- Enantioselective Conjugate Addition of Stabilized Arylzinc Iodide to Enones: an Improved Protocol of the Hayashi Reaction
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Stabilised arylzinc iodide, prepared by direct insertion of zinc into aryl iodides, were used as nucleophiles in the Hayashi Rh-catalysed enantioselective conjugate addition to enones. The reaction conditions were optimized in the addition of phenylzinc i
- Casotti, Gianluca,Rositano, Vincenzo,Iuliano, Anna
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p. 1126 - 1131
(2020/12/17)
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- Rhodium-Catalyzed Addition of Organozinc Iodides to Carbon-11 Isocyanates
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Amides were prepared using rhodium-catalyzed coupling of organozinc iodides and carbon-11 (11C, t1/2 = 20.4 min) isocyanates. Nonradioactive isocyanates and sp3 or sp2 organozinc iodides generated amides in yields of 13%-87%. Incorporation of cyclotron-produced [11C]CO2 into 11C-amide products proceeded in yields of 5%-99%. The synthetic utility of the methodology was demonstrated through the isolation of [11C]N-(4-fluorophenyl)-4-methoxybenzamide ([11C]6g) with a molar activity of 267 GBq μmol-1 and 12% radiochemical yield in 21 min from the beginning of synthesis.
- Fouad, Moustafa H.,Ismailani, Uzair S.,Mair, Braeden A.,Munch, Maxime,Rotstein, Benjamin H.
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supporting information
p. 2746 - 2750
(2020/04/16)
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- Nickel-Catalyzed α-Carbonylalkylarylation of Vinylarenes: Expedient Access to γ,γ-Diarylcarbonyl and Aryltetralone Derivatives
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We report a Ni-catalyzed regioselective α-carbonylalkylarylation of vinylarenes with α-halocarbonyl compounds and arylzinc reagents. The reaction works with primary, secondary, and tertiary α-halocarbonyl molecules, and electronically varied arylzinc reagents. The reaction generates γ,γ-diarylcarbonyl derivatives with α-secondary, tertiary, and quaternary carbon centers. The products can be readily converted to aryltetralones, including a precursor to Zoloft, an antidepressant drug.
- Dhungana, Roshan K.,Giri, Ramesh,Khanal, Namrata,Shekhar, K. C.
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supporting information
p. 8047 - 8051
(2020/04/30)
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- Arylzinc Halides by Silver Catalyzed Zinc Insertion into Aryl Iodides
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A catalytic amount of silver acetate efficiently promotes direct insertion of zinc metal into aryl iodides, having different structure, in ethereal solvent. Electron-rich substrates also rapidly undergo oxidative metalation. The arylzinc iodides formed give Negishi coupling products under mild reaction conditions to obtain biaryls in high yields. Sensitive functional groups like aldehydes and primary amides are well-tolerated.
- Casotti, Gianluca,Iuliano, Anna,Carpita, Adriano
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p. 1021 - 1026
(2019/01/04)
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- Ni-Catalyzed Regioselective β,δ-Diarylation of Unactivated Olefins in Ketimines via Ligand-Enabled Contraction of Transient Nickellacycles: Rapid Access to Remotely Diarylated Ketones
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We disclose a [(PhO)3P]/NiBr2-catalyzed regioselective β, δ-diarylation of unactivated olefins in ketimines with aryl halides and arylzinc reagents. This diarylation proceeds at remote locations to the carbonyl group to afford, after simple H+ workup, diversely substituted β, δ-diarylketones that are otherwise difficult to access readily with existing methods. Deuterium-labeling and crossover experiments indicate that diarylation proceeds by ligand-enabled contraction of transient nickellacycles.
