- Cobalt-Catalyzed C(sp2)-C(sp3) Suzuki-Miyaura Cross Coupling
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A cobalt-catalyzed method for the C(sp2)-C(sp3) Suzuki-Miyaura cross coupling of aryl boronic esters and alkyl bromides is described. Cobalt-ligand combinations were assayed with high-throughput experimentation, and cobalt(II) sources with trans-N,N′-dimethylcyclohexane-1,2-diamine (DMCyDA, L1) produced optimal yield and selectivity. The scope of this transformation encompassed steric and electronic diversity on the aryl boronate nucleophile as well as various levels of branching and synthetically valuable functionality on the electrophile. Radical trap experiments support the formation of electrophile-derived radicals during catalysis.
- Ludwig, Jacob R.,Simmons, Eric M.,Wisniewski, Steven R.,Chirik, Paul J.
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supporting information
(2020/11/02)
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- Air-Stable Iron-Based Precatalysts for Suzuki-Miyaura Cross-Coupling Reactions between Alkyl Halides and Aryl Boronic Esters
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The development of an air-stable iron(III)-based precatalyst for the Suzuki-Miyaura cross-coupling reaction of alkyl halides and unactivated aryl boronic esters is reported. Despite benefits to cost and toxicity, the proclivity of iron(II)-based complexes to undergo deactivationviaoxidation or hydrolysis is a limiting factor for their widespread use in cross-coupling reactions compared to palladium-based or nickel-based complexes. The new octahedral iron(III) complex demonstrates long-term stability on the benchtop as assessed by a combination of1H NMR spectroscopy, M?ssbauer spectroscopy, and its sustained catalytic activity after exposure to air. The improved stability of the iron-based catalyst facilitates an improved protocol in which Suzuki-Miyaura cross-coupling reactions of valuable substrates can be assembled without the use of a glovebox and access a diverse scope of products similar to reactions assembled in the glovebox with iron(II)-based catalysts.
- Wong, Alexander S.,Zhang, Bufan,Li, Bo,Neidig, Michael L.,Byers, Jeffery A.
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p. 2461 - 2472
(2021/11/01)
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- Rational Design of an Iron-Based Catalyst for Suzuki–Miyaura Cross-Couplings Involving Heteroaromatic Boronic Esters and Tertiary Alkyl Electrophiles
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Suzuki–Miyaura cross-coupling reactions between a variety of alkyl halides and unactivated aryl boronic esters using a rationally designed iron-based catalyst supported by β-diketiminate ligands are described. High catalyst activity resulted in a broad substrate scope that included tertiary alkyl halides and heteroaromatic boronic esters. Mechanistic experiments revealed that the iron-based catalyst benefited from the propensity for β-diketiminate ligands to support low-coordinate and highly reducing iron amide intermediates, which are very efficient for effecting the transmetalation step required for the Suzuki–Miyaura cross-coupling reaction.
- Byers, Jeffery A.,Crockett, Michael P.,Li, Bo,Wong, Alexander S.
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supporting information
p. 5392 - 5397
(2020/03/04)
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- Desulfonylative Arylation of Redox-Active Alkyl Sulfones with Aryl Bromides
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We describe the development of the first reductive cross-electrophile coupling between alkyl sulfones and aryl bromides. The use of alkyl sulfones offers strategic advantages over other alkyl electrophiles as they can be incorporated into molecules in unique ways and permit α-functionalization prior to coupling. The conditions developed here enable incorporation of a wide array of aromatic rings onto (fluoro)alkyl scaffolds with broad functional group tolerance and generality, making this a practical method for late-stage diversification.
- Hughes, Jonathan M. E.,Fier, Patrick S.
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supporting information
p. 5650 - 5654
(2019/08/01)
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- Decarboxylative Negishi Coupling of Redox-Active Aliphatic Esters by Cobalt Catalysis
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A cobalt-catalyzed decarboxylative Negishi coupling reaction of redox-active aliphatic esters with organozinc reagents was developed. The method enabled efficient alkyl–aryl, alkyl–alkenyl, and alkyl–alkynyl coupling reactions under mild reaction conditions with no external ligand or additive needed. The success of an in situ activation protocol and the facile synthesis of the drug molecule (±)-preclamol highlight the synthetic potential of this method. Mechanistic studies indicated that a radical mechanism is involved.
