselective approach to anti-homoallylic alcohols from allylbenzene derivatives and aldehydes. The strategy is based on a cross-metathesis/isomerization/allylboration sequence catalyzed successively by ruthenium and iridium. This methodology provides another way to access this class of compounds, which leads to the preparation of hitherto-unknown homoallylic alcohols without the requirement to control the stereochemistry of the 1-alkenyl boronate intermediates. Our study towards an enantioselective version of this sequential reaction is also reported.
- Hemelaere, Rmy,Carreaux, Franois,Carboni, Bertrand
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supporting information
p. 14518 - 14523
(2015/01/09)
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- A second-generation ligand for the enantioselective rhodium-catalyzed addition of arylboronic acids to alkenylazaarenes
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A 2,4,6-trialkylanilide-containing chiral diene has been identified as a superior ligand for the enantioselective rhodium-catalyzed arylation of alkenylazaarenes with arylboronic acids.
- Roy, Iain D.,Burns, Alan R.,Pattison, Graham,Michel, Boris,Parker, Alexandra J.,Lam, Hon Wai
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supporting information
p. 2865 - 2868
(2014/03/21)
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- Enantiomerically enriched tris(boronates): Readily accessible conjunctive reagents for asymmetric synthesis
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The catalytic enantioselective diboration of vinyl boronate esters furnishes chiral tris(boronates) in a selective fashion. Subsequent deborylative alkylation occurs in a diastereoselective fashion, both for intermolecular and intramolecular processes.
- Coombs, John R.,Zhang, Liang,Morken, James P.
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supporting information
p. 16140 - 16143
(2015/01/09)
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- Synthesis of Z-(pinacolato)allylboron and Z-(pinacolato)alkenylboron compounds through stereoselective catalytic cross-metathesis
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The first examples of catalytic cross-metathesis (CM) reactions that furnish Z-(pinacolato)allylboron and Z-(pinacolato)alkenylboron compounds are disclosed. Products are generated with high Z selectivity by the use of a W-based monoaryloxide pyrrolide (MAP) complex (up to 91% yield and >98:2 Z:E). The more sterically demanding Z-alkenylboron species are obtained in the presence of Mo-based MAP complexes in up to 93% yield and 97% Z selectivity. Z-selective CM with 1,3-dienes and aryl olefins are reported for the first time. The utility of the approach, in combination with catalytic cross coupling, is demonstrated by a concise and stereoselective synthesis of anticancer agent combretastatin A-4.
- Kiesewetter, Elizabeth T.,O'Brien, Robert V.,Yu, Elsie C.,Meek, Simon J.,Schrock, Richard R.,Hoveyda, Amir H.
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supporting information
p. 6026 - 6029
(2013/06/05)
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- Synthesis of alkenyl boronates from allyl-substituted aromatics using an olefin cross-metathesis protocol
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An efficient synthesis of 3-aryl-1-propenyl boronates from pinacol vinyl boronic ester and allyl-substituted aromatics by cross metathesis is reported. Although the allylbenzene derivatives are prone to isomerization reaction under metathesis conditions,
- Hemelaere, Remy,Carreaux, Francois,Carboni, Bertrand
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p. 6786 - 6792
(2013/07/26)
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- Enantioselective synthesis of anti homoallylic alcohols from terminal alkynes and aldehydes based on concomitant use of a cationic iridium complex and a chiral phosphoric acid
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We report a highly diastereo- and enantioselective synthesis of anti homoallylic alcohols from terminal alkynes via (E)-1-alkenylboronates based upon two catalytic reactions: a cationic iridium complex-catalyzed olefin transposition of (E)-1-alkenylboronates and a chiral phosphoric acid-catalyzed allylation reaction of aldehydes.
- Miura, Tomoya,Nishida, Yui,Morimoto, Masao,Murakami, Masahiro
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supporting information
p. 11497 - 11500
(2013/09/02)
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- Rhodium-catalyzed reaction of 1-alkenylboronates with aldehydes leading to allylation products
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Synthetic equivalents: 1-Alkenylboronates perform the role of an allylating reagent. Their reaction with aldehydes in the presence of a cationic rhodium(I)/dppm catalyst results in a highly diastereoselective production of anti-configured homoallylic alco
- Shimizu, Hiroshi,Igarashi, Tomohiro,Miura, Tomoya,Murakami, Masahiro
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supporting information; experimental part
p. 11465 - 11469
(2012/01/11)
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- Mild and general zinc-alkoxide-catalyzed allylations of ketones with allyl pinacol boronates
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A general and efficient zinc-alkoxide-catalyzed allylation of a diverse array of ketones with allyl boronates is presented. The methodology is effective with 2 mol % of catalyst and with relatively short reaction times. Studies of the key exchange process are presented, which support a cyclic transition state for the boron to zinc exchange.
- Fandrick, Keith R.,Fandrick, Daniel R.,Gao, Joe J.,Reeves, Jonathan T.,Tan, Zhulin,Li, Wenjie,Song, Jinhua J.,Lu, Bruce,Yee, Nathan K.,Senanayake, Chris H.
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supporting information; experimental part
p. 3748 - 3751
(2010/11/18)
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