- Light- and Manganese-Initiated Borylation of Aryl Diazonium Salts: Mechanistic Insight on the Ultrafast Time-Scale Revealed by Time-Resolved Spectroscopic Analysis
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Manganese-mediated borylation of aryl/heteroaryl diazonium salts emerges as a general and versatile synthetic methodology for the synthesis of the corresponding boronate esters. The reaction proved an ideal testing ground for delineating the Mn species responsible for the photochemical reaction processes, that is, involving either Mn radical or Mn cationic species, which is dependent on the presence of a suitably strong oxidant. Our findings are important for a plethora of processes employing Mn-containing carbonyl species as initiators and/or catalysts, which have considerable potential in synthetic applications.
- Firth, James D.,Hammarback, L. Anders,Burden, Thomas J.,Eastwood, Jonathan B.,Donald, James R.,Horbaczewskyj, Chris S.,McRobie, Matthew T.,Tramaseur, Adam,Clark, Ian P.,Towrie, Michael,Robinson, Alan,Krieger, Jean-Philippe,Lynam, Jason M.,Fairlamb, Ian J. S.
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p. 3979 - 3985
(2021/02/03)
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- 11-Step and Scalable Total Synthesis of Hamigeran M Enabled by Five C-H Functionalizations
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We report the convergent total synthesis of (±)-hamigeran M, enabled by five C-H functionalization reactions and proceeding in 11 steps in 3.9% overall yield. The C-H functionalizations include a hydroxy-directed C-H borylation, one C-H metalation-1,2-addition, one C-H metalation-Negishi coupling, a late-stage oxazole-directed C-H borylation-oxidation, and one electrophilic bromination. Two of these five C-H functionalizations forged strategic C-C bonds in the seven-membered ring of hamigeran M. The oxazole-directed C-H borylation-oxidation was unprecedented and ensured a late-stage hydroxylation. Other key steps include a tandem Suzuki reaction-lactonization to join the cyclopentane building block with the aromatic moiety and a hydrogen-atom transfer reaction to reduce a challenging tetrasubstituted double bond.
- Jiang, Baiyang,Dai, Mingji
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supporting information
p. 20084 - 20089
(2021/12/03)
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- Understanding the Activation of Air-Stable Ir(COD)(Phen)Cl Precatalyst for C-H Borylation of Aromatics and Heteroaromatics
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A newly developed robust catalyst [Ir(COD)(Phen)Cl] (A) was used for the C-H borylation of three dozen aromatics and heteroaromatics with excellent yield and selectivity. Activation of the catalyst was identified by the use of catalytic amounts of water, alcohols, etc., when B2pin2 was used in noncoordinating solvents, while for THF catalytic use of HBpin was required. The results were on par with the in situ based expensive system [Ir(OMe)(COD)]2/dtbbpy or Me4Phen.
- Slack, Eric D.,Colacot, Thomas J.
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supporting information
p. 1561 - 1565
(2021/02/20)
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- Ruthenium-catalyzed regio- And site-selective: Ortho C-H borylation of phenol derivatives
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Efficient synthesis of o-borylphenols is achieved through the Ru-catalyzed regio- and site-selective sp2 C-H borylation of aryl diphenylphosphinites followed by removal of the phosphorus directing group. A successful application to aryl phosphites enables practical one-pot borylation of phenols, demonstrating high synthetic utility of this protocol.
- Homma, Yuki,Fukuda, Kazuishi,Iwasawa, Nobuharu,Takaya, Jun
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supporting information
p. 10710 - 10713
(2020/10/02)
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- Ir-Catalyzed ortho-Borylation of Phenols Directed by Substrate-Ligand Electrostatic Interactions: A Combined Experimental/in Silico Strategy for Optimizing Weak Interactions
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A strategy for affecting ortho versus meta/para selectivity in Ir-catalyzed C-H borylations (CHBs) of phenols is described. From selectivity observations with ArylOBpin (pin = pinacolate), it is hypothesized that an electrostatic interaction between the partial negatively charged OBpin group and the partial positively charged bipyridine ligand of the catalyst favors ortho selectivity. Experimental and computational studies designed to test this hypothesis support it. From further computational work a second generation, in silico designed catalyst emerged, where replacing Bpin with Beg (eg = ethylene glycolate) was predicted to significantly improve ortho selectivity. Experimentally, reactions employing B2eg2 gave ortho selectivities > 99%. Adding triethylamine significantly improved conversions. This ligand-substrate electrostatic interaction provides a unique control element for selective C-H functionalization.
- Chattopadhyay, Buddhadeb,Dannatt, Jonathan E.,Andujar-De Sanctis, Ivonne L.,Gore, Kristin A.,Maleczka, Robert E.,Singleton, Daniel A.,Smith, Milton R.
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supporting information
p. 7864 - 7871
(2017/06/20)
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- Regioselective Synthesis of o-Benzenediboronic Acids via Ir-Catalyzed o-C-H Borylation Directed by a Pyrazolylaniline-Modified Boronyl Group
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Ir-catalyzed ortho-directed C-H borylation of pyrazolylaniline (PZA)-modified arylboronic acids with bis(pinacolate)diboron afforded o-benzenediboronic acids in which two boronyl groups are differentially modified by pinacol (PIN) and PZA. By using this borylation after nondirected Ir-catalyzed C-H borylation, o-benzenediboronic acids are conveniently synthesized from unfunctionalized arenes. The differentially modified o-benzenediboronic acids undergo selective oxidation and Suzuki-Miyaura cross-coupling at the PZA-modified boronyl groups, affording o-functionalized arylboronic acids selectively.
- Yamamoto, Takeshi,Ishibashi, Aoi,Suginome, Michinori
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p. 886 - 889
(2017/02/26)
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- Preparation of Aryne-Nickel Complexes from ortho-Borylaryl Triflates
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A facile method for preparing diverse aryne-nickel complexes from readily synthesized ortho-borylaryl triflates is described. Exploratory synthetic applications, including the synthesis of 1,2-difunctionalized arenes, based on the nucleophilic character of the aryne-nickel complexes are also demonstrated.
- Sumida, Yuto,Sumida, Tomoe,Hashizume, Daisuke,Hosoya, Takamitsu
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supporting information
p. 5600 - 5603
(2016/11/17)
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- Use of 2-bromophenylboronic esters as benzyne precursors in the Pd-catalyzed synthesis of triphenylenes
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ortho-Substituted aryl boronates are introduced as aryne precursors for transition-metal-catalyzed transformations. On treatment with tBuOK and Pd(0), metal-bound aryne intermediates are formed that undergo effective trimerization to form useful triphenylene compounds. For meta-substituted arynes, the 3:1 product ratio in favor of non-C3 symmetric material is indicative of a benzyne mechanism.
- Garcia-Lopez, Jose-Antonio,Greaney, Michael F.
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p. 2338 - 2341
(2014/05/20)
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- Rh/Pd catalysis with chiral and achiral ligands: Domino synthesis of aza-dihydrodibenzoxepines
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A game of dominoes: A synthetic route to aza-dihydrodibenzoxepines is described, through the combination of a Rh-catalyzed arylation and a Pd-catalyzed C-O coupling in a single pot. For the first time, the ability to incorporate a chiral and an achiral ligand in a two-component, two-metal transformation is achieved, giving the products in moderate to good yields, with excellent enantioselectivities. Copyright
- Friedman, Adam A.,Panteleev, Jane,Tsoung, Jennifer,Huynh, Vaizanne,Lautens, Mark
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p. 9755 - 9758
(2013/09/23)
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- SOLUBLE GUANYLATE CYCLASE ACTIVATORS
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The present invention relates to compounds of formula (I): and pharmaceutically acceptable salts thereof, wherein R1, R2. R3, R4, R5, R6, A and B are as defined herein. The invention also r
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Page/Page column 64-65
(2012/09/22)
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