- Basnet, Prakash,Dhungana, Roshan K.,Thapa, Surendra,Shrestha, Bijay,Kc, Shekhar,Sears, Jeremiah M.,Giri, Ramesh
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p. 7782 - 7786
(2018/06/22)
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- Mechanochemical Activation of Zinc and Application to Negishi Cross-Coupling
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A form independent activation of zinc, concomitant generation of organozinc species and engagement in a Negishi cross-coupling reaction via mechanochemical methods is reported. The reported method exhibits a broad substrate scope for both C(sp3)–C(sp2) and C(sp2)–C(sp2) couplings and is tolerant to many important functional groups. The method may offer broad reaching opportunities for the in situ generation organometallic compounds from base metals and their concomitant engagement in synthetic reactions via mechanochemical methods.
- Cao, Qun,Howard, Joseph L.,Wheatley, Emilie,Browne, Duncan L.
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supporting information
p. 11339 - 11343
(2018/08/28)
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- Ni-Catalyzed Regioselective Alkylarylation of Vinylarenes via C(sp3)-C(sp3)/C(sp3)-C(sp2) Bond Formation and Mechanistic Studies
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We report a Ni-catalyzed regioselective alkylarylation of vinylarenes with alkyl halides and arylzinc reagents to generate 1,1-diarylalkanes. The reaction proceeds well with primary, secondary and tertiary alkyl halides, and electronically diverse arylzinc reagents. Mechanistic investigations by radical probes, competition studies and quantitative kinetics reveal that the current reaction proceeds via a Ni(0)/Ni(I)/Ni(II) catalytic cycle by a rate-limiting direct halogen atom abstraction via single electron transfer to alkyl halides by a Ni(0)-catalyst.
- Kc, Shekhar,Dhungana, Roshan K.,Shrestha, Bijay,Thapa, Surendra,Khanal, Namrata,Basnet, Prakash,Lebrun, Robert W.,Giri, Ramesh
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supporting information
p. 9801 - 9805
(2018/08/06)
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- Ni-Catalyzed Regioselective Dicarbofunctionalization of Unactivated Olefins by Tandem Cyclization/Cross-Coupling and Application to the Concise Synthesis of Lignan Natural Products
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We disclose a (terpy)NiBr2-catalyzed reaction protocol that regioselectively difunctionalizes unactivated olefins with tethered alkyl halides and arylzinc reagents. The reaction shows an excellent functional group tolerance (such as ketones, es
- Kc, Shekhar,Basnet, Prakash,Thapa, Surendra,Shrestha, Bijay,Giri, Ramesh
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p. 2920 - 2936
(2018/03/09)
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- Synergistic Bimetallic Ni/Ag and Ni/Cu Catalysis for Regioselective γ,δ-Diarylation of Alkenyl Ketimines: Addressing β-H Elimination by in Situ Generation of Cationic Ni(II) Catalysts
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We disclose unprecedented synergistic bimetallic Ni/Ag and Ni/Cu catalysts for regioselective γ,δ-diarylation of unactivated alkenes in simple ketimines with aryl halides and arylzinc reagents. The bimetallic synergy, which generates cationic Ni(II) speci
- Basnet, Prakash,Kc, Shekhar,Dhungana, Roshan K.,Shrestha, Bijay,Boyle, Timothy J.,Giri, Ramesh
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supporting information
p. 15586 - 15590
(2018/11/23)
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- Single-electron-transfer-induced coupling of arylzinc reagents with aryl and alkenyl halides
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Arylzinc reagents, prepared from aryl halides/zinc powder or aryl Grignard reagents/zinc chloride, were found to undergo coupling with aryl and alkenyl halides without the aid of transition-metal catalysis to give biaryls and styrene derivatives, respectively. In this context, we have already reported the corresponding reaction using aryl Grignard reagents instead of arylzinc reagents. Compared with the Grignard cross-coupling, the present reaction features high functional-group tolerance, whereby electrophilic groups such as alkoxycarbonyl and cyano groups are compatible as substituents on both the arylzinc reagents and the aryl halides. Aryl halides receive a single electron and thereby become activated as the corresponding anion radicals, which react with arylzinc reagents, thus leading to the cross-coupling products. Arylzinc reagents were found to undergo coupling with aryl and alkenyl halides to give biaryl and styrene derivatives, respectively. The cross-coupling, which features high functional-group tolerance, proceeds through a single-electron-transfer mechanism and thus does not require the aid of transition-metal catalysis.
