Search for "isomerisation" in Full Text gives 82 result(s) in Beilstein Journal of Organic Chemistry.
Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101
Graphical Abstract
Figure 1: Bond lengths and bond angles in oxetane at 140 K [2].
Figure 2: Analogy of 3-substituted oxetanes to carbonyl and gem-dimethyl groups [12].
Figure 3: Use of oxetanes in drug design – selected examples.
Figure 4: Examples of oxetane-containing natural products.
Scheme 1: Synthetic strategies towards construction of the oxetane ring.
Scheme 2: Overview of intramolecular Williamson etherification and competing Grob fragmentation.
Scheme 3: Synthesis of spiro-oxetanes via 1,4-C–H insertion and Williamson etherification.
Scheme 4: Use of phenyl vinyl selenone in the synthesis of spirooxindole oxetanes.
Scheme 5: Synthesis of bicyclic 3,5-anhydrofuranoses via double epoxide opening/etherification.
Scheme 6: Preparation of spirooxetanes by cycloisomerisation via MHAT/RPC.
Scheme 7: Oxetane synthesis via alcohol C–H functionalisation.
Scheme 8: Access to oxetanes 38 from α-acetyloxy iodides.
Scheme 9: The kilogram-scale synthesis of oxetane intermediate 41.
Scheme 10: Overview of the intramolecular opening of 3-membered rings.
Scheme 11: Synthesis of 4,7-dioxatricyclo[3.2.1.03,6]octane skeletons.
Scheme 12: Silicon-directed electrophilic cyclisation of homoallylic alcohols.
Scheme 13: Hydrosilylation–iodocyclisation of homopropargylic alcohols.
Scheme 14: Cu-catalysed intramolecular O-vinylation of γ-bromohomoallylic alcohols.
Scheme 15: Cu-catalysed intramolecular cross-coupling of hydroxyvinylstannanes.
Scheme 16: Isomerisation of oxiranyl ethers containing weakly carbanion-stabilising groups.
Scheme 17: Cyclisation of diethyl haloalkoxymalonates.
Scheme 18: Synthesis of oxetanes through a 1,5-HAT/radical recombination sequence.
Scheme 19: General approach to oxetanes via [2 + 2] cycloadditions.
Scheme 20: Synthesis of tricyclic 4:4:4 oxetanes through a photochemical triple cascade reaction.
Scheme 21: Iridium-catalysed Paternò–Büchi reaction between α-ketoesters and simple alkenes.
Scheme 22: Three-step synthesis of spirocyclic oxetanes 83 via Paternò–Büchi reaction, nucleophilic ring openi...
Scheme 23: Enantioselective Paternò–Büchi reaction catalysed by a chiral iridium photocatalyst.
Scheme 24: Synthesis of polysubstituted oxetanes 92 via Cu(II)-mediated formal [2 + 2] cycloadditions.
Scheme 25: Synthesis of alkylideneoxetanes via NHC- and DBU-mediated formal [2 + 2] cycloadditions.
Scheme 26: Use of sulphur-stabilised carbanions in ring expansions.
Scheme 27: Synthesis of α,α-difluoro(arylthio)methyl oxetanes.
Scheme 28: Ring expansion in an industrial synthesis of PF-06878031.
Scheme 29: Ring contraction of triflated 2-hydroxy-γ-lactones.
Scheme 30: Ring contraction in an industrial synthesis of PF-06878031.
Scheme 31: Photochemical ring contraction of 2,5-dihydrofurans by aryldiazoacetic acid esters.
Scheme 32: Synthesis of 3-oxetanones via O-H insertion of carbenes.
Scheme 33: Synthesis of phosphonate oxetanones via gold-mediated alkyne oxidation/O–H insertion.
Scheme 34: Syntheses and common derivatisations of 3-oxetanone.
Scheme 35: SN1 substitution of 3-aryloxetan-3-ols by thiols and alcohols.
Scheme 36: Fe–Ni dual-catalytic olefin hydroarylation towards 3-alkyl-3-(hetero)aryloxetanes.
Scheme 37: Synthesis of 3-aryloxetan-3-carboxylic acids.
Scheme 38: Decarboxylative alkylation of 3-aryloxetan-3-carboxylic acids.
Scheme 39: Synthesis of 3-amino-3-aryloxetanes via photoredox/nickel cross-coupling catalysis.
Scheme 40: Intermolecular cross-selective [2 + 2] photocycloaddition towards spirooxetanes.
Scheme 41: Synthesis of 3-aryl-3-aminooxetanes via defluorosulphonylative coupling.
Scheme 42: Two-step synthesis of amide bioisosteres via benzotriazolyl Mannich adducts 170.
Scheme 43: Functionalisation of oxetanyl trichloroacetimidates 172.
Scheme 44: Synthesis of oxetane-amino esters 176.
Scheme 45: Tandem Friedel–Crafts alkylation/intramolecular ring opening of 3-aryloxetan-3-ols.
Scheme 46: Synthesis of polysubstituted furans and pyrroles.
Scheme 47: Synthesis of oxazolines and bisoxazolines.
Scheme 48: Tandem, one-pot syntheses of various polycyclic heterocycles.
Scheme 49: Synthesis of 1,2-dihydroquinolines via skeletal reorganisation of oxetanes.
Scheme 50: Synthesis of benzoindolines and 2,3-dihydrobenzofurans and their derivatisations.
Scheme 51: Synthesis of polysubstituted 1,4-dioxanes.
Scheme 52: Preparation of various lactones via ring opening of oxetane-carboxylic acids 219.
Scheme 53: Tsuji-Trost allylation/ring opening of 3-aminooxetanes.
Scheme 54: Arylative skeletal rearrangement of 3-vinyloxetan-3-ols to 2,5-dihydrofurans.
Scheme 55: Reductive opening of oxetanes using catalytic Mg–H species.
Scheme 56: Opening of oxetanes by silyl ketene acetals.
Scheme 57: Rhodium-catalysed hydroacylation of oxetanes.
Scheme 58: Generation of radicals from oxetanes mediated by a vitamin B12-derived cobalt catalyst.
Scheme 59: Reductive opening of oxetanes by B–Si frustrated Lewis pairs.
Scheme 60: Zirconocene-mediated reductive opening of oxetanes.
Scheme 61: Enantioselective syntheses of small and medium-size rings using chiral phosphoric acids.
Scheme 62: Asymmetric synthesis of 2,3-dihydrobenzo[b]oxepines catalysed by a chiral scandium complex.
Scheme 63: Enantioselective synthesis of 1,3-bromohydrins under a chiral squaramide catalysis.
Scheme 64: Enantioselective opening of 2-aryl-2-ethynyloxetanes by anilines.
Scheme 65: Ru-catalysed insertion of diazocarbonyls into oxetanes.
Scheme 66: Ring expansion of oxetanes by stabilised carbenes generated under blue light irradiation.
Scheme 67: Expansion of oxetanes via nickel-catalysed insertion of alkynyltrifluoroborates.
Scheme 68: Nickel-catalysed expansion of oxetanes into ε-caprolactones.
Scheme 69: Expansion of oxetanes via cobalt-catalysed carbonyl insertion.
Scheme 70: Gold-catalysed intramolecular 1,1-carboalkoxylation of oxetane-ynamides.
Scheme 71: Expansion of oxetanes by stabilised sulphoxonium ylides.
Scheme 72: Cu-catalysed ring expansion of 2-vinyloxetanes by diazoesters.
Scheme 73: Total synthesis of (+)-oxetin.
Scheme 74: Total synthesis of racemic oxetanocin A.
Scheme 75: Total synthesis of (−)-merrilactone A.
Scheme 76: Total synthesis of (+)-dictyoxetane.
Scheme 77: Total synthesis of ent-dichrocephone B.
Scheme 78: Total synthesis of (−)-mitrephorone A.
Scheme 79: Total synthesis of (−)-taxol.
Beilstein J. Org. Chem. 2025, 21, 680–716, doi:10.3762/bjoc.21.54
Graphical Abstract
Figure 1: Fundamental characteristics of the C–F bond.
Figure 2: Incorporation of fluorine at the end of an alkyl chain.
Figure 3: Incorporation of fluorine into the middle of a linear alkyl chain.
Figure 4: Incorporation of fluorine across much, or all, of a linear alkyl chain.
Figure 5: Incorporation of fluorine into cycloalkanes.
Figure 6: Conformational effects of introducing fluorine into an ether (geminal to oxygen).
Figure 7: Conformational effects of introducing fluorine into an ether (vicinal to oxygen).
Figure 8: Effects of introducing fluorine into alcohols (and their derivatives).
Figure 9: Controlling the ring pucker of sugars through fluorination.
Figure 10: Controlling bond rotations outside the sugar ring through fluorination.
Figure 11: Effects of incorporating fluorine into amines.
Figure 12: Effects of incorporating fluorine into amine derivatives, such as amides and sulfonamides.
Figure 13: Effects of incorporating fluorine into organocatalysts.
Figure 14: Effects of incorporating fluorine into carbonyl compounds, focusing on the “carbon side.”
Figure 15: Fluoroproline-containing peptides and proteins.
Figure 16: Further examples of fluorinated linear peptides (besides fluoroprolines). For clarity, sidechains a...
Figure 17: Fluorinated cyclic peptides.
Figure 18: Fluorine-derived conformational control in sulfur-containing compounds.
Beilstein J. Org. Chem. 2024, 20, 2931–2939, doi:10.3762/bjoc.20.245
Graphical Abstract
Figure 1: Structure and stability of hypervalent iodine compounds.
Figure 2: Phosphorus-iodonium ylids investigated in this study: Yields (for synthetic procedures, see Supporting Information File 1), stru...
Figure 3: (a) Selected TGA thermograms of phosphorus-iodonium ylids at 10 °C min−1 in N2 (full dataset in Supporting Information File 1). ...
Figure 4: (a) Proposed decomposition mechanism based on ex situ analysis (1H, 31P NMR, ESI-MS) following abor...
Beilstein J. Org. Chem. 2024, 20, 2668–2681, doi:10.3762/bjoc.20.224
Graphical Abstract
Scheme 1: Reaction between propylene oxide (PO) and CO2 and the five catalyst scaffolds under study. The posi...
Figure 1: Schematic representation of an (A) 2D and a (B) 3D volcano plot. The abbreviation “cat.” stands for...
Scheme 2: Capture reactions of CO2 or an epoxide by FLP.
Figure 2: (A) Structure of PO annotated with the C–O bond distances and electron densities at the BCPs. BCPs ...
Figure 3: Symmetric FLP scaffolds considered in the first study. X denotes N or P.
Figure 4: Subset of FLP scaffolds considered in the catalyst optimisation study. Substituents and labels are ...
Figure 5: Coupling reaction between PO and CO2. Depending on the catalyst considered, the reaction follows me...
Figure 6: VOLCANO plot group 1. The free energies of pre-TS01 assembly and Min2 are considered for the correl...
Figure 7: VOLCANO plot group 2. The free energies of pre-TS01 assembly and Min2 are considered for the correl...
Scheme 3: Asymmetric catalysis studied. On the left, the catalyst proposed by Gao et al. for the asymmetric h...
Figure 8: Catalysed reaction between the (S)-enantiomer of propylene oxide and CO2 resulting in the formation...
Figure 9: Schemes of the different asymmetric reactions observed. Hydrogen capable of rotation is marked in o...
Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201
Graphical Abstract
Scheme 1: The position of homoallylic amines in the landscape of alkaloid and nitrogen compounds syntheses.
Scheme 2: 3,3’-Diaryl-BINOL-catalysed asymmetric organocatalytic allylation of acylimines [24].
Scheme 3: Aminophenol-catalysed reaction between N-phosphinoylimines and pinacol allylboronic ester. Imine sc...
Scheme 4: Asymmetric geranylation and prenylation of indoles catalysed by (R)- or (S)-3,3’-dibromo-BINOL [25]. aA...
Scheme 5: (R)-3,3’-Di(3,5-di(trifluoromethyl)phenyl-BINOL-catalysed asymmetric geranylation and prenylation o...
Scheme 6: Microwave-induced one-pot asymmetric allylation of in situ-formed arylimines, catalysed by (R)-3,3’...
Scheme 7: Microwave-induced one-pot asymmetric allylation of in situ-formed arylimines, catalysed by (R)-3,3’...
Scheme 8: Kinetic resolution of chiral secondary allylboronates [15,30].
Scheme 9: (E)-Stereospecific asymmetric α-trifluoromethylallylation of cyclic imines and hydrazones [31].
Scheme 10: Hosomi–Sakurai-type allylation of in situ-formed N-Fmoc aldimines [32].
Figure 1: Two different pathways for the Hosomi–Sakurai reaction of allyltrimethylsilane with N-Fmoc aldimine...
Scheme 11: Chiral squaramide-catalysed hydrogen bond-assisted chloride abstraction–allylation of N-carbamoyl α...
Figure 2: The pyrrolidine unit gem-methyl group conformational control in the squaramide-based catalyst [34].
Figure 3: The energetic difference between the transition states of the two proposed modes of the reaction (SN...
Scheme 12: One-pot preparation procedure for oxazaborolidinium ion (COBI) 63 [37].
Scheme 13: Chiral oxazaborolidinium ion (COBI)-catalysed allylation of N-(2-hydroxy)phenylimines with allyltri...
Scheme 14: The two-step N-(2-hydroxy)phenyl group deprotection procedure [37].
Scheme 15: Low-temperature (−40 °C) NMR experiments evidencing the reversible formation of the active COBI–imi...
Figure 4: Two computed reaction pathways for the COBI-catalysed Strecker reaction (TS1 identical to allylatio...
Scheme 16: Highly chemoselective and stereospecific synthesis of γ- and γ,δ-substituted homoallylic amines by ...
Scheme 17: Catalytic cycle for the three-component allylation with HBD/πAr–Ar catalyst [39].
Scheme 18: Reactivity of model electrophiles [39].
Scheme 19: HBD/πAr–Ar catalyst rational design and optimisation [39].
Scheme 20: Scope of the three-component HBD/πAr–Ar-catalysed reaction [39].
Scheme 21: Limitations of the HBD/πAr–Ar-catalysed reaction [39].
Scheme 22: Asymmetric chloride-directed dearomative allylation of in situ-generated N-acylquinolinium ions, ca...
Scheme 23: Chiral phosphoric acid-catalysed aza-Cope rearrangement of in situ-formed N-α,α’-diphenyl-(α’’-ally...
Scheme 24: Tandem (R)-VANOL-triborate-catalysed asymmetric aza-Cope rearrangement of in situ-formed aldimines ...
Scheme 25: (S)-TRIP-catalysed enantioconvergent aza-Cope rearrangement of β-formyl amides, substrate scope [43]. a...
Scheme 26: (S)-TRIP-catalysed enantioconvergent aza-Cope rearrangement of β-formyl amides 16–19, amide and all...
Scheme 27: Synthetic applications of homoallylic N-benzophenone imine products 131 [43].
Scheme 28: Chiral organocatalysed addition of 2,2,2-trifluoroethyl ketimines to isatin-derived Morita–Baylis–H...
Scheme 29: Chiral chinchona-derived amine-catalysed reaction between isatin-based Morita–Baylis–Hilman carbona...
Scheme 30: (R)-VAPOL-catalysed hydrogen atom transfer deracemisation [45].
Scheme 31: Chiral PA-catalysed [1,3]-rearrangement of ene-aldimines [46].
Beilstein J. Org. Chem. 2024, 20, 2005–2015, doi:10.3762/bjoc.20.176
Graphical Abstract
Figure 1: E–Z isomerisation of (a) AzoTAB and (b) AAPTAB under UV light (365 nm) results in a change in shape...
Figure 2: SAXS curves for AzoTAB (50 mM in water) showing the transition from the Z-rich PSS to the E-rich st...
Figure 3: SAXS curves for the Z-rich PSS of AAPTAB (50 mM) in (a) water (H2O) and (b) deuterium dioxide (D2O)...
Figure 4: Addition of excess acid (pH = 0.4) induces Z–E isomerisation in AzoTAB and AAPTAB. UV–vis absorbanc...
Figure 5: Effect of X-ray exposure time on high-concentration samples of AAPTAB in water, (a) 10 wt % and (b)...
Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78
Graphical Abstract
Figure 1: Scaffolds commonly reported as bioisosteric replacements of para-substituted benzene and examples p...
Figure 2: 1,2-BCPs as isosteres for ortho-and meta-substituted benzenes: comparison of reported exit vector p...
Scheme 1: 1,2-Disubstituted bicyclo[1.1.1]pentanes as isosteres of ortho-substituted benzenes. A: Baran, Coll...
Scheme 2: Synthesis of 1,2-BCPs from BCP 15 by bridge C–H bromination as reported by MacMillan and co-workers ...
Figure 3: Comparative physicochemical data of telmisartan, lomitapide and their BCP isosteres [26,33]. Shake flask d...
Figure 4: 1,2-Disubstituted bicyclo[2.1.1]hexanes as isosteres of ortho-benzenes: Exit vector parameters of t...
Scheme 3: Synthesis of 1,2-disubstituted bicyclo[2.1.1]hexanes via alkene insertion into bicyclo[1.1.0]butane...
Scheme 4: Synthesis of 1,2-disubstituted bicyclo[2.1.1]hexanes via intramolecular crossed [2 + 2] cycloadditi...
Figure 5: Comparison of physicochemical data of fluxapyroxad and boscalid and their 1,2-BCH bioisosteres [36]. Sh...
Figure 6: Antifungal activity of fluxapyroxad, its 1,5-BCH bioisostere (±)-55, boscalid and its bioisostere 1...
Figure 7: 1,5-Disubstituted bicyclo[2.1.1]hexanes as isosteres of ortho-substituted benzenes. Comparison of e...
Scheme 5: Synthesis of 1,5-disubstituted bicyclo[2.1.1]hexanes as isosteres of ortho-benzenes via intramolecu...
Figure 8: Comparison of physicochemical data of fluxapyroxad and boscalid and their 1,5-BCH bioisosteres [45]. Sh...
Figure 9: Antifungal activity of fluxapyroxad, its 1,5-BCH bioisostere (±)-64, boscalid and its bioisostere 1...
Figure 10: 1,5-Disubstituted 3-oxabicylco[2.1.1]hexanes as isosteres for ortho-benzenes: Comparison of exit ve...
Scheme 6: Synthesis of 1,5-disubstituted 3-oxabicyclo[2.1.1]hexanes as isosteres for ortho-benzenes via intra...
Figure 11: Comparison of physicochemical data of fluxapyroxad and boscalid and their 3-oxa-1,5-BCH bioisostere...
Figure 12: Antifungal activity of fluxapyroxad and boscalid and their 3-oxa-1,5-BCH bioisosteres (±)-75 and (±...
Figure 13: 1,2-Disubstituted bicyclo[3.1.1]heptanes as isosteres of ortho-benzenes. Schematic representation o...
Scheme 7: Synthesis of 1,2-disubstituted bicyclo[3.1.1]heptanes as isosteres for ortho-benzenes via alkene in...
Figure 14: 1,2-Disubstituted stellanes as ortho-benzene isosteres: Comparison of selected exit vector paramete...
Scheme 8: Synthesis of 1,2-disubstituted stellanes as isosteres for ortho-benzenes reported by Ryabukhin, Vol...
Figure 15: 1,2-Disubstituted cubanes as ortho-benzene isosteres: Comparison of substituent distances and angle...
Scheme 9: Synthesis of 1,2-disubsituted cubanes as isosteres for ortho-benzenes. A: Synthesis of 1,2-cubane d...
Figure 16: 1,3-Disubstituted bicyclo[2.1.1]hexanes as isosteres of meta-benzenes: comparative exit vector para...
Scheme 10: Synthesis of 1,3-disubstituted bicyclo[2.1.1]hexanes as isosteres for meta-benzenes reported by Wal...
Figure 17: 1,4-Disubstituted bicyclo[2.1.1]hexanes as isosteres of meta-benzenes: comparative exit vector para...
Scheme 11: Synthesis of 1,4-disubstituted bicyclo[2.1.1}hexanes as isosteres for ortho-benzenes via intramolec...
Figure 18: 1,4-Disubstituted-2-oxabicyclo[2.1.1]hexanes as meta-benzene isosteres: comparison of selected exit...
Scheme 12: Synthesis of 1,4-disubstituted 2-oxabicyclo[2.1.1]hexanes as isosteres for meta-benzenes. A: Mykhai...
Figure 19: Comparative physicochemical data for 2- and 3-oxa-1,4-BCHs and para-substituted benzene equivalents...
Figure 20: 1,5-Disubstituted bicyclo[3.1.1]heptanes as isosteres of meta-benzenes: comparison of exit vector p...
Scheme 13: Synthesis of [3.1.1]propellane as a precursor for 1,5-disubsituted bicyclo[3.1.1]heptanes. A: aGass...
Scheme 14: Synthesis of iodine-substituted 1,5-disubstituted bicyclo[3.1.1]heptanes as isosteres for meta-benz...
Scheme 15: Synthesis of nitrogen-, chalcogen- and tin-substituted 1,5-disubstituted bicyclo[3.1.1]heptanes as ...
Figure 21: Comparative physicochemical data of URB597 and 1,5-BCHep isostere 146 [27]. Kinetic aqueous solubility ...
Figure 22: [2]-Ladderanes as isosteres of meta-benzenes: comparison of reported exit vector parameters [63].
Scheme 16: Synthesis of cis-2,6-disubstituted bicyclo[2.2.0]hexanes as isosteres for meta-benzenes. A: Brown a...
Figure 23: Comparative physicochemical data of meta-benzene 158 and [2]-ladderane isostere 159 [63]. Partition coe...
Figure 24: 1,3-Disubstituted cubanes as isosteres of meta-benzenes: comparison of selected exit vector paramet...
Scheme 17: Synthesis of 1,3-disubsituted cubanes as isosteres for meta-benzenes. A: MacMillan and co-workers’ ...
Figure 25: Comparative physicochemical data of lumacaftor and its 1,3-cubane bioisostere 183 [51]. Distribution co...
Figure 26: 1,3-Disubstituted cuneanes as isosteres of meta-benzenes: comparison of selected exit vector parame...
Scheme 18: Synthesis of 1,3-cuneanes as isosteres of meta-benzene. A: Synthesis of 1,3-cuneanes reported by La...
Figure 27: Comparative physicochemical data of sonidegib and its 1,3-cuneane isostere 190 [71]. aSolubility was to...
Figure 28: Exemplary polysubstituted scaffolds related to disubstituted scaffolds suggested as isosteres of or...
Beilstein J. Org. Chem. 2024, 20, 734–740, doi:10.3762/bjoc.20.67
Graphical Abstract
Scheme 1: Biosynthetic model for bacillaene (1). M1–M17 indicate modules 1–17. A = adenylation domain, ACP = ...
Scheme 2: Synthesis of the BaeJ-KS2 substrate surrogates (S)-11 and (R)-11. Green dots represent 13C-labelled...
Figure 1: 13C NMR spectra of (R)-11 incubated with BaeJ-KS2 and BaeJ-KS2-C222A. A) Free 11 dissolved in incub...
Beilstein J. Org. Chem. 2023, 19, 1452–1459, doi:10.3762/bjoc.19.104
Graphical Abstract
Scheme 1: The biosynthesis of 2-methylisoborneol (1). A) SAM-dependent methylation of GPP to 2-Me-GPP by GPPM...
Figure 1: The function of the N-terminal A domain of 2MIBS. A) Relative production of 1 with full length 2MIB...
Scheme 2: Enzymatic synthesis of analogs of 1. A) Preparation of 2 from DA-4 and IA-1, B) preparation of 3 an...
Beilstein J. Org. Chem. 2023, 19, 325–348, doi:10.3762/bjoc.19.28
Graphical Abstract
Scheme 1: Group 13 exchange.
Scheme 2: Borane-catalysed hydroboration of alkynes and the proposed mechanism.
Scheme 3: a) Borane-catalysed hydroboration of alkenes and the proposed mechanism. b) H-B-9-BBN-catalysed dou...
Scheme 4: a) Amine-borane-catalysed C‒H borylation of heterocycles and the proposed mechanism. b) Benzoic aci...
Scheme 5: Bis(pentafluorophenyl)borane-catalysed dimerisation of allenes and the proposed mechanism.
Scheme 6: Alkoxide-promoted hydroboration of heterocycles and the proposed mechanism.
Scheme 7: Borane-catalysed reduction of indoles and the proposed mechanism.
Scheme 8: H-B-9-BBN-catalysed hydrocyanation of enones and the proposed mechanism.
Scheme 9: Borane-catalysed hydroboration of nitriles and the proposed mechanism.
Scheme 10: Myrtanylborane-catalysed asymmetric reduction of propargylic ketones and the proposed mechanism.
Scheme 11: H-B-9-BBN-catalysed C–F esterification of alkyl fluorides and the proposed mechanism.
Scheme 12: H-B-9-BBN-catalysed 1,4-hydroboration of enones and the proposed mechanism.
Scheme 13: Boric acid-promoted reduction of esters, lactones, and carbonates and the proposed mechanism.
Scheme 14: H-B-9-BBN-catalysed reductive aldol-type reaction and the proposed mechanism.
Scheme 15: H-B-9-BBN-catalysed diastereoselective allylation of ketones and the Ph-BBD-catalysed enantioselect...
Scheme 16: H-B-9-BBN-catalysed C–F arylation of benzyl fluorides and the proposed mechanism.
Scheme 17: Borane-catalysed S‒H borylation of thiols and the proposed mechanism.
Scheme 18: Borane-catalysed hydroalumination of alkenes and allenes.
Scheme 19: a) Aluminium-catalysed hydroboration of alkynes and example catalysts. b) Deprotonation mechanistic...
Scheme 20: Aluminium-catalysed hydroboration of alkenes and the proposed mechanism.
Scheme 21: Aluminium-catalysed C–H borylation of terminal alkynes and the proposed mechanism.
Scheme 22: Aluminium-catalysed dehydrocoupling of amines, alcohols, and thiols with H-B-9-BBN or HBpin and the...
Scheme 23: Aluminium-catalysed hydroboration of unsaturated compounds and the general reaction mechanism.
Scheme 24: a) Gallium-catalysed asymmetric hydroboration of ketones and the proposed mechanism. b) Gallium-cat...
Scheme 25: Gallium(I)-catalysed allylation/propargylation of acetals and aminals and the proposed mechanism.
Scheme 26: Indium(I)-catalysed allylation/propargylation of acetals, aminals, and alkyl ethers.
Scheme 27: Iron–indium cocatalysed double hydroboration of nitriles and the proposed mechanism.
Figure 1: a) The number of reports for a given group 13 exchange in catalysis. b) Average free energy barrier...
Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18
Graphical Abstract
Scheme 1: Possible cyclisation modes of FPP.
Scheme 2: Structures of germacrene B (1), germacrene A (2) and hedycaryol (3).
Scheme 3: The chemistry of germacrene B (1). A) Synthesis from germacrone (4), B) the four conformers of 1 es...
Scheme 4: The chemistry of germacrene B (1). A) Cyclisation of 1 to 9 and 10 upon treatment with alumina, B) ...
Scheme 5: Possible cyclisation reactions upon reprotonation of 1. A) Cyclisations to eudesmane sesquiterpenes...
Scheme 6: Cyclisation modes for 1 to the eudesmane skeleton. A) The reprotonation of 1 at C-1 potentially lea...
Scheme 7: The sesquiterpenes derived from cation I1. WMR = Wagner–Meerwein rearrangement.
Scheme 8: The sesquiterpenes derived from cation I1. A) Pyrolysis of 23 to yield 9 and 10, B) deprotonation–r...
Scheme 9: The sesquiterpenes derived from cation I1. A) Acid-catalysed conversion of 18 into 26, B) conversio...
Scheme 10: The sesquiterpenes derived from cation I1. A) Formation of 20 by pyrolysis of 33, B) acid-catalysed...
Scheme 11: The sesquiterpenes derived from cation I2. WMR = Wagner–Meerwein rearrangement.
Scheme 12: The sesquiterpenes derived from cation I2. A) Acid catalysed conversion of 41 into 38, B) dehydrati...
Scheme 13: The sesquiterpenes derived from cation I3. WMR = Wagner–Meerwein rearrangement.
Scheme 14: Cyclisation modes for 1 to the guaiane skeleton. A) The reprotonation of 1 at C-4 potentially leads...
Scheme 15: The sesquiterpenes derived from cations K1, K2 and K4. A) Mechanisms of formation for compounds 53–...
Scheme 16: The sesquiterpenes derived from cations L1–L4. A) Mechanisms of formation for compounds 54, 56, 59 ...
Beilstein J. Org. Chem. 2022, 18, 1–12, doi:10.3762/bjoc.18.1
Graphical Abstract
Scheme 1: Synthesis of SMC stapled axin CBD peptides. Reaction conditions: (a) Pd2(dba)3, sSPhos, KF, DME/EtO...
Scheme 2: Overview of the different cross-linkages obtained by intramolecular SMC. A) General structure of SM...
Figure 1: Analysis of the secondary structure by circular dichroism: CD spectra of both isomers of stapled pe...
Figure 2: In vitro binding affinities to β-catenin determined by competitive fluorescence polarisation assays....
Figure 3: Cleavage sites of Proteinase K digestion indicated by a red arrow.
Figure 4: Principal component analysis (PCA) of the macrocycle’s non-hydrogen atoms in the two isomers of P5....
Figure 5: Molecular modelling of the conformational preferences of the SMC stapled peptides P5 (with cis or t...
Beilstein J. Org. Chem. 2021, 17, 1939–1951, doi:10.3762/bjoc.17.127
Graphical Abstract
Figure 1: Examples of indazole natural products (1 and 2) and synthetic biologically active indazole derivati...
Scheme 1: Synthetic approaches to N-1 substituted indazole derivatives [12-14].
Scheme 2: N-Alkylation of indazole 9 under Mitsunobu conditions shows a strong preference (ratio N-1 (10):N-2...
Figure 2: Observation of a 1H–13C correlation between the C-7a (blue circle) or C-3 (red circle) atom of the ...
Figure 3: C-3 substituted indazole derivatives (12–24) employed to investigate C-3 substituent effects on ind...
Scheme 3: Proposed mechanism for the regioselective N-1 alkylation of indazoles 9, 19, and 21–24 in the prese...
Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90
Graphical Abstract
Figure 1: Representative shares of the global F&F market (2018) segmented on their applications [1].
Figure 2: General structure of an international fragrance company [2].
Figure 3: The Michael Edwards fragrance wheