- Titanocenes as Photoredox Catalysts Using Green-Light Irradiation
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Irradiation of Cp2TiCl2 with green light leads to electronically excited [Cp2TiCl2]*. This complex constitutes an efficient photoredox catalyst for the reduction of epoxides and for 5-exo cyclizations of suitably unsaturated epoxides. To the best of our knowledge, our system is the first example of a molecular titanium photoredox catalyst.
- Flowers, Robert A.,Gans?uer, Andreas,Hilche, Tobias,Oloyede, Ugochinyere N.,Rietdijk, Niels R.,Slak, Daniel,Zhang, Zhenhua
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supporting information
p. 9355 - 9359
(2020/04/30)
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- Ligand-Controlled Direct Hydroformylation of Trisubstituted Olefins
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The direct hydroformylation of trisubstituted olefins has been achieved with a combination of a Rh(I) catalyst and a π-acceptor phosphorus (briphos) ligand. A sterically bulky briphos ligand with a large cone angle that forms a 1:1 complex with Rh(I) is found to be reactive for the hydroformylation of trisubstituted olefins. The aldehyde products were obtained with high diastereoselectivity (>99:1) and regioselectivity (49%-81%).
- Shin, Taeil,Kim, Hyungsoo,Kim, Sungmin,Lee, Ansoo,Seo, Min-Seob,Choi, Jonghoon,Kim, Hyungjun,Kim, Hyunwoo
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p. 5789 - 5792
(2019/06/24)
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- Merging Catalysis in Single Electron Steps with Photoredox Catalysis - Efficient and Sustainable Radical Chemistry
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We describe a combination of catalysts that allows the coupling of titanocene(III) catalysis with photoredox catalysis. Oxidation of radical intermediates by a photoredox catalyst opens novel catalytic mechanisms for reductive epoxide ring opening and redox-neutral epoxide radical arylation. In the former case, the requirement of metallic reductants and stoichiometric acidic additives is bypassed.
- Zhang, Zhenhua,Richrath, Ruben B.,Gans?uer, Andreas
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p. 3208 - 3212
(2019/04/13)
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- Cu-Catalyzed Hydroxymethylation of Unactivated Alkyl Iodides with CO To Provide One-Carbon-Extended Alcohols
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We have developed a reductive carbonylation method by which unactivated alkyl iodides can be hydroxymethylated to provide one-carbon-extended alcohol products under Cu-catalyzed conditions. The method is tolerant of alkyl β-hydrogen atoms, is robust towards a wide variety of functional groups, and was applied to primary, secondary, and tertiary alkyl iodide substrates. Mechanistic experiments indicate that the transformation proceeds by atom-transfer carbonylation (ATC) of the alkyl iodide followed in tandem by two CuH-mediated reductions in rapid succession. This radical mechanism renders the Cu-catalyzed system complementary to precious-metal-catalyzed reductive carbonylation reactions.
- Zhao, Siling,Mankad, Neal P.
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supporting information
p. 5867 - 5870
(2018/04/17)
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- Determination of the Absolute Configuration of β-Chiral Primary Alcohols Using the Competing Enantioselective Conversion Method
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A method for determining the absolute configuration of β-chiral primary alcohols has been developed. Enantioenriched alcohols were acylated in the presence of either enantiomer of the enantioselective acylation catalyst HBTM, and the faster reaction was determined by measuring product conversion using 1H NMR spectroscopic analysis. An empirical mnemonic was developed that correlates the absolute configuration of the alcohol to the faster reacting catalyst. Successful substrates for this method include primary alcohols that bear a "directing group" on the stereogenic center; directing groups include arenes, heteroarenes, enones, and halides.
- Burns, Alexander S.,Wagner, Alexander J.,Fulton, Jennifer L.,Young, Kyle,Zakarian, Armen,Rychnovsky, Scott. D.
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supporting information
p. 2953 - 2956
(2017/06/07)
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- BIARYL PYRAZOLES AS NRF2 REGULATORS
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The present invention relates to biaryl pyrazole compounds, methods of making them, pharmaceutical compositions containing them and their use as NRF2 regulators.
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Page/Page column 451; 452
(2017/08/01)
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- Highly Active Titanocene Catalysts for Epoxide Hydrosilylation: Synthesis, Theory, Kinetics, EPR Spectroscopy
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A catalytic system for titanocene-catalyzed epoxide hydrosilylation is described. It features a straightforward preparation of titanocene hydrides that leads to a reaction with low catalyst loading, high yields, and high selectivity of radical reduction. The mechanism was studied by a suite of methods, including kinetic studies, EPR spectroscopy, and computational methods. An unusual resting state leads to the observation of an inverse rate order with respect to the epoxide.
- Henriques, Dina Schwarz G.,Zimmer, Katharina,Klare, Sven,Meyer, Andreas,Rojo-Wiechel, Elena,Bauer, Mirko,Sure, Rebecca,Grimme, Stefan,Schiemann, Olav,Flowers, Robert A.,Gans?uer, Andreas
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supporting information
p. 7671 - 7675
(2016/07/07)
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- NRF2 REGULATORS
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Provided are aryl analogs,pharmaceutical compositions containing them and their use as NRF2 regulators.
