- Decarbonylative Fluoroalkylation at Palladium(II): From Fundamental Organometallic Studies to Catalysis
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This Article describes the development of a decarbonylative Pd-catalyzed aryl-fluoroalkyl bond-forming reaction that couples fluoroalkylcarboxylic acid-derived electrophiles [RFC(O)X] with aryl organometallics (Ar-M′). This reaction was optimized by interrogating the individual steps of the catalytic cycle (oxidative addition, carbonyl de-insertion, transmetalation, and reductive elimination) to identify a compatible pair of coupling partners and an appropriate Pd catalyst. These stoichiometric organometallic studies revealed several critical elements for reaction design. First, uncatalyzed background reactions between RFC(O)X and Ar-M′ can be avoided by using M′ = boronate ester. Second, carbonyl de-insertion and Ar-RF reductive elimination are the two slowest steps of the catalytic cycle when RF = CF3. Both steps are dramatically accelerated upon changing to RF = CHF2. Computational studies reveal that a favorable F2C-H - -X interaction contributes to accelerating carbonyl de-insertion in this system. Finally, transmetalation is slow with X = difluoroacetate but fast with X = F. Ultimately, these studies enabled the development of an (SPhos)Pd-catalyzed decarbonylative difluoromethylation of aryl neopentylglycol boronate esters with difluoroacetyl fluoride.
- Lalloo, Naish,Malapit, Christian A.,Taimoory, S. Maryamdokht,Brigham, Conor E.,Sanford, Melanie S.
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supporting information
p. 18617 - 18625
(2021/11/16)
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- Mechanism and Scope of Nickel-Catalyzed Decarbonylative Borylation of Carboxylic Acid Fluorides
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This Article describes the development of a base-free, nickel-catalyzed decarbonylative coupling of carboxylic acid fluorides with diboron reagents to selectively afford aryl boronate ester products. Detailed studies were conducted to assess the relative rates of direct transmetalation between aryl boronate esters and diboron reagents and a bisphosphine nickel(aryl)(fluoride) intermediate. These investigations revealed that diboron reagents undergo transmetalation with this Ni(aryl)(fluoride) intermediate at rates significantly faster than their aryl boronate ester congeners. Furthermore, the reactivity of both boron reagents toward transmetalation is enhanced with increasing electrophilicity of the boron center. These mechanistic insights were leveraged to develop a catalytic decarbonylative borylation of acid fluorides that proved applicable to a variety of (hetero)aryl carboxylic acid fluorides as well as diverse diboron reagents. The acid fluorides can be generated in situ directly from carboxylic acids. Furthermore, the mechanistic studies directed the identification of various air-stable Ni pre-catalysts for this transformation.
- Malapit, Christian A.,Bour, James R.,Laursen, Simon R.,Sanford, Melanie S.
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supporting information
p. 17322 - 17330
(2019/11/03)
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- Copper-catalyzed amination of arylboronates with N,N-dialkylhydroxylamines
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A tolerant coupling: The title reaction has been developed to deliver arylamines (see scheme; Bz=benzoyl, dppbz=1,2-bis(diphenylphosphino)benzene). The catalysis is based on electrophilic, umpolung amination and enables the use of secondary acyclic amines. Various functional groups are tolerated, thus opening up a new substrate class for the Chan-Lam-type coupling.
- Matsuda, Naoki,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
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supporting information; body text
p. 3642 - 3645
(2012/05/20)
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- Borylation of aryl and alkenyl carbamates through Ni-catalyzed C-O activation
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Direct borylation of aryl/alkenyl carbamates was developed through Ni catalysis. A broad substrate scope, including aryl, alkenyl, and heterocyclic derivatives, was studied. This study offers a convenient method to approach aryl/alkenyl boronic esters from phenol and ketone derivatives (see scheme). Copyright
- Huang, Kun,Yu, Da-Gang,Zheng, Shu-Fang,Wu, Zhen-Hua,Shi, Zhang-Jie
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experimental part
p. 786 - 791
(2011/03/20)
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- Carboxylation of organoboronic esters catalyzed by N-heterocyclic carbene copper(I) complexes
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Copper complexes with a CO2 fixation: Copper(I) complexes serve as excellent catalysts for the carboxylation of aryl- and alkenylboronic esters with CO2, affording a variety of functionalized carboxylic acid derivatives (see scheme). Important active intermediates such as the copper(I) aryl and carboxylate complexes, [(IPr)CuR] and [(IPr)CuOCOR] (R = 4-MeOC 6H4, IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2- ylidene), are isolated and structurally characterized. (Chemical Equation Presented).
- Ohishi, Takeshi,Nishiura, Masayoshi,Hou, Zhaomin
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supporting information; experimental part
p. 5792 - 5795
(2009/03/11)
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