- Liu, Xu-Ge,Zhou, Chu-Jun,Lin,Han, Xiang-Lei,Zhang, Shang-Shi,Li, Qingjiang,Wang, Honggen
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p. 13096 - 13100
(2018/09/21)
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- Iron-Catalyzed Suzuki-Miyaura Cross-Coupling Reactions between Alkyl Halides and Unactivated Arylboronic Esters
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An iron-catalyzed cross-coupling reaction between alkyl halides and arylboronic esters was developed that does not involve activation of the boronic ester with alkyllithium reagents nor requires magnesium additives. A combination of experimental and theoretical investigations revealed that lithium amide bases coupled with iron complexes containing deprotonated cyanobis(oxazoline) ligands were best to obtain high yields (up to 89%) in catalytic cross-coupling reactions. Mechanistic investigations implicate carbon-centered radical intermediates and highlight the critical importance of avoiding conditions that lead to iron aggregates. The new iron-catalyzed Suzuki-Miyaura reaction was applied toward the shortest reported synthesis of the pharmaceutical Cinacalcet.
- Crockett, Michael P.,Tyrol, Chet C.,Wong, Alexander S.,Li, Bo,Byers, Jeffery A.
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supporting information
p. 5233 - 5237
(2018/09/12)
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- Decarboxylative Cross-Electrophile Coupling of N-Hydroxyphthalimide Esters with Aryl Iodides
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A new method for the decarboxylative coupling of alkyl N-hydroxyphthalimide esters (NHP esters) with aryl iodides is presented. In contrast to previous studies that form alkyl radicals from carboxylic acid derivatives, no photocatalyst, light, or arylmetal reagent is needed, only nickel and a reducing agent (Zn). Methyl, primary, and secondary alkyl groups can all be coupled in good yield (77% ave yield). One coupling with an acid chloride is also presented. Stoichiometric reactions of (dtbbpy)Ni(2-tolyl)I with an NHP ester show for the first time that arylnickel(II) complexes can directly react with NHP esters to form alkylated arenes.
- Huihui, Kierra M. M.,Caputo, Jill A.,Melchor, Zulema,Olivares, Astrid M.,Spiewak, Amanda M.,Johnson, Keywan A.,Dibenedetto, Tarah A.,Kim, Seoyoung,Ackerman, Laura K. G.,Weix, Daniel J.
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p. 5016 - 5019
(2016/05/19)
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- Nickel-catalyzed reductive coupling of aryl halides with secondary alkyl bromides and allylic acetate
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A room-temperature Ni-catalyzed reductive method for the coupling of aryl bromides with secondary alkyl bromides has been developed, providing C(sp 2)-C(sp3) products in good to excellent yields. Slight modification of this protocol allows efficient coupling of activated aryl chlorides with cyclohexyl bromide and aryl bromides with allylic acetate.
- Wang, Shulin,Qian, Qun,Gong, Hegui
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supporting information; experimental part
p. 3352 - 3355
(2012/08/08)
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- CAN-mediated oxidative cleavage of 4-aryl-3,4-dihydroxypiperidines
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A CAN-mediated oxidative cleavage of 4-aryl-3,4-dihydroxypiperidines 2Aa-Be to β-amino carbonyl compounds 3Aa-Be and 4Aa-Be in different ratios is described. This facile strategy was also used to synthesize racemic fluoxetine (5).
- Chang, Meng-Yang,Lin, Chun-Yu,Pai, Chun-Li
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p. 2565 - 2568
(2007/10/03)
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- Applications of the amino-cope rearrangement: Synthesis of tetrahydropyran, δ-lactone and piperidine targets
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We report a novel approach to some chiral tetrahydropyran and δ-lactone targets that utilizes the asymmetric amino-Cope rearrangement as a key synthetic step. Products of amino-Cope rearrangement chemistry have also been applied to access piperidine targe
- Allin, Steven M.,Essat, Munira,Pita, Catalina Horro,Baird, Robert D.,McKee, Vickie,Elsegood, Mark,Edgar, Mark,Andrews, David M.,Shah, Pritom,Aspinall, Ian
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p. 809 - 815
(2007/10/03)
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- Nickel-catalyzed cross-couplings of organosilicon reagents with unactivated secondary alkyl bromides
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A metal-catalyzed cross-coupling of organosilicon compounds with alkyl halides has been developed. Noteworthy attributes of the method are its scope (secondary electrophiles), its high functional-group compatibility, and the air stability of the catalyst components. Copyright
- Powell, David A.,Fu, Gregory C.
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p. 7788 - 7789
(2007/10/03)
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