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Page/Page column 346; 347
(2017/01/02)
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- Chiral monodentate phosphine ligands for the enantioselective α- And γ-arylation of aldehydes
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The synthesis of chiral variants of monodentate trialkyl and dialkylbiaryl phosphine ligands elaborated on the binepine scaffold is described. Their application in the Pd-catalyzed intramolecular asymmetric α-arylation of aldehydes and the intermolecular asymmetric γ-arylation of α,β-unsaturated aldehydes provides a mean of validating the design of these ligands. For the first reaction, excellent reactivities have been obtained while only modest enantioselectivities were measured. Aside from enantioselectivity, the second reaction offers additional challenges associated with intramolecularity and regioselectivity. With the formal chiral trialkyl monodentate phosphine ligands, good yield, high olefin stereocontrol, and perfect γ-selectivity were obtained while the enantioselectivity remained in the low but promising range.
- Franzoni, Ivan,Guénée, Laure,Mazet, Clément
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supporting information
p. 4181 - 4190
(2014/06/09)
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- Formic acid: A promising bio-renewable feedstock for fine chemicals
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In light of the growing scarcity of petroleum-based raw materials, carbon dioxide (CO2) is becoming increasing attractive as organic carbon source. In this perspective, formic acid (HCOOH) might be an interesting bio-renewable solution to store, transport, and activate carbon dioxide for the synthesis of value-added chemicals. Herein, HCOOH has been successfully used as C1 building block for the synthesis of a library of alcohols via a catalysed oxo-synthesis, under green experimental conditions. Copyright
- Mura, Manuel G.,Luca, Lidia De,Giacomelli, Giampaolo,Porcheddu, Andrea
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supporting information
p. 3180 - 3186
(2013/01/15)
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- Compounds having protected hydroxy groups
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The present invention relates to compounds with protected hydroxy groups of formula (I) These compounds are precursors for organoleptic agents, such as fragrances, and masking agents and for antimicrobial agents. When activated, the compounds of formula (I) are cleaved and form one or more organoleptic and/or antimicrobial compounds.
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- Water/MAO acceleration of the zirconocene-catalyzed asymmetric methylalumination of α-olefins
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(matrix presented) The zirconocene-catalyzed enantioselective methylalumination of terminal alkenes is greatly accelerated in the presence of water. Terminal olefins that are inert under the standard conditions can be readily methylated in good yields and with good to high enantioselectivities. Furthermore, methylaluminoxane is also shown to accelerate the reaction, albeit at a lesser rate.
- Wipf, Peter,Ribe, Seth
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p. 1713 - 1716
(2007/10/03)
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- Non-chelation controlled 1,3-asymmetric induction in β-chiral acylsilanes
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The diastereoselectivity of nucleophilic adition to β-chiral acylsilanes is examined, and our method is applied to the stereoselective synthesis of calcitriol lactone, a major metabolite of vitamin D3.
- Nakada, Masahisa,Urano, Yasuharu,Kobayashi, Susumu,Ohno, Masaji
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p. 741 - 744
(2007/10/02)
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- Reductive Carbonylation of Alkenes using Zwitterionic Rhodium Complexes as Catalysts
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Alkenes react with carbon monoxide, sodium borohydride, propan-2-ol and a catalytic amount of Rh(cod)(η6-PhBPh3) (cod = cyclooctadiene) to give alcohols in fine yields; high regioselectivity for the branched or linear alcohol is usually observed, depending on the organic substrate.
- Zhou, Jian-Qiang,Alper, Howard
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p. 233 - 234
(2007/10/02)
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- Enhanced Cram Selectivity in Carbonyl Alkylation via 'Naked ' Anions and anti-Cram Selectivity via 'Naked' Cuprates
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Enhanced Cram selectivity is observed via the reaction of aldehydes (1) with 'naked' anions (2) prepared in situ from RM and Bu4NBr, while anti-Cram selectivity results from the reaction of (1) with 'naked' cuprates (4) prepared in situ from R2CuLi and Bu4NBr.
- Yamamoto, Yoshinori,Matsuoka, Koshin
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p. 923 - 924
(2007/10/02)
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- REGIOSELECTIVITY OF THE REACTIONS OF TRIALKYLALUMINUM REAGENTS WITH 2,3-EPOXYALCOHOLS: APPLICATION TO THE SYNTHESIS OF α-CHIRAL ALDEHYDES
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Treatment of optically active 2,3-epoxyalcohols with trialkylaluminum reagents followed by periodate cleavage constitutes a convenient synthesis of α-chiral aldehyde derivatives, especially when the branching alkyl group is methyl.
- Roush, William R.,Adam, Michael A.,Peseckis, Steven M.
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p. 1377 - 1380
(2007/10/02)
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