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Search for "radical reactions" in Full Text gives 77 result(s) in Beilstein Journal of Organic Chemistry.
Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances
- Thiago S. Silva and
- Fernando Coelho
Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112
- tend to recombine and eventually generate benzylcobalamin in a parasite pathway. However, the presence of Ti(III) citrate reduces the Co(II) radical, thereby overcoming the “persistent radical effect” observed in cobalt-mediated radical reactions and allowing benzylic radical dimerization to afford 33
Graphical Abstract
Figure 1: Some examples of natural products and drugs containing quaternary carbon centers.
Scheme 1: Simplified mechanism for olefin hydrofunctionalization using an electrophilic transition metal as a...
Scheme 2: Selected examples of quaternary carbon centers formed by the intramolecular hydroalkylation of β-di...
Scheme 3: Control experiments and the proposed mechanism for the Pd(II)-catalyzed intermolecular hydroalkylat...
Scheme 4: Intermolecular olefin hydroalkylation of less reactive ketones under Pd(II) catalysis using HCl as ...
Scheme 5: A) Selected examples of Pd(II)-mediated quaternary carbon center synthesis by intermolecular hydroa...
Scheme 6: Selected examples of quaternary carbon center synthesis by gold(III) catalysis. This is the first r...
Scheme 7: Selected examples of inter- (A) and intramolecular (B) olefin hydroalkylations promoted by a silver...
Scheme 8: A) Intermolecular hydroalkylation of N-alkenyl β-ketoamides under Au(I) catalysis in the synthesis ...
Scheme 9: Asymmetric pyrrolidine synthesis through intramolecular hydroalkylation of α-substituted N-alkenyl ...
Scheme 10: Proposed mechanism for the chiral gold(I) complex promotion of the intermolecular olefin hydroalkyl...
Scheme 11: Selected examples of carbon quaternary center synthesis by gold and evidence of catalytic system pa...
Scheme 12: Synthesis of a spiro compound via an aza-Michael addition/olefin hydroalkylation cascade promoted b...
Scheme 13: A selected example of quaternary carbon center synthesis using an Fe(III) salt as a catalyst for th...
Scheme 14: Intermolecular hydroalkylation catalyzed by a cationic iridium complex (Fuji (2019) [47]).
Scheme 15: Generic example of an olefin hydrofunctionalization via MHAT (Shenvi (2016) [51]).
Scheme 16: The first examples of olefin hydrofunctionalization run under neutral conditions (Mukaiyama (1989) [56]...
Scheme 17: A) Aryl olefin dimerization catalyzed by vitamin B12 and triggered by HAT. B) Control experiment to...
Scheme 18: Generic example of MHAT diolefin cycloisomerization and possible competitive pathways. Shenvi (2014...
Scheme 19: Selected examples of the MHAT-promoted cycloisomerization reaction of unactivated olefins leading t...
Scheme 20: Regioselective carbocyclizations promoted by an MHAT process (Norton (2008) [76]).
Scheme 21: Selected examples of quaternary carbon centers synthetized via intra- (A) and intermolecular (B) MH...
Scheme 22: A) Proposed mechanism for the Fe(III)/PhSiH3-promoted radical conjugate addition between olefins an...
Scheme 23: Examples of cascade reactions triggered by HAT for the construction of trans-decalin backbone uniti...
Scheme 24: A) Selected examples of the MHAT-promoted radical conjugate addition between olefins and p-quinone ...
Scheme 25: A) MHAT triggered radical conjugate addition/E1cB/lactonization (in some cases) cascade between ole...
Scheme 26: A) Spirocyclization promoted by Fe(III) hydroalkylation of unactivated olefins. B) Simplified mecha...
Scheme 27: A) Selected examples of the construction of a carbon quaternary center by the MHAT-triggered radica...
Scheme 28: Hydromethylation of unactivated olefins under iron-mediated MHAT (Baran (2015) [95]).
Scheme 29: The hydroalkylation of unactivated olefins via iron-mediated reductive coupling with hydrazones (Br...
Scheme 30: Selected examples of the Co(II)-catalyzed bicyclization of dialkenylarenes through the olefin hydro...
Scheme 31: Proposed mechanism for the bicyclization of dialkenylarenes triggered by a MHAT process (Vanderwal ...
Scheme 32: Enantioconvergent cross-coupling between olefins and tertiary halides (Fu (2018) [108]).
Scheme 33: Proposed mechanism for the Ni-catalyzed cross-coupling reaction between olefins and tertiary halide...
Scheme 34: Proposed catalytic cycles for a MHAT/Ni cross-coupling reaction between olefins and halides (Shenvi...
Scheme 35: Selected examples of the hydroalkylation of olefins by a dual catalytic Mn/Ni system (Shenvi (2019) ...
Scheme 36: A) Selected examples of quaternary carbon center synthesis by reductive atom transfer; TBC: 4-tert-...
Scheme 37: A) Selected examples of quaternary carbon centers synthetized by radical addition to unactivated ol...
Scheme 38: A) Selected examples of organophotocatalysis-mediated radical polyene cyclization via a PET process...
Scheme 39: A) Sc(OTf)3-mediated carbocyclization approach for the synthesis of vicinal quaternary carbon cente...
Scheme 40: Scope of the Lewis acid-catalyzed methallylation of electron-rich styrenes. Method A: B(C6F5)3 (5.0...
Scheme 41: The proposed mechanism for styrene methallylation (Oestreich (2019) [123]).
Free-radical cyclization approach to polyheterocycles containing pyrrole and pyridine rings
- Ivan P. Mosiagin,
- Olesya A. Tomashenko,
- Dar’ya V. Spiridonova,
- Mikhail S. Novikov,
- Sergey P. Tunik and
- Alexander F. Khlebnikov
Beilstein J. Org. Chem. 2021, 17, 1490–1498, doi:10.3762/bjoc.17.105
- competitive radical reactions. Methyl and methoxy substituents in the 2-phenyl ring (Table 2, entries 5–9) did not affect the cyclization, whereas the presence of 3- or 4-NO2-substituents (Table 2, entries 10 and 11) led to tarring of the reaction mixtures probably due to participation of the NO2 group in
- side radical reactions. The fact that this result is not related to the electron-withdrawing nature of this substituent follows from the fact that another strong EWG at the position 4, such as cyano, did not interfere with the reaction, and the product was obtained in good yield. (Table 2, entry 12
Graphical Abstract
Scheme 1: Retrosynthetic analysis of heterocycles A and B.
Figure 1: Molecular structure of compound 3a, displacement parameters are drawn at 50%.
Scheme 2: Free-radical cyclization of N-protected and N-unprotected pyrroles 1a and 2.
Scheme 3: Synthesis of 2H-pyrido[2,1-a]pyrrolo[3,4-c]isoquinolin-4-ium bromide 8.
Scheme 4: Free-radical cyclization of dihalogeno-substituted salts 9 and 12.
Figure 2: Molecular structure of compound 13, displacement parameters are drawn at 50% probability level.
Scheme 5: N-alkylation of the base 6a.
Figure 3: Molecular structure of compound 17a, displacement parameters are drawn at 50% probability level.
Scheme 6: Isomerization of compounds 17a and 18a.
Scheme 7: N-Alkylation of compounds 18a and 19.
Synthetic reactions driven by electron-donor–acceptor (EDA) complexes
- Zhonglie Yang,
- Yutong Liu,
- Kun Cao,
- Xiaobin Zhang,
- Hezhong Jiang and
- Jiahong Li
Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67
- -metal catalysts, such as in the Suzuki–Miyaura and Heck coupling reactions. Methodologies for forming different C–C bonds have recently been developed in the field of single-electron chemistry [63][64][65]. Considering that EDA-complex-initiated free-radical reactions are carried out under mild
Graphical Abstract
Scheme 1: The electron transfer process in EDA complexes.
Scheme 2: Synthesis of benzo[b]phosphorus oxide 3 initiated by an EDA complex.
Scheme 3: Mechanism of the synthesis of quinoxaline derivative 7.
Scheme 4: Synthesis of imidazole derivative 10 initiated by an EDA complex.
Scheme 5: Synthesis of sulfamoylation product 12 initiated by an EDA complex.
Scheme 6: Mechanism of the synthesis of sulfamoylation product 12.
Scheme 7: Synthesis of indole derivative 22 initiated by an EDA complex.
Scheme 8: Synthesis of perfluoroalkylated pyrimidines 26 initiated by an EDA complex.
Scheme 9: Synthesis of phenanthridine derivative 29 initiated by an EDA complex.
Scheme 10: Synthesis of cis-tetrahydroquinoline derivative 32 initiated by an EDA complex.
Scheme 11: Mechanism of the synthesis of cis-tetrahydroquinoline derivative 32.
Scheme 12: Synthesis of phenanthridine derivative 38 initiated by an EDA complex.
Scheme 13: Synthesis of spiropyrroline derivative 40 initiated by an EDA complex.
Scheme 14: Synthesis of benzothiazole derivative 43 initiated by an EDA complex.
Scheme 15: Synthesis of perfluoroalkyl-s-triazine derivative 45 initiated by an EDA complex.
Scheme 16: Synthesis of indoline derivative 47 initiated by an EDA complex.
Scheme 17: Mechanism of the synthesis of spirocyclic indoline derivative 47.
Scheme 18: Synthesis of cyclobutane product 50 initiated by an EDA complex.
Scheme 19: Mechanism of the synthesis of spirocyclic indoline derivative 50.
Scheme 20: Synthesis of 1,3-oxazolidine compound 59 initiated by an EDA complex.
Scheme 21: Synthesis of trifluoromethylated product 61 initiated by an EDA complex.
Scheme 22: Synthesis of indole alkylation product 64 initiated by an EDA complex.
Scheme 23: Synthesis of perfluoroalkylation product 67 initiated by an EDA complex.
Scheme 24: Synthesis of hydrotrifluoromethylated product 70 initiated by an EDA complex.
Scheme 25: Synthesis of β-trifluoromethylated alkyne product 71 initiated by an EDA complex.
Scheme 26: Mechanism of the synthesis of 2-phenylthiophene derivative 74.
Scheme 27: Synthesis of allylated product 80 initiated by an EDA complex.
Scheme 28: Synthesis of trifluoromethyl-substituted alkynyl product 84 initiated by an EDA complex.
Scheme 29: Synthesis of dearomatized fluoroalkylation product 86 initiated by an EDA complex.
Scheme 30: Mechanism of the synthesis of dearomatized fluoroalkylation product 86.
Scheme 31: Synthesis of C(sp3)–H allylation product 91 initiated by an EDA complex.
Scheme 32: Synthesis of perfluoroalkylation product 93 initiated by an EDA complex.
Scheme 33: Synthesis of spirocyclic indolene derivative 95 initiated by an EDA complex.
Scheme 34: Synthesis of perfluoroalkylation product 97 initiated by an EDA complex.
Scheme 35: Synthesis of alkylated indole derivative 100 initiated by an EDA complex.
Scheme 36: Mechanism of the synthesis of alkylated indole derivative 100.
Scheme 37: Synthesis of arylated oxidized indole derivative 108 initiated by an EDA complex.
Scheme 38: Synthesis of 4-ketoaldehyde derivative 111 initiated by an EDA complex.
Scheme 39: Mechanism of the synthesis of 4-ketoaldehyde derivative 111.
Scheme 40: Synthesis of perfluoroalkylated olefin 118 initiated by an EDA complex.
Scheme 41: Synthesis of alkylation product 121 initiated by an EDA complex.
Scheme 42: Synthesis of acylation product 123 initiated by an EDA complex.
Scheme 43: Mechanism of the synthesis of acylation product 123.
Scheme 44: Synthesis of trifluoromethylation product 126 initiated by an EDA complex.
Scheme 45: Synthesis of unnatural α-amino acid 129 initiated by an EDA complex.
Scheme 46: Synthesis of thioether derivative 132 initiated by an EDA complex.
Scheme 47: Synthesis of S-aryl dithiocarbamate product 135 initiated by an EDA complex.
Scheme 48: Mechanism of the synthesis of S-aryl dithiocarbamate product 135.
Scheme 49: Synthesis of thioether product 141 initiated by an EDA complex.
Scheme 50: Mechanism of the synthesis of borate product 144.
Scheme 51: Synthesis of boronation product 148 initiated by an EDA complex.
Scheme 52: Synthesis of boration product 151 initiated by an EDA complex.
Scheme 53: Synthesis of boronic acid ester derivative 154 initiated by an EDA complex.
Scheme 54: Synthesis of β-azide product 157 initiated by an EDA complex.
Scheme 55: Decarboxylation reaction initiated by an EDA complex.
Scheme 56: Synthesis of amidated product 162 initiated by an EDA complex.
Scheme 57: Synthesis of diethyl phenylphosphonate 165 initiated by an EDA complex.
Scheme 58: Mechanism of the synthesis of diethyl phenylphosphonate derivative 165.
Scheme 59: Synthesis of (Z)-2-iodovinyl phenyl ether 168 initiated by an EDA complex.
Scheme 60: Mechanism of the synthesis of (Z)-2-iodovinyl phenyl ether derivative 168.
Scheme 61: Dehalogenation reaction initiated by an EDA complex.
Helicene synthesis by Brønsted acid-catalyzed cycloaromatization in HFIP [(CF3)2CHOH]
- Takeshi Fujita,
- Noriaki Shoji,
- Nao Yoshikawa and
- Junji Ichikawa
Beilstein J. Org. Chem. 2021, 17, 396–403, doi:10.3762/bjoc.17.35
- reactions (Scheme 1a). Diels–Alder (Scheme 1b) [15] and radical reactions (Scheme 1c) [16] directed toward helicene synthesis require high temperature conditions even for low to moderate yields. Olefin metathesis (Scheme 1d) [17] and alkyne trimerization (Scheme 1e) [18][19] require the use of expensive
Graphical Abstract
Scheme 1: Conventional methods for the synthesis of helicenes.
Scheme 2: Brønsted acid-catalyzed cycloaromatization of biaryls bearing an acetal moiety.
Scheme 3: Two strategies for the helicene synthesis via Suzuki–Miyaura coupling/cycloaromatization sequence.
Scheme 4: Synthesis of (a) [5]helicene and (b) [6]helicene.
Scheme 5: Synthesis of helicenes with double helical structures.
Scheme 6: Synthesis of hetero[4]-, [5]-, and [6]helicenes.
A novel and robust heterogeneous Cu catalyst using modified lignosulfonate as support for the synthesis of nitrogen-containing heterocycles
- Bingbing Lai,
- Meng Ye,
- Ping Liu,
- Minghao Li,
- Rongxian Bai and
- Yanlong Gu
Beilstein J. Org. Chem. 2020, 16, 2888–2902, doi:10.3762/bjoc.16.238
- , ring-closing, metathesis, cycloadditions, radical reactions and microwave-assisted reactions [38][39][40]. In this work, we attempt to develop a greener, simpler, more efficient and recyclable system to synthesize arylpyridine derivatives. Initially, the reaction of acetophenone (5a) and 1,3
Graphical Abstract
Figure 1: Schematic illustration for the preparation of the catalyst in this work.
Figure 2: FTIR spectra of LS, LS-FAS, and LS-FAS-Cu.
Figure 3: Thermogravimetric weight loss of the obtained materials LS-FAS and LS-FAS-Cu.
Figure 4: FSEM imagine of LS-FAS-Cu in different scale label a) 1 μm, b) 200 nm; FTEM images of LS-FAS-Cu in ...
Figure 5: XPS spectra of LS-FAS-Cu in the regions of C 1s, O 1s, Cu 2p3/2 and Cu LMM (inset).
Scheme 1: Substrate scope of LS-FAS-Cu catalyzed three-component reactions of 4-aminoindoles, alkynes and ald...
Figure 6: Recyclability of LS-FAS-Cu, LS-FM-Cu and Resin-Cu in the reaction between compounds 1a, 2a and 3a.
When metal-catalyzed C–H functionalization meets visible-light photocatalysis
- Lucas Guillemard and
- Joanna Wencel-Delord
Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147
- previous functionalization, thus considerably reduce waste generation and a number of synthetic steps. In parallel, transformations involving photoredox catalysis promote radical reactions in the absence of radical initiators. They are conducted under particularly mild conditions while using the visible
Graphical Abstract
Figure 1: Concept of dual synergistic catalysis.
Figure 2: Classification of catalytic systems involving two catalysts.
Figure 3: General mechanism for the dual nickel/photoredox catalytic system.
Figure 4: General mechanisms for C–H activation catalysis involving different reoxidation strategies.
Figure 5: Indole synthesis via dual C–H activation/photoredox catalysis.
Figure 6: Proposed mechanism for the indole synthesis via dual catalysis.
Figure 7: Oxidative Heck reaction on arenes via the dual catalysis.
Figure 8: Proposed mechanism for the Heck reaction on arenes via dual catalysis.
Figure 9: Oxidative Heck reaction on phenols via the dual catalysis.
Figure 10: Proposed mechanism for the Heck reaction on phenols via dual catalysis.
Figure 11: Carbazole synthesis via dual C–H activation/photoredox catalysis.
Figure 12: Proposed mechanism for the carbazole synthesis via dual catalysis.
Figure 13: Carbonylation of enamides via the dual C–H activation/photoredox catalysis.
Figure 14: Proposed mechanism for carbonylation of enamides via dual catalysis.
Figure 15: Annulation of benzamides via the dual C–H activation/photoredox catalysis.
Figure 16: Proposed mechanism for the annulation of benzamides via dual catalysis.
Figure 17: Synthesis of indoles via the dual C–H activation/photoredox catalysis.
Figure 18: Proposed mechanism for the indole synthesis via dual catalysis.
Figure 19: General concept of dual catalysis merging C–H activation and photoredox catalysis.
Figure 20: The first example of dual catalysis merging C–H activation and photoredox catalysis.
Figure 21: Proposed mechanism for the C–H arylation with diazonium salts via dual catalysis.
Figure 22: Dual catalysis merging C–H activation/photoredox using diaryliodonium salts.
Figure 23: Direct arylation via the dual catalytic system reported by Xu.
Figure 24: Direct arylation via dual catalytic system reported by Balaraman.
Figure 25: Direct arylation via dual catalytic system reported by Guo.
Figure 26: C(sp3)–H bond arylation via the dual Pd/photoredox catalytic system.
Figure 27: Acetanilide derivatives acylation via the dual C–H activation/photoredox catalysis.
Figure 28: Proposed mechanism for the C–H acylation with α-ketoacids via dual catalysis.
Figure 29: Acylation of azobenzenes via the dual catalysis C–H activation/photoredox.
Figure 30: C2-acylation of indoles via the dual C–H activation/photoredox catalysis.
Figure 31: Proposed mechanism for the C2-acylation of indoles with aldehydes via dual catalysis.
Figure 32: C2-acylation of indoles via the dual C–H activation/photoredox catalysis.
Figure 33: Perfluoroalkylation of arenes via the dual C–H activation/photoredox catalysis.
Figure 34: Proposed mechanism for perfluoroalkylation of arenes via dual catalysis.
Figure 35: Sulfonylation of 1-naphthylamides via the dual C–H activation/photoredox catalysis.
Figure 36: Proposed mechanism for sulfonylation of 1-naphthylamides via dual catalysis.
Figure 37: meta-C–H Alkylation of arenes via visible-light metallaphotocatalysis.
Figure 38: Alternative procedure for meta-C–H alkylation of arenes via metallaphotocatalysis.
Figure 39: Proposed mechanism for meta-C–H alkylation of arenes via metallaphotocatalysis.
Figure 40: C–H borylation of arenes via visible-light metallaphotocatalysis.
Figure 41: Proposed mechanism for C–H borylation of arenes via visible-light metallaphotocatalysis.
Figure 42: Undirected C–H aryl–aryl cross coupling via dual gold/photoredox catalysis.
Figure 43: Proposed mechanism for the undirected C–H aryl–aryl cross-coupling via dual catalysis.
Figure 44: Undirected C–H arylation of (hetero)arenes via dual manganese/photoredox catalysis.
Figure 45: Proposed mechanism for the undirected arylation of (hetero)arenes via dual catalysis.
Figure 46: Photoinduced C–H arylation of azoles via copper catalysis.
Figure 47: Photo-induced C–H chalcogenation of azoles via copper catalysis.
Figure 48: Decarboxylative C–H adamantylation of azoles via dual cobalt/photoredox catalysis.
Figure 49: Proposed mechanism for the C–H adamantylation of azoles via dual catalysis.
Figure 50: General mechanisms for the “classical” (left) and Cu-free variant (right) Sonogoshira reaction.
Figure 51: First example of a dual palladium/photoredox catalysis for Sonogashira-type couplings.
Figure 52: Arylation of terminal alkynes with diazonium salts via dual gold/photoredox catalysis.
Figure 53: Proposed mechanism for the arylation of terminal alkynes via dual catalysis.
Figure 54: C–H Alkylation of alcohols promoted by H-atom transfer (HAT).
Figure 55: Proposed mechanism for the C–H alkylation of alcohols promoted by HAT.
Figure 56: C(sp3)–H arylation of latent nucleophiles promoted by H-atom transfer.
Figure 57: Proposed mechanism for the C(sp3)–H arylation of latent nucleophiles promoted by HAT.
Figure 58: Direct α-arylation of alcohols promoted by H-atom transfer.
Figure 59: Proposed mechanism for the direct α-arylation of alcohols promoted by HAT.
Figure 60: C–H arylation of amines via dual Ni/photoredox catalysis.
Figure 61: Proposed mechanism for the C–H arylation of amines via dual Ni/photoredox catalysis.
Figure 62: C–H functionalization of nucleophiles via excited ketone/nickel dual catalysis.
Figure 63: Proposed mechanism for the C–H functionalization enabled by excited ketones.
Figure 64: Selective sp3–sp3 cross-coupling promoted by H-atom transfer.
Figure 65: Proposed mechanism for the selective sp3–sp3 cross-coupling promoted by HAT.
Figure 66: Direct C(sp3)–H acylation of amines via dual Ni/photoredox catalysis.
Figure 67: Proposed mechanism for the C–H acylation of amines via dual Ni/photoredox catalysis.
Figure 68: C–H hydroalkylation of internal alkynes via dual Ni/photoredox catalysis.
Figure 69: Proposed mechanism for the C–H hydroalkylation of internal alkynes.
Figure 70: Alternative procedure for the C–H hydroalkylation of ynones, ynoates, and ynamides.
Figure 71: Allylic C(sp3)–H activation via dual Ni/photoredox catalysis.
Figure 72: Proposed mechanism for the allylic C(sp3)–H activation via dual Ni/photoredox catalysis.
Figure 73: Asymmetric allylation of aldehydes via dual Cr/photoredox catalysis.
Figure 74: Proposed mechanism for the asymmetric allylation of aldehydes via dual catalysis.
Figure 75: Aldehyde C–H functionalization promoted by H-atom transfer.
Figure 76: Proposed mechanism for the C–H functionalization of aldehydes promoted by HAT.
Figure 77: Direct C–H arylation of strong aliphatic bonds promoted by HAT.
Figure 78: Proposed mechanism for the C–H arylation of strong aliphatic bonds promoted by HAT.
Figure 79: Direct C–H trifluoromethylation of strong aliphatic bonds promoted by HAT.
Figure 80: Proposed mechanism for the C–H trifluoromethylation of strong aliphatic bonds.
Photoredox-catalyzed silyldifluoromethylation of silyl enol ethers
- Vyacheslav I. Supranovich,
- Vitalij V. Levin and
- Alexander D. Dilman
Beilstein J. Org. Chem. 2020, 16, 1550–1553, doi:10.3762/bjoc.16.126
- basic conditions required to activate inert C–Si bonds with the generation of carbanionic species. On the other hand, radical reactions offer different synthetic opportunities originating from the neutral character of the intermediates [6][7] and, accordingly, radical fluoroalkylation processes have
Graphical Abstract
Scheme 1: Reactions of (bromodifluoromethyl)trimethylsilane (1).
Scheme 2: Optimization studies. Yield determined by 19F NMR spectroscopy using an internal standard.
Figure 1: Reaction of silyl enol ethers. Yields refer to isolated yields. aReaction time 24 h; b1.0 equiv of ...
Scheme 3: Proposed mechanism of the fluoroalkylation reaction.
Copper catalysis with redox-active ligands
- Agnideep Das,
- Yufeng Ren,
- Cheriehan Hessin and
- Marine Desage-El Murr
Beilstein J. Org. Chem. 2020, 16, 858–870, doi:10.3762/bjoc.16.77
- phenols, ketones and 1,3-dienes (Scheme 6) [27]. C–C bond formation Complexes of radical and redox-active ligands with transition metals are known to be able to promote radical reactions through single-electron transfer (SET) processes [28]. Expanding on the research area pioneered by Wieghardt and
Graphical Abstract
Scheme 1: Copper complexes with amidophenolate type benzoxazole ligands for alcohol oxidations.
Scheme 2: Copper-catalyzed aerobic oxidation of alcohols and representative substrate scope.
Scheme 3: Introduction of H-bonding network in the ligand coordination sphere.
Scheme 4: Well-defined isatin copper complexes.
Scheme 5: Catalyst control in the biomimetic phenol ortho-oxidation.
Scheme 6: Structural diversity accessible by direct functionalization.
Scheme 7: Copper-catalyzed trifluoromethylation of heteroaromatics with redox-active iminosemiquinone ligands....
Scheme 8: Reversal of helical chirality upon redox stimuli and enantioselective Michael addition with a redox...
Scheme 9: Interaction of guanidine-copper catalyst with oxygen and representative coupling products. a4 mol %...
Scheme 10: Access to 1,2-oxy-aminoarenes by copper-catalyzed phenol–amine coupling.
Scheme 11: Copper-catalyzed aziridination through molecular spin catalysis with redox-active iminosemiquinone ...
Scheme 12: Nitrogen-group and carbon-group transfer in copper-catalyzed aziridination and cyclopropanation thr...
Controlling alkyne reactivity by means of a copper-catalyzed radical reaction system for the synthesis of functionalized quaternary carbons
- Goki Hirata,
- Yu Yamane,
- Naoya Tsubaki,
- Reina Hara and
- Takashi Nishikata
Beilstein J. Org. Chem. 2020, 16, 502–508, doi:10.3762/bjoc.16.45
- ][14][15][16]. Recently, we have prepared quaternary carbon centers via radical reactions by using α-bromocarbonyl compounds (a tertiary alkyl source) and olefins or heteroatoms in the presence of a copper catalyst [17][18][19]. During our studies, we found that combinations of alkynes and tertiary
Graphical Abstract
Scheme 1: Reaction modes of alkyne.
Figure 1: Substrate scope of 1 and 2. aConducted at 80 °C for 24 h in MeCN with CuBr (10 mol %), 1,10-Phen (2...
Scheme 2: Proposed mechanism.
Scheme 3: Control experiment.
Scheme 4: Reaction of 2a and 4a.
Figure 2: Substrate scope of 2 and 4. aConducted at 100 °C for 20 h in 1,4-dioxane with CuI (10 mol %), 1,10-...
Vicinal difunctionalization of alkenes by four-component radical cascade reaction of xanthogenates, alkenes, CO, and sulfonyl oxime ethers
- Shuhei Sumino,
- Takahide Fukuyama,
- Mika Sasano,
- Ilhyong Ryu,
- Antoine Jacquet,
- Frédéric Robert and
- Yannick Landais
Beilstein J. Org. Chem. 2019, 15, 1822–1828, doi:10.3762/bjoc.15.176
- a single operation [1][2][3][4][5]. Needless to say, the contribution by radical chemistry is not trivial [5][6][7]. While alkenes and alkynes have served as efficient radical donor/acceptor type C2 synthons in multicomponent radical reactions, CO and isonitriles were shown to react as donor
Graphical Abstract
Scheme 1: Concept: Alkene difuctionalization by four-component radical reaction using xanthates, alkenes, CO ...
Figure 1: Vicinal difunctionalization of alkenes by four-component radical cascade reaction using xanthogenat...
Figure 2: Proposed radical chain mechanism.
Oxidative radical ring-opening/cyclization of cyclopropane derivatives
- Yu Liu,
- Qiao-Lin Wang,
- Zan Chen,
- Cong-Shan Zhou,
- Bi-Quan Xiong,
- Pan-Liang Zhang,
- Chang-An Yang and
- Quan Zhou
Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23
- a nucleophilic group to obtain the product L (path III). Free radical reactions have flourished and became a powerful tool in organic synthesis [32][33][34][35][36][37][38]. With the significant potential, this strategy has captured the human’s attention and solved considerable problems in the past
Graphical Abstract
Scheme 1: The oxidative radical ring-opening/cyclization of cyclopropane derivatives.
Scheme 2: Mn(OAc)3-mediated oxidative radical ring-opening and cyclization of MCPs with malonates.
Scheme 3: Mn(III)-mediated oxidative radical ring-opening and cyclization of MCPs with 1,3-dicarbonyl compoun...
Scheme 4: Heat-promoted ring-opening/cyclization of MCPs with elemental chalgogens.
Scheme 5: Copper(II) acetate-mediated oxidative radical ring-opening and cyclization of MCPs with diphenyl di...
Scheme 6: AIBN-promoted oxidative radical ring-opening and cyclization of MCPs with benzenethiol.
Scheme 7: AIBN-mediated oxidative radical ring-opening and cyclization of MCPs with diethyl phosphites.
Scheme 8: Organic-selenium induced radical ring-opening and cyclization of MCPs derivatives (cyclopropylaldeh...
Scheme 9: Copper(I)-catalyzed oxidative radical trifluoromethylation/ring-opening/cyclization of MCPs with To...
Scheme 10: Ag(I)-mediated trifluoromethylthiolation/ring-opening/cyclization of MCPs with AgSCF3.
Scheme 11: oxidative radical ring-opening and cyclization of MCPs with α-C(sp3)-–H of ethers.
Scheme 12: Oxidative radical ring-opening and cyclization of MCPs with aldehydes.
Scheme 13: Cu(I) or Fe(II)-catalyzed oxidative radical trifluoromethylation/ring-opening/cyclization of MCPs d...
Scheme 14: Rh(II)-catalyzed oxidative radical ring-opening and cyclization of MCPs.
Scheme 15: Ag(I)-catalyzed oxidative radical amination/ring-opening/cyclization of MCPs derivatives.
Scheme 16: Heating-promoted radical ring-opening and cyclization of MCP derivatives (arylvinylidenecyclopropan...
Scheme 17: Bromine radical-mediated ring-opening of alkylidenecyclopropanes.
Scheme 18: Fluoroalkyl (Rf) radical-mediated ring-opening of MCPs.
Scheme 19: Visible-light-induced alkylation/ring-opening/cyclization of cyclopropyl olefins with bromides.
Scheme 20: Mn(III)-mediated ring-opening and [3 + 3]-annulation of cyclopropanols and vinyl azides.
Scheme 21: Ag(I)-catalyzed oxidative ring-opening of cyclopropanols with quinones.
Scheme 22: Ag(I)-catalyzed oxidative ring-opening of cyclopropanols with heteroarenes.
Scheme 23: Cu(I)-catalyzed oxidative ring-opening/trifluoromethylation of cyclopropanols.
Scheme 24: Cu(I)-catalyzed oxidative ring-opening and trifluoromethylation/trifluoromethylthiolation of cyclop...
Scheme 25: Ag(I)-mediated oxidative ring-opening/fluorination of cyclopropanols with Selectfluor.
Scheme 26: Photocatalyzed ring-opening/fluorination of cyclopropanols with Selectfluor.
Scheme 27: Na2S2O8-promoted ring-opening/alkynylation of cyclopropanols with EBX.
Scheme 28: Ag(I)-catalyzed ring-opening and chlorination of cyclopropanols with aldehydes.
Scheme 29: Ag(I)-catalyzed ring-opening/alkynylation of cyclopropanols with EBX.
Scheme 30: Na2S2O8-promoted ring-opening/alkylation of cyclopropanols with acrylamides.
Scheme 31: Cyclopropanol ring-opening initiated tandem cyclization with acrylamides or 2-isocyanobiphenyls.
Scheme 32: Ag(II)-mediated oxidative ring-opening/fluorination of cyclopropanols with AgF2.
Scheme 33: Cu(II)-catalyzed ring-opening/fluoromethylation of cyclopropanols with sulfinate salts.
Scheme 34: Cu(II)-catalyzed ring-opening/sulfonylation of cyclopropanols with sulfinate salts.
Scheme 35: Na2S2O8-promoted ring-opening/arylation of cyclopropanols with propiolamides.
Scheme 36: The ring-opening and [3 + 2]-annulation of cyclopropanols with α,β-unsaturated aldehydes.
Scheme 37: Cu(II)-catalyzed ring-opening/arylation of cyclopropanols with aromatic nitrogen heterocyles.
Scheme 38: Ag(I)-catalyzed ring-opening and difluoromethylthiolation of cyclopropanols with PhSO2SCF2H.
Scheme 39: Ag(I)-catalyzed ring-opening and acylation of cyclopropanols with aldehydes.
Scheme 40: Aerobic oxidation ring-opening of cyclopropanols for the synthesis of 2-oxyranyl ketones.
Scheme 41: Aerobic oxidation ring-opening of cyclopropanols for the synthesis of linear enones.
Scheme 42: Aerobic oxidation ring-opening of cyclopropanols for the synthesis of metabolite.
Hypervalent iodine compounds for anti-Markovnikov-type iodo-oxyimidation of vinylarenes
- Igor B. Krylov,
- Stanislav A. Paveliev,
- Mikhail A. Syroeshkin,
- Alexander A. Korlyukov,
- Pavel V. Dorovatovskii,
- Yan V. Zubavichus,
- Gennady I. Nikishin and
- Alexander O. Terent’ev
Beilstein J. Org. Chem. 2018, 14, 2146–2155, doi:10.3762/bjoc.14.188
- versatile leaving group for further transformations. The involvement of the iodine in the radical reactions of styrenes is complicated by the fact that unsaturated compounds readily undergo electrophilic iodination with the addition of an external nucleophile [61][62]. The oxidants used for the preparation
Graphical Abstract
Scheme 1: Difunctionalization of double C=C bond with the formation of C–O and C–I bonds.
Scheme 2: Iodo-oxyimidation of styrenes 1a–k with preparation of products 3aa–ka, 3ab–db, 3fb, 3hb, and 3kb.
Figure 1: Scope of the iodo-oxyimidation of vinylarenes with I2/PhI(OAc)2 system. Reaction conditions: vinyla...
Figure 2: Molecular structure of 3ca. Atoms are presented as anisotropic displacement parameters (ADP) ellips...
Scheme 3: The proposed mechanism of iodo-oxyimidation of styrene (1a) using the NHPI/I2/PhI(OAc)2 system with...
Figure 3: CV curves of styrene (1a, purple), NHPI (2a, red), I2 (blue) and PhI(OAc)2 (green) in 0.1 M n-Bu4NBF...
Scheme 4: Gram-scale synthesis of compound 3aa.
Scheme 5: Synthetic utility of the iodo-oxyimides 3aa and 3ab.
Aminomethylation/hydrogenolysis as an alternative to direct methylation of metalated isoquinolines – a novel total synthesis of the alkaloid 7-hydroxy-6-methoxy-1-methylisoquinoline
- Benedikt C. Melzer,
- Jan G. Felber and
- Franz Bracher
Beilstein J. Org. Chem. 2018, 14, 130–134, doi:10.3762/bjoc.14.8
- with methylmagnesium bromide [17], and direct methylation using radical reactions [9][18][19]. Hence, we searched for a more viable method for the introduction of the methyl group. A prerequisite was that the organometallic intermediate should be trapped by an electrophile which could later be
Graphical Abstract
Figure 1: Previously published total syntheses of alkaloid 1 [11,12].
Scheme 1: Total synthesis of alkaloid 1 via direct ring metalation and methylation.
Scheme 2: Total synthesis of alkaloid 1 via the aminomethyl intermediate 5 and selectivity’s found in debenzy...
Kinetic analysis of mechanoradical formation during the mechanolysis of dextran and glycogen
- Naoki Doi,
- Yasushi Sasai,
- Yukinori Yamauchi,
- Tetsuo Adachi,
- Masayuki Kuzuya and
- Shin-ichi Kondo
Beilstein J. Org. Chem. 2017, 13, 1174–1183, doi:10.3762/bjoc.13.116
- generated by subsequent radical reactions such as hydrogen abstraction and/or recombination after polymer main-chain scission, could be assigned to alkoxylalkyl-type radicals at the C1 and acylalkyl-type radicals at the C2 and/or C3 positions. Therefore, these observed mechanoradicals were mid-chain
Graphical Abstract
Figure 1: Structures of discrete mechanoradicals and the reaction sequence for their formation from cellulose ...
Figure 2: Schematic structure of amylose, dextran and glycogen.
Figure 3: Progressive changes in observed ESR spectra of fractured amylose [5], Dx, and Gly, together with simul...
Figure 4: Schematic representation of bond cleavage at α-1,4- and α-1,6-bonds.
Figure 5: ESR spectrum of fractured sample of Dx and TCNE (a) before and (b) after visible-light irradiation.
Figure 6: Component spectra of the simulated ESR spectra.
Figure 7: Progressive changes in the intensity of component spectra corresponding to the simulated spectra of...
Figure 8: Changes in Dx molecular-weight distribution (MWD) during vibratory milling.
Figure 9: Changes in Dx weight-average molecular weight (Mw) during vibratory milling.
Figure 10: Change in Gly particle diameter during vibratory milling.
Chemoselective synthesis of diaryl disulfides via a visible light-mediated coupling of arenediazonium tetrafluoroborates and CS2
- Jing Leng,
- Shi-Meng Wang and
- Hua-Li Qin
Beilstein J. Org. Chem. 2017, 13, 903–909, doi:10.3762/bjoc.13.91
- and to minimize the formation of the byproducts was conducted. As recently surveyed, photoredox catalysts are widely employed for the generation of radicals for diverse radical reactions [19]. Further, the application of aryl radicals generated from aryldiazonium salts under visible light irradiation
Graphical Abstract
Scheme 1: Chemoselective assembly of diaryl disulfides.
Scheme 2: A plausible reaction mechanism.
The reductive decyanation reaction: an overview and recent developments
- Jean-Marc R. Mattalia
Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30
- radical recombination with the nickel species produce 66. Finally, an elimination of Ar-H closes the catalytic cycle. A similar mechanism was proposed with method B. Radical reactions This part is related to radical reactions not involving alkali metals and focuses on the reduction of malononitriles and
Graphical Abstract
Scheme 1: Mechanism for the reduction under metal dissolving conditions.
Scheme 2: Example of decyanation in metal dissolving conditions coupled with deprotection [30]. TBDMS = tert-buty...
Scheme 3: Preparation of α,ω-dienes [18,33].
Scheme 4: Cyclization reaction using a radical probe [18].
Scheme 5: Synthesis of (±)-xanthorrhizol (8) [39].
Scheme 6: Mechanism for the reduction of α-aminonitriles by hydride donors.
Scheme 7: Synthesis of phenanthroindolizidines and phenanthroquinolizidines [71].
Scheme 8: Two-step synthesis of 5-unsubstituted pyrrolidines (25 examples and 1 synthetic application, see be...
Scheme 9: Synthesis of (±)-isoretronecanol 19. DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene [74].
Scheme 10: Proposed mechanism with 14a for the NaBH4 induced decyanation reaction (“BH3” = BH3·THF) [74].
Scheme 11: Reductive decyanation by a sodium hydride–iodide composite (26 examples) [81].
Scheme 12: Proposed mechanism for the reduction by NaH [81].
Scheme 13: Reductive decyanation catalyzed by nickel nanoparticles. Yields are given in weight % from GC–MS da...
Scheme 14: Decyanation of 2-cyanobenzo[b]thiophene [87].
Scheme 15: Simplified pathways involved in transition-metal-promoted reductive decyanations [93,95].
Scheme 16: Fe-catalyzed reductive decyanation. Numbers in square brackets represent turnover numbers. The TONs...
Scheme 17: Rh-catalyzed reductive decyanation of aryl nitriles (18 examples, 2 synthetic applications) [103].
Scheme 18: Rh-catalyzed reductive decyanation of aliphatic nitriles (15 examples, one synthetic application) [103].
Scheme 19: Ni-catalyzed reductive decyanation (method A: 28 examples and 2 synthetic applications; method B: 3...
Scheme 20: Reductive decyanation catalyzed by the nickel complex 58 (method A, 14 examples, yield ≥ 20% and 1 ...
Scheme 21: Proposed catalytic cycle for the nickel complex 58 catalyzed decyanation (method A). Only the cycle...
Scheme 22: Synthesis of bicyclic lactones [119,120].
Scheme 23: Reductive decyanation of malononitriles and cyanoacetates using NHC-boryl radicals (9 examples). Fo...
Scheme 24: Proposed mechanism for the reduction by NHC-boryl radicals. The other possible pathway (addition of ...
Scheme 25: Structures of organic electron-donors. Only the major Z isomer of 80 is shown [125,127].
Scheme 26: Reductive decyanation of malononitriles and cyanoacetates using organic electron-donors (method A, ...
Scheme 27: Photoreaction of dibenzylmalononitrile with 81 [128].
Scheme 28: Examples of decyanation promoted in acid or basic media [129,131,134,135].
Scheme 29: Mechanism proposed for the base-induced reductive decyanation of diphenylacetonitriles [136].
Scheme 30: Reductive decyanation of triarylacetonitriles [140].
Silyl-protective groups influencing the reactivity and selectivity in glycosylations
- Mikael Bols and
- Christian Marcus Pedersen
Beilstein J. Org. Chem. 2017, 13, 93–105, doi:10.3762/bjoc.13.12
- stereoselectivity has been demonstrated in radical reactions, however, with the twist that stereoselectivity here is opposite. The reduction of the selenoglycosides (analogues to 20) with tributyltin deuteride gave predominantly deuterium in the β-position for silylated derivatives in the 1C4 conformation, because
Graphical Abstract
Figure 1: Silicon-protective groups typically used in carbohydrate chemistry.
Scheme 1: Glycosylation with sulfoxide 1.
Scheme 2: Glycosylation with imidate 4.
Scheme 3: Glycosylation with thioglycoside 7.
Scheme 4: In situ formation of a silylated lactosyl iodide for the synthesis of α-lactosylceramide.
Figure 2: Comparison of the reactivity of glycosyl donors with the pKa of the corresponding piperidinium ions....
Figure 3: Conformational change induced by bulky vicinal protective groups such as TBS, TIPS and TBDPS. The v...
Scheme 5: An example of a “one pot one addition” glycosylation, where 3 glucosyl donors are mixed with 2.1 eq...
Scheme 6: Superarmed-armed glycosylation with thioglycoside 34.
Scheme 7: One-pot double glycosylation with the conformationally armed thioglycoside 37.
Scheme 8: Superarmed-armed glycosylation with thioglycoside 41.
Figure 4: Donors disarmed by the di-tert-butylsilylene protective group.
Figure 5: The influence of a 3,6-O-tethering on anomeric reactivity and glycosylation selectivity. The α-thio...
Scheme 9: Regio- and stereoselective glycosylation using the superarmed thioglycoside donor 20.
Scheme 10: Superarmed donors used for C-arylation and the dependence of the size of the silylethers on the ste...
Scheme 11: β-Selective glucosylation with TIPS-protected glucosyl donors. The α-face is shielded by the bulky ...
Scheme 12: β-Selective rhamnosylation with a conformationally inverted donor.
Scheme 13: α-Selective galactosylation with DTBS-protected galactosyl donors.
Scheme 14: β-Selective arabinofuranosylation with a DTBS-protected donor.
Scheme 15: α-Selective glycosylation with a TIPDS-protected glucal donor.
Scheme 16: Highly β-selective glucuronylation using a 2,4-DTBS-tethered donor.
Diastereoselective anodic hetero- and homo-coupling of menthol-, 8-methylmenthol- and 8-phenylmenthol-2-alkylmalonates
- Matthias C. Letzel,
- Hans J. Schäfer and
- Roland Fröhlich
Beilstein J. Org. Chem. 2017, 13, 33–42, doi:10.3762/bjoc.13.5
- of malonic acid derivatives [33]. In the literature, there are only a few examples where menthol auxiliaries have been used to control the stereochemistry in radical reactions [34]. In first experiments using (−)-menthol (1) as a chiral auxiliary we observed a low but nevertheless promising
Graphical Abstract
Figure 1: Menthol auxiliaries 1–4 used in the following anodic coupling reactions.
Scheme 1: Synthesis of carboxylic acids 13a/b–18a/b.
Scheme 2: (a) Preparation of benzyl 2-isopropylmalonate (5) and (b) preparation of benzyl 2-tert-butylmalonat...
Scheme 3: Coelectrolysis (hetero-coupling) of carboxylic acids 13–17 with 3,3-dimethylbutyric acid (20).
Figure 2: Crystal structure of the minor diastereomer 23b.
Figure 3: Cyclic voltammograms of the malonic derivatives 15a/b, 16a/b and 18a/b (scan rate: 500 mA/s, solven...
Scheme 4: Homo-coupling of carboxylic acids 13a/b–16a/b to diesters 26a/b/c–29a/b/c (n.d.: not determined).
Figure 4: Crystal structure of major diastereomer 28a.
Figure 5: Crystal structure of major diastereomer 29a.
Figure 6: Discrimination of diastereomeric faces in the menthol substituted radical A and in the 8-phenylment...
Scheme 5: Reductive cleavage of 30a–c to 8-phenylmenthol (3) and 31a–c.
A versatile route to polythiophenes with functional pendant groups using alkyne chemistry
- Xiao Huang,
- Li Yang,
- Rikard Emanuelsson,
- Jonas Bergquist,
- Maria Strømme,
- Martin Sjödin and
- Adolf Gogoll
Beilstein J. Org. Chem. 2016, 12, 2682–2688, doi:10.3762/bjoc.12.265
- cross-coupling reactions, cycloaddition reactions, radical reactions and reductive addition reactions. A terminal alkyne can also react as nucleophile or serve as synthon for pyrrole rings [24][25]. Thus we here fuse the rich alkyne chemistry to the EDOT backbone, resulting in a novel EDOT derivative
Graphical Abstract
Scheme 1: Previous and present EDOT functionalization routes.
Scheme 2: The synthetic route from glycidol to pyEDOT (3).
Scheme 3: The synthetic route from D-mannitol diketal to eEDOT 8 and TMS-eEDOT 8’.
Scheme 4: New EDOT derivatives 9–13 accessible from pyEDOT with bromo-pendant group precursors via Sonogashir...
Figure 1: CVs of electrochemical polymerization of (a) pyEDOT 3 and (b) EDOT in MeCN solution with 0.1 M TEAPF...
Figure 2: CVs of electrochemical polymerization of (a) pyEDOT-DeT (9), (b) pyEDOT-AQ (12) and (c) pyEDOT-MVPF...
Methylenelactide: vinyl polymerization and spatial reactivity effects
- Judita Britner and
- Helmut Ritter
Beilstein J. Org. Chem. 2016, 12, 2378–2389, doi:10.3762/bjoc.12.232
- also shows additional postulated radical reactions including the formation of a bicyclic lactide radical to initiate the main polymerization. Since the spontaneous homolytically C–H cleavage may represent the first step in the reaction cascade, theoretical calculations on a DFT level were conducted
Graphical Abstract
Figure 1: Structures of used monomers and the time-conversion plot of the corresponding free-radical polymeri...
Scheme 1: Stereospecific propagation of chiral MLA illustrating the triade formation [15].
Figure 2: Plot of log Pn versus log [In] of the polymerization of MLA with different mol % AIBN.
Scheme 2: Postulated mechanism of the self-initiation of MLA.
Figure 3: DFT-calculated C–C binding length (yellow) of (A) MLA and (B) the corresponding radical.
Figure 4: IR spectra of (A) MLA and of (B) poly(MLA) prepared by the self-initiated polymerization at 70 °C.
Figure 5: Conversion plot of the polymerization of MLA in 1,4-dioxane and DMF (cMLA = 1.8 mol L−1, cAIBN = 1....
Figure 6: UV–vis spectra of the reaction mixture with DPPH radical at the beginning (violet line, 0.23 mM) of...
Figure 7: Copolymer composition curves for the systems MLA with styrene and MMA.
Figure 8: 1H NMR spectrum of MLA with 1 equiv of thioacetic acid and 0.15 equivalents of an inhibitor 4-metho...
Scheme 3: Mechanism of RAFT polymerization [24].
Figure 9: Structures of used RAFT agents examined in the polymerization of MLA.
Figure 10: A) Kinetic plot for the RAFT copolymerization of MLA and DMA for the ratio 90/10 employing EMP. B) ...
Rearrangements of organic peroxides and related processes
- Ivan A. Yaremenko,
- Vera A. Vil’,
- Dmitry V. Demchuk and
- Alexander O. Terent’ev
Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162
- agents and initiators for free-radical reactions both in industry and in laboratory. These compounds are produced and involved in various natural and biological processes and were explored extensively as antimalarial agents, anthelmintics, and anticancer drugs. Organic peroxides, such as alkyl
Graphical Abstract
Figure 1: The named transformations considered in this review.
Scheme 1: The Baeyer–Villiger oxidation.
Scheme 2: The general mechanism of the peracid-promoted Baeyer–Villiger oxidation.
Scheme 3: General mechanism of the Lewis acid-catalyzed Baeyer–Villiger rearrangement.
Scheme 4: The theoretically studied mechanism of the BV oxidation reaction promoted by H2O2 and the Lewis aci...
Scheme 5: Proton movements in the transition states of the Baeyer–Villiger oxidation.
Scheme 6: The dependence of the course of the Baeyer–Villiger oxidation on the type of O–O-bond cleavage in t...
Scheme 7: The acid-catalyzed Baeyer–Villiger oxidation of cyclic epoxy ketones 22.
Scheme 8: Oxidation of isophorone oxide 29.
Scheme 9: Synthesis of acyl phosphate 32 from acyl phosphonate 31.
Scheme 10: Synthesis of aflatoxin B2 (36).
Scheme 11: The Baeyer–Villiger rearrangement of ketones 37 to lactones 38.
Scheme 12: Synthesis of 3,4-dimethoxybenzoic acid (40) via Baeyer–Villiger oxidation.
Scheme 13: Oxone transforms α,β-unsaturated ketones 43 into vinyl acetates 44.
Scheme 14: The Baeyer–Villiger oxidation of ketones 45 using diaryl diselenide and hydrogen peroxide.
Scheme 15: Baeyer–Villiger oxidation of (E)-2-methylenecyclobutanones.
Scheme 16: Oxidation of β-ionone (56) by H2O2/(BnSe)2 with formation of (E)-2-(2,6,6-trimethylcyclohex-1-en-1-...
Scheme 17: The mechanism of oxidation of ketones 58a–f by hydrogen peroxide in the presence of arsonated polys...
Scheme 18: Oxidation of ketone (58b) by H2O2 to 6-methylcaprolactone (59b) catalyzed by Pt complex 66·BF4.
Scheme 19: Oxidation of ketones 67 with H2O2 in the presence of [(dppb}Pt(µ-OH)]22+.
Scheme 20: The mechanism of oxidation of ketones 67 in the presence of [(dppb}Pt(µ-OH)]22+ and H2O2.
Scheme 21: Oxidation of benzaldehydes 69 in the presence of the H2O2/MeReO3 system.
Scheme 22: Oxidation of acetophenones 72 in the presence of the H2O2/MeReO3 system.
Scheme 23: Baeyer–Villiger oxidation of 2-adamantanone (45c) in the presence of Sn-containing mesoporous silic...
Scheme 24: Aerobic Baeyer–Villiger oxidation of ketones 76 using metal-free carbon.
Scheme 25: A regioselective Baeyer-Villiger oxidation of functionalized cyclohexenones 78 into a dihydrooxepin...
Scheme 26: The oxidation of aldehydes and ketones 80 by H2O2 catalyzed by Co4HP2Mo15V3O62.
Scheme 27: The cleavage of ketones 82 with hydrogen peroxide in alkaline solution.
Scheme 28: Oxidation of ketones 85 to esters 86 with H2O2–urea in the presence of KHCO3.
Scheme 29: Mechanism of the asymmetric oxidation of cyclopentane-1,2-dione 87a with the Ti(OiPr)4/(+)DET/t-BuO...
Scheme 30: The oxidation of cis-4-tert-butyl-2-fluorocyclohexanone (93) with m-chloroperbenzoic acid.
Scheme 31: The mechanism of the asymmetric oxidation of 3-substituted cyclobutanone 96a in the presence of chi...
Scheme 32: Enantioselective Baeyer–Villiger oxidation of cyclic ketones 98.
Scheme 33: Regio- and enantioselective Baeyer–Villiger oxidation of cyclic ketones 101.
Scheme 34: The proposed mechanism of the Baeyer–Villiger oxidation of acetal 105f.
Scheme 35: Synthesis of hydroxy-10H-acridin-9-one 117 from tetramethoxyanthracene 114.
Scheme 36: The Baeyer–Villiger oxidation of the fully substituted pyrrole 120.
Scheme 37: The Criegee rearrangement.
Scheme 38: The mechanism of the Criegee reaction of a peracid with a tertiary alcohol 122.
Scheme 39: Criegee rearrangement of decaline ethylperoxoate 127 into ketal 128.
Scheme 40: The ionic cleavage of 2-methoxy-2-propyl perester 129.
Scheme 41: The Criegee rearrangement of α-methoxy hydroperoxide 136.
Scheme 42: Synthesis of enol esters and acetals via the Criegee rearrangement.
Scheme 43: Proposed mechanism of the transformation of 1-hydroperoxy-2-oxabicycloalkanones 147a–d.
Scheme 44: Transformation of 3-hydroxy-1,2-dioxolanes 151 into diketone derivatives 152.
Scheme 45: Criegee rearrangement of peroxide 153 with the mono-, di-, and tri-O-insertion.
Scheme 46: The sequential Criegee rearrangements of adamantanes 157a,b.
Scheme 47: Synthesis of diaryl carbonates 160a–d from triarylmethanols 159a–d through successive oxygen insert...
Scheme 48: The synthesis of sesquiterpenes 162 from ketone 161 with a Criegee rearrangement as one key step.
Scheme 49: Synthesis of trans-hydrindan derivatives 164, 165.
Scheme 50: The Hock rearrangement.
Scheme 51: The general scheme of the cumene process.
Scheme 52: The Hock rearrangement of aliphatic hydroperoxides.
Scheme 53: The mechanism of solvolysis of brosylates 174a–c and spiro cyclopropyl carbinols 175a–c in THF/H2O2....
Scheme 54: The fragmentation mechanism of hydroperoxy acetals 178 to esters 179.
Scheme 55: The acid-catalyzed rearrangement of phenylcyclopentyl hydroperoxide 181.
Scheme 56: The peroxidation of tertiary alcohols in the presence of a catalytic amount of acid.
Scheme 57: The acid-catalyzed reaction of bicyclic secondary alcohols 192 with hydrogen peroxide.
Scheme 58: The photooxidation of 5,6-disubstituted 3,4-dihydro-2H-pyrans 196.
Scheme 59: The oxidation of tertiary alcohols 200a–g, 203a,b, and 206.
Scheme 60: Transformation of functional peroxide 209 leading to 2,3-disubstitued furans 210 in one step.
Scheme 61: The synthesis of carbazoles 213 via peroxide rearrangement.
Scheme 62: The construction of C–N bonds using the Hock rearrangement.
Scheme 63: The synthesis of moiety 218 from 217 which is a structural motif in the antitumor–antibiotic of CC-...
Scheme 64: The in vivo oxidation steps of cholesterol (219) by singlet oxygen.
Scheme 65: The proposed mechanism of the rearrangement of cholesterol-5α-OOH 220.
Scheme 66: Photochemical route to artemisinin via Hock rearrangement of 223.
Scheme 67: The Kornblum–DeLaMare rearrangement.
Scheme 68: Kornblum–DeLaMare transformation of 1-phenylethyl tert-butyl peroxide (225).
Scheme 69: The synthesis 4-hydroxyenones 230 from peroxide 229.
Scheme 70: The Kornblum–DeLaMare rearrangement of peroxide 232.
Scheme 71: The reduction of peroxide 234.
Scheme 72: The Kornblum–DeLaMare rearrangement of endoperoxide 236.
Scheme 73: The rearrangement of peroxide 238 under Kornblum–DeLaMare conditions.
Scheme 74: The proposed mechanism of rearrangement of peroxide 238.
Scheme 75: The Kornblum–DeLaMare rearrangement of peroxides 242a,b.
Scheme 76: The base-catalyzed rearrangements of bicyclic endoperoxides having electron-withdrawing substituent...
Scheme 77: The base-catalyzed rearrangements of bicyclic endoperoxides 249a,b having electron-donating substit...
Scheme 78: The base-catalyzed rearrangements of bridge-head substituted bicyclic endoperoxides 251a,b.
Scheme 79: The Kornblum–DeLaMare rearrangement of hydroperoxide 253.
Scheme 80: Synthesis of β-hydroxy hydroperoxide 254 from endoperoxide 253.
Scheme 81: The amine-catalyzed rearrangement of bicyclic endoperoxide 263.
Scheme 82: The base-catalyzed rearrangement of meso-endoperoxide 268 into 269.
Scheme 83: The photooxidation of 271 and subsequent Kornblum–DeLaMare reaction.
Scheme 84: The Kornblum–DeLaMare rearrangement as one step in the oxidation reaction of enamines.
Scheme 85: The Kornblum–DeLaMare rearrangement of 3,5-dihydro-1,2-dioxenes 284, 1,2-dioxanes 286, and tert-but...
Scheme 86: The Kornblum–DeLaMare rearrangement of epoxy dioxanes 290a–d.
Scheme 87: Rearrangement of prostaglandin H2 292.
Scheme 88: The synthesis of epicoccin G (297).
Scheme 89: The Kornblum–DeLaMare rearrangement used in the synthesis of phomactin A.
Scheme 90: The Kornblum–DeLaMare rearrangement in the synthesis of 3H-quinazolin-4-one 303.
Scheme 91: The Kornblum–DeLaMare rearrangement in the synthesis of dolabriferol (308).
Scheme 92: Sequential transformation of 3-substituted 2-pyridones 309 into 3-hydroxypyridine-2,6-diones 311 in...
Scheme 93: The Kornblum–DeLaMare rearrangement of peroxide 312 into hydroxy enone 313.
Scheme 94: The Kornblum–DeLaMare rearrangement in the synthesis of polyfunctionalized carbonyl compounds 317.
Scheme 95: The Kornblum–DeLaMare rearrangement in the synthesis of (Z)-β-perfluoroalkylenaminones 320.
Scheme 96: The Kornblum–DeLaMare rearrangement in the synthesis of γ-ketoester 322.
Scheme 97: The Kornblum–DeLaMare rearrangement in the synthesis of diterpenoids 326 and 328.
Scheme 98: The synthesis of natural products hainanolidol (331) and harringtonolide (332) from peroxide 329.
Scheme 99: The synthesis of trans-fused butyrolactones 339 and 340.
Scheme 100: The synthesis of leucosceptroid C (343) and leucosceptroid P (344) via the Kornblum–DeLaMare rearra...
Scheme 101: The Dakin oxidation of arylaldehydes or acetophenones.
Scheme 102: The mechanism of the Dakin oxidation.
Scheme 103: A solvent-free Dakin reaction of aromatic aldehydes 356.
Scheme 104: The organocatalytic Dakin oxidation of electron-rich arylaldehydes 358.
Scheme 105: The Dakin oxidation of electron-rich arylaldehydes 361.
Scheme 106: The Dakin oxidation of arylaldehydes 358 in water extract of banana (WEB).
Scheme 107: A one-pot approach towards indolo[2,1-b]quinazolines 364 from indole-3-carbaldehydes 363 through th...
Scheme 108: The synthesis of phenols 367a–c from benzaldehydes 366a-c via acid-catalyzed Dakin oxidation.
Scheme 109: Possible transformation paths of the highly polarized boric acid coordinated H2O2–aldehyde adduct 3...
Scheme 110: The Elbs oxidation of phenols 375 to hydroquinones.
Scheme 111: The mechanism of the Elbs persulfate oxidation of phenols 375 affording p-hydroquinones 376.
Scheme 112: Oxidation of 2-pyridones 380 under Elbs persulfate oxidation conditions.
Scheme 113: Synthesis of 3-hydroxy-4-pyridone (384) via an Elbs oxidation of 4-pyridone (382).
Scheme 114: The Schenck rearrangement.
Scheme 115: The Smith rearrangement.
Scheme 116: Three main pathways of the Schenck rearrangement.
Scheme 117: The isomerization of hydroperoxides 388 and 389.
Scheme 118: Trapping of dioxacyclopentyl radical 392 by oxygen.
Scheme 119: The hypothetical mechanism of the Schenck rearrangement of peroxide 394.
Scheme 120: The autoxidation of oleic acid (397) with the use of labeled isotope 18O2.
Scheme 121: The rearrangement of 18O-labeled hydroperoxide 400 under an atmosphere of 16O2.
Scheme 122: The rearrangement of the oleate-derived allylic hydroperoxides (S)-421 and (R)-425.
Scheme 123: Mechanisms of Schenck and Smith rearrangements.
Scheme 124: The rearrangement and cyclization of 433.
Scheme 125: The Wieland rearrangement.
Scheme 126: The rearrangement of bis(triphenylsilyl) 439 or bis(triphenylgermyl) 441 peroxides.
Scheme 127: The oxidative transformation of cyclic ketones.
Scheme 128: The hydroxylation of cyclohexene (447) in the presence of tungstic acid.
Scheme 129: The oxidation of cyclohexene (447) under the action of hydrogen peroxide.
Scheme 130: The reaction of butenylacetylacetone 455 with hydrogen peroxide.
Scheme 131: The oxidation of bridged 1,2,4,5-tetraoxanes.
Scheme 132: The proposed mechanism for the oxidation of bridged 1,2,4,5-tetraoxanes.
Scheme 133: The rearrangement of ozonides.
Scheme 134: The acid-catalyzed oxidative rearrangement of malondialdehydes 462 under the action of H2O2.
Scheme 135: Pathways of the Lewis acid-catalyzed cleavage of dialkyl peroxides 465 and ozonides 466.
Scheme 136: The mechanism of the transformation of (tert-butyldioxy)cyclohexanedienones 472.
Scheme 137: The synthesis of Vitamin K3 from 472a.
Scheme 138: Proposed mechanism for the transformation of 478d into silylated endoperoxide 479d.
Scheme 139: The rearrangement of hydroperoxide 485 to form diketone 486.
Scheme 140: The base-catalyzed rearrangement of cyclic peroxides 488a–g.
Scheme 141: Synthesis of chiral epoxides and aldols from peroxy hemiketals 491.
Scheme 142: The multistep transformation of (R)-carvone (494) to endoperoxides 496a–e.
Scheme 143: The decomposition of anthracene endoperoxide 499.
Scheme 144: Synthesis of esters 503 from aldehydes 501 via rearrangement of peroxides 502.
Scheme 145: Two possible paths for the base-promoted decomposition of α-azidoperoxides 502.
Scheme 146: The Story decomposition of cyclic diperoxide 506a.
Scheme 147: The Story decomposition of cyclic triperoxide 506b.
Scheme 148: The thermal rearrangement of endoperoxides A into diepoxides B.
Scheme 149: The transformation of peroxide 510 in the synthesis of stemolide (511).
Scheme 150: The possible mechanism of the rearrangement of endoperoxide 261g.
Scheme 151: The photooxidation of indene 517.
Scheme 152: The isomerization of ascaridole (523).
Scheme 153: The isomerization of peroxide 525.
Scheme 154: The thermal transformation of endoperoxide 355.
Scheme 155: The photooxidation of cyclopentadiene (529) at a temperature higher than 0 °C.
Scheme 156: The thermal rearrangement of endoperoxides 538a,b.
Scheme 157: The transformation of peroxides 541.
Scheme 158: The thermal rearrangements of strained cyclic peroxides.
Scheme 159: The thermal rearrangement of diacyl peroxide 551 in the synthesis of C4-epi-lomaiviticin B core 553....
Scheme 160: The 1O2 oxidation of tryptophan (554) and rearrangement of dioxetane intermediate 555.
Scheme 161: The Fe(II)-promoted cleavage of aryl-substituted bicyclic peroxides.
Scheme 162: The proposed mechanism of the Fe(II)-promoted rearrangement of 557a–c.
Scheme 163: The reaction of dioxolane 563 with Fe(II) sulfate.
Scheme 164: Fe(II)-promoted rearrangement of 1,2-dioxane 565.
Scheme 165: Fe(II) cysteinate-promoted rearrangement of 1,2-dioxolane 568.
Scheme 166: The transformation of 1,2-dioxanes 572a–c under the action of FeCl2.
Scheme 167: Fe(II) cysteinate-promoted transformation of tetraoxane 574.
Scheme 168: The CoTPP-catalyzed transformation of bicyclic endoperoxides 600a–d.
Scheme 169: The CoTPP-catalyzed transformation of epoxy-1,2-dioxanes.
Scheme 170: The Ru(II)-catalyzed reactions of 1,4-endoperoxide 261g.
Scheme 171: The Ru(II)-catalyzed transformation as a key step in the synthesis of elyiapyrone A (610) from 1,4-...
Scheme 172: Peroxides with antimalarial activity.
Scheme 173: The interaction of iron ions with artemisinin (616).
Scheme 174: The interaction of FeCl2 with 1,2-dioxanes 623, 624.
Scheme 175: The mechanism of reaction 623 and 624 with Fe(II)Cl2.
Scheme 176: The reaction of bicyclic natural endoperoxides G3-factors 631–633 with FeSO4.
Scheme 177: The transformation of terpene cardamom peroxide 639.
Scheme 178: The different ways of the cleavage of tetraoxane 643.
Scheme 179: The LC–MS analysis of interaction of tetraoxane 646 with iron(II)heme 647.
Scheme 180: The rearrangement of 3,6-epidioxy-1,10-bisaboladiene (EDBD, 649).
Scheme 181: Easily oxidized substrates.
Scheme 182: Biopathway of synthesis of prostaglandins.
Scheme 183: The reduction and rearrangements of isoprostanes.
Scheme 184: The partial mechanism for linoleate 658 oxidation.
Scheme 185: The transformation of lipid hydroperoxide.
Scheme 186: The acid-catalyzed cleavage of the product from free-radical oxidation of cholesterol (667).
Scheme 187: Two pathways of catechols oxidation.
Scheme 188: Criegee-like or Hock-like rearrangement of the intermediate hydroperoxide 675 in dioxygenase enzyme...
Scheme 189: Carotinoides 679 cleavage by carotenoid cleavage dioxygenases.
Enantioselective carbenoid insertion into C(sp3)–H bonds
- J. V. Santiago and
- A. H. L. Machado
Beilstein J. Org. Chem. 2016, 12, 882–902, doi:10.3762/bjoc.12.87
- activation; chiral catalysis; diazo compounds; total synthesis; Introduction One of the major challenges met in organic synthesis is the formation of carbon–carbon bonds, in particular in a stereoselective way. Nucleophilic substitution reactions, radical reactions, cross-coupling reactions and the Heck
Graphical Abstract
Figure 1: Singlet carbene, triplet carbene and carbenoids.
Figure 2: Classification of the carbenoid intermediates by the electronic nature of the groups attached to th...
Figure 3: Chiral bis(oxazoline) ligands used in enantioselective copper carbenoid insertion.
Scheme 1: Pioneering work of Peter Yates on the carbenoid insertion reaction into X–H bonds (where X = O, S, ...
Scheme 2: Copper carbenoid insertion into C(sp3)–H bond of a stereogenic center with full retention of the as...
Scheme 3: Carbenoid insertion into a C(sp3)–H bond as the key step of the Taber’s (+)-α-cuparenone (8) synthe...
Scheme 4: First enantioselective carbenoid insertion into C–O bonds catalyzed by chiral metallic complexes.
Figure 4: Chemical structures of complexes (R)-18 and (S)-18.
Scheme 5: Asymmetric carbenoid insertions into C(sp3)–H bonds of cycloalkanes catalyzed by chiral rhodium car...
Scheme 6: First diastereo and enantioselective intermolecular carbenoid insertion into tetrahydrofuran C(sp3)...
Scheme 7: Simplified mechanism of the carbenoid insertion into a C(sp3)–H bond.
Scheme 8: Nakamura’s carbenoid insertion into a C(sp3)–H bond catalytic cycle.
Scheme 9: Investigation of the relationship between the electronic characteristics of the substituent X attac...
Scheme 10: Empirical model to predict the stereoselectivity of the donor/acceptor dirhodium carbenoid insertio...
Scheme 11: Asymmetric insertion of copper carbenoids in C(sp3)–H bonds to prepare trans-γ-lactam.
Figure 5: Iridium catalysts used by Suematsu and Katsuki for carbenoid insertion into C(sp3)–H bonds.
Scheme 12: Chiral porphyrin iridium complex catalyzes the carbenoid insertion into bis-allylic C(sp3)–H bonds.
Scheme 13: Chiral porphyrin iridium complex catalyzes the carbenoid insertion into tetrahydrofuran C(sp3)–H bo...
Scheme 14: Chiral porphyrin–iridium complex catalyzes the intramolecular carbenoid insertion into C(sp3)–H bon...
Scheme 15: Chiral bis(oxazoline)–iridium complex catalyzes the carbenoid insertion into bis-allylic C(sp3)–H b...
Scheme 16: New cyclopropylcarboxylate-based chiral catalyst to enantioselective carbenoid insertion into the e...
Scheme 17: Regio- and enantioselective carbenoid insertion into the C(sp3)–H bond catalyzed by a new bulky cyc...
Scheme 18: Regio and diastereoselective carbenoid insertion into the C(sp3)–H bond catalyzed by a new bulky cy...
Scheme 19: 2,2,2-Trichloroethyl (TCE) aryldiazoacetates to improve the scope, regio- and enantioselective of t...
Scheme 20: Sequential C–H functionalization approach to 2,3-dihydrobenzofurans.
Scheme 21: Enantioselective intramolecular rhodium carbenoid insertion into C(sp3)–H bonds to afford cis-disub...
Scheme 22: Enantioselective intramolecular rhodium carbenoid insertion into C(sp3)–H bonds to afford cis-2-vin...
Scheme 23: First rhodium porphyrin-based catalyst for enantioselective carbenoid insertion into C(sp3)–H bond.
Scheme 24: Rhodium porphyrin-based catalyst for enantioselective carbenoid insertion into benzylic C(sp3)–H bo...
Recent advances in C(sp3)–H bond functionalization via metal–carbene insertions
- Bo Wang,
- Di Qiu,
- Yan Zhang and
- Jianbo Wang
Beilstein J. Org. Chem. 2016, 12, 796–804, doi:10.3762/bjoc.12.78
- –carbene; site-selectivity; Introduction Direct functionalization of inactivated C–H bonds, especially C(sp3)–H bonds, have attracted significant attentions in recent years. The C(sp3)–H bond activation strategies based on radical reactions and transition metal catalysis have been explored, alongside the
Graphical Abstract
Scheme 1: Pathway for transition-metal-catalyzed carbene insertion into C(sp3)–H bonds.
Scheme 2: Rh(II)-catalyzed site-selective and enantioselective C–H functionalization of methyl ether.
Scheme 3: Late-stage C–H functionalization with Rh(II)-catalyzed carbene C(sp3)–H insertion.
Scheme 4: The Rh(II)-catalyzed selective carbene insertion into benzylic C–H bonds.
Scheme 5: The structure–selectivity relationship.
Scheme 6: Rh-porphyrin complexes for catalytic intermolecular C–H insertions.
Scheme 7: Asymmetric intermolecular C(sp3)–H insertion with chiral Rh-porphyrin catalyst.
Figure 1: The structure of TpM catalysts.
Scheme 8: Ag-Tpx-catalyzed intermolecular C–H insertion between EDA and alkanes.
Scheme 9: Ag-Tpx-catalyzed C–H insertion of methane with EDA in scCO2.
Figure 2: Structure of TpM-type catalysts.
Scheme 10: Comparison of site-selectivities of C–H insertion in different reaction media.
Scheme 11: C(sp3)–H bond insertion catalyzed by trinuclear cluster Ag.
Scheme 12: Zn(II)-catalyzed C(sp3)–H bond insertion.
Cascade alkylarylation of substituted N-allylbenzamides for the construction of dihydroisoquinolin-1(2H)-ones and isoquinoline-1,3(2H,4H)-diones
- Ping Qian,
- Bingnan Du,
- Wei Jiao,
- Haibo Mei,
- Jianlin Han and
- Yi Pan
Beilstein J. Org. Chem. 2016, 12, 301–308, doi:10.3762/bjoc.12.32
- -initiated cyclization [30][31] and other radical reactions [32][33][34]. Due to their low polarity and high bond-dissociation energy, the functionalization of unactivated sp3 C–H bonds in simple alkanes remains as a challenging task. The direct cascade, 1,2-alkyarylation of alkenes to construct multi
- -benzyl (4k), no obvious effect was found and almost the same level of yield was obtained as for 4a. However, a dramatically lower yield was obtained when a substrate with a N-phenyl group (4j) was used. We then carried out another substrate scope examination for the radical reactions using various
Graphical Abstract
Scheme 1: Cascade 1,2-difunctionalization and cyclization to construct heterocycles.
Scheme 2: Cyclization of cyclohexane (2a) with substituted N-(2-methylallyl)benzamide (reaction conditions: 4...
Scheme 3: Cyclization of cycloalkanes with N-methyl-N-(2-methylallyl)benzamide (reaction conditions: 4a (0.2 ...
Scheme 4: Cyclization reaction of 6 with cyclohexane 2a (reaction conditions: 6 (0.2 mmol), cyclohexane 2a (2...
Scheme 5: Control experiments for the mechanism studies. a) Reaction with N-unprotected substrate 8a; b) reac...
Scheme 6: Proposed mechanism.
Recent developments in copper-catalyzed radical alkylations of electron-rich π-systems
- Kirk W. Shimkin and
- Donald A. Watson
Beilstein J. Org. Chem. 2015, 11, 2278–2288, doi:10.3762/bjoc.11.248
- processes are generally thought to be related to long established atom-transfer radical reactions. However, unlike classical reactions, these new transformations lead to simple alkylation products. This short review will highlight recent advances in alkylations of nitronate anions, alkenes and alkynes, as
- non-catalyzed reactions. Mechanistically, it is believed that these reactions all share features of classic ATR reactions, but are distinct as they deliver simple alkylation products. These transformations represent a new paradigm in copper-catalyzed radical reactions. This article will highlight
Graphical Abstract
Scheme 1: Reactivity of nitronate anions towards alkyl electrophiles.
Scheme 2: Ligands tested in the alkylation of nitroalkanes with alkyl halides. aNaOt-Bu as base, hexanes as s...
Scheme 3: Scope of the copper-catalyzed nitroalkane benzylation.
Scheme 4: Application of the nitro-alkylation reaction to the synthesis of phentermine.
Scheme 5: Possible mechanism of the thermal redox process.
Scheme 6: Scope of the reaction of nitroalkanes with α-bromocarbonyls.
Scheme 7: Synthesis of highly congested β-amino acids.
Scheme 8: Copper-catalyzed alkenylation reactions.
Scheme 9: Proposed mechanism of the copper-catalyzed alkenylation reaction.
Scheme 10: Scope of the copper-catalyzed alkenylation of tertiary electrophiles.
Scheme 11: Scope of the exo-methylene styrene synthesis.
Scheme 12: Phenol-directed synthesis of Z-alkenes.
Scheme 13: Scope of the phenol-directed Z-alkene synthesis.
Scheme 14: Rationale for the formal [3 + 2] cycloaddition.
Scheme 15: Scope of the formal [3 + 2] cycloaddition.
Scheme 16: Benzylation of styrenes using copper catalysis.
Scheme 17: Copper-catalyzed carboiodination of alkynes.
Scheme 18: Copper-catalyzed trans-carbohalogenation of alkynes. aNaI (2 equiv) was added.
