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Search for "CH-activation" in Full Text gives 10 result(s) in Beilstein Journal of Organic Chemistry.
Asymmetric organocatalytic synthesis of chiral homoallylic amines
Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201
- deracemisation of an unsaturated amine 144 was reported by Li Dang and Xin-Yuan Liu (Scheme 30) [45]. They used CF3-radical-induced remote CH-activation, combined with Brønsted acid-catalysed chiral hydrogen atom transfer (HAT). In this reaction, triphenylphosphine first mediated the addition of the CF3-radical
High performance p-type molecular electron donors for OPV applications via alkylthiophene catenation chromophore extension
Beilstein J. Org. Chem. 2016, 12, 2298–2314, doi:10.3762/bjoc.12.223
- products significantly reduced the yield. For the quater- and quinquethiophenes N-iodosuccinimide (NIS) was used to give a clean product. Ideally, the synthesis could be further simplified by direct palladium-catalyzed CH-activation, arylation of 2 followed by reaction with the commercially available 5
- large scale use of tin reagents we required the key bis-borylated benzodithiophene (BDT) core 13, which was synthesised from the known BDT core 12 using iridium catalyzed borylation via CH-activation. The bis-borylated product was isolated by precipitation on addition of isopropanol (IPA), and an
Methylpalladium complexes with pyrimidine-functionalized N-heterocyclic carbene ligands
Beilstein J. Org. Chem. 2016, 12, 1557–1565, doi:10.3762/bjoc.12.150
- CDCl3, where two different signals for the m-pyrimidine protons are observed. We recently reported that the dihalogenato complexes are active catalysts of the methane CH activation in trifluoroacetic acid [34]. Under the reaction conditions it seems likely, that an exchange of the chloro against a
- ). We could also confirm the formation of the desired product by a solid state structure (Figure 4). Typical reaction conditions of the catalytic CH activation are 30 atmospheres of methane under strongly oxidizing conditions (potassium peroxodisulfate, trifluoroacetic acid and its anhydride), where
Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso–ene mechanism
Beilstein J. Org. Chem. 2015, 11, 2549–2556, doi:10.3762/bjoc.11.275
- -nitroso intermediate. Asymmetric induction is not observed using the chiral tetramine ligand (+)-(2R,2′R)-1,1′-bis(2-pyridylmethyl)-2,2′-bipyrrolidine ((R,R′)-PDP). Keywords: CH activation; hydroxyamination; iron catalysis; nitroso-ene; Introduction The selective functionalization of C–H bonds is an
Homogeneous and heterogeneous photoredox-catalyzed hydroxymethylation of ketones and keto esters: catalyst screening, chemoselectivity and dilution effects
Beilstein J. Org. Chem. 2014, 10, 1143–1150, doi:10.3762/bjoc.10.114
- reactions, the direct hydroxyalkylation of carbonyl compounds and carbonyl analogs is a demanding task because the α-CH activation of alcohols must occur in the presence of the acidic and nucleophilic hydroxy group. Thus, protection and deactivation of this group is necessary for thermal processes. In
Elucidation of the regio- and chemoselectivity of enzymatic allylic oxidations with Pleurotus sapidus – conversion of selected spirocyclic terpenoids and computational analysis
Beilstein J. Org. Chem. 2013, 9, 2233–2241, doi:10.3762/bjoc.9.262
- developed. The oxidations follow a radical mechanism and the regioselectivity of the reaction is mainly determined by bond-dissociation energies of the available allylic CH-bonds and steric accessibility of the oxidation site. Keywords: allylic oxidation; CH-activation; chiral separation; enones; flavors
Flexible synthesis of anthracycline aglycone mimics via domino carbopalladation reactions
Beilstein J. Org. Chem. 2013, 9, 2194–2201, doi:10.3762/bjoc.9.258
- -electrocyclization [39] or a direct CH-activation to the respective anthracycline precursor 13. The design of the dialkyne provides a simultaneous formation of the linear ring system. All four cycles were annulated in a single step, in which the B and C-ring were formed as a consequence of the reaction cascade
Cyclization of ortho-hydroxycinnamates to coumarins under mild conditions: A nucleophilic organocatalysis approach
Beilstein J. Org. Chem. 2012, 8, 1630–1636, doi:10.3762/bjoc.8.186
- agents [5][6]. Classical synthetic approaches for coumarins are based on the Perkin reaction or von Pechmann condensation, i.e., reactions under harsh conditions and at elevated temperatures [1]. Recent new methodologies based on CH-activation reactions still use acidic reaction media and show, in part
Tertiary alcohol preferred: Hydroxylation of trans-3-methyl-L-proline with proline hydroxylases
Beilstein J. Org. Chem. 2011, 7, 1643–1647, doi:10.3762/bjoc.7.193
- ability of non-heme iron(II) enzymes to oxidize tertiary carbon centers. To our knowledge, the formation of tertiary alcohols with α-ketoglutarate (α-KG) dependent iron(II) oxygenases has not been previously reported. These enzymes typically catalyze CH-activation reactions in primary and secondary
Synthesis of dihydrophenanthridines by a sequence of Ugi-4CR and palladium- catalyzed intramolecular C-H functionalization
Beilstein J. Org. Chem. 2008, 4, No. 10, doi:10.3762/bjoc.4.10
- -H, rather than the C2-H, of the pyridine. The more pronounced acidity of the C4-H could account for the observed regioselectivity [38]. The σ-H bond metathesis has been proposed as one of the major pathways to explain the palladium-catalyzed CH activation process. According to this mechanism, the CH
- -activation process would depend on the acidity of the CH to be activated rather than the electron density of the aromatic ring and those protons with higher acidity should be energetically more prone to be functionalized. This trend is indeed observed in the present study. The presence of a nitro group in
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