- Shirakawa, Eiji,Tamakuni, Fumiko,Kusano, Eugene,Uchiyama, Nanase,Konagaya, Wataru,Watabe, Ryo,Hayashi, Tamio
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supporting information
p. 521 - 525
(2014/01/23)
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- Stereoconvergent arylations and alkenylations of unactivated alkyl electrophiles: Catalytic enantioselective synthesis of secondary sulfonamides and sulfones
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The development of efficient methods for the generation of enantioenriched sulfonamides and sulfones is an important objective for fields such as organic synthesis and medicinal chemistry; however, there have been relatively few reports of direct catalytic asymmetric approaches to controlling the stereochemistry of the sulfur-bearing carbon of such targets. In this report, we describe nickel-catalyzed stereoconvergent Negishi arylations and alkenylations of racemic α-bromosulfonamides and -sulfones that furnish the desired cross-coupling product in very good ee and yield for an array of reaction partners. Mechanistic studies are consistent with the generation of a radical intermediate that has a sufficient lifetime to diffuse out of the solvent cage and to cyclize onto a pendant olefin.
- Choi, Junwon,Martín-Gago, Pablo,Fu, Gregory C.
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supporting information
p. 12161 - 12165
(2014/11/07)
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- Efficient synthetic method for the preparation of allyl- and propargyl-epoxides by allylation and propargylation of α-haloketones with organozinc reagents
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A simple, efficient, and non-metal catalyzed synthetic method for the preparation of substituted allyl- and propargyl-epoxides by allylation and propargylation of α-halo ketones with organozinc reagents in mild conditions is reported in this paper. The present method complements the existing synthetic methods due to some advantageous properties of the organozinc reagents such as availability, selectivity, operational simplicity and low toxicity.
- Pan, Jie,Zhang, Min,Zhang, Songlin
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p. 1060 - 1067
(2012/04/10)
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- Efficient synthesis of functionalized organozinc compounds by the direct insertion of zinc into organic iodides and bromides
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(Chemical Equation Presented) Insider dealing: A wide range of poly-functional (hetero)aromatic and aliphatic zinc reagents can be easily prepared in THF. The compounds are formed by a Zn insertion reaction mediated by the addition of LiCl (see scheme; All = allyl).
- Krasovskiy, Arkady,Malakhov, Vladimir,Gavryushin, Andrei,Knochel, Paul
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p. 6040 - 6044
(2007/10/03)
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- Copper-Catalyzed Electrophilic Amination of Diorganozinc Reagents
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The copper-catalyzed electrophilic amination of diorganozinc reagents employing O-acyl N,N-dialkyl hydroxylamine derivatives as aminating agents is described. This reaction offers a general method for the preparation of tertiary amines in high yields and is noteworthy for its convenience both in terms of reaction conditions employed (room temperature, ≤1 h) and ease of product isolation (acid/base extractive workup). Copyright
- Berman, Ashley M.,Johnson, Jeffrey S.
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p. 5680 - 5681
(2007/10/03)
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- Ultrasound-Promoted Synthesis of Arylzinc Compounds Using Zinc Powder and Their Application to Palladium(0)-Catalyzed Synthesis of Multifunctional Biaryls
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Arylzinc compounds containing electron-withdrawing groups such as CO2CH3, CON(CH3)2, CN, Br, Cl, or CF3 at ortho position were prepared readily by the ultrasound-promoted reaction of aryl iodides with zinc powder, which were applied to palladium(0)-catalyzed cross-coupling with aryl halides to afford unsymmetrical and multifunctional biaryls in good yields.
- Takagi, Kentaro
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p. 469 - 472
(2007/10/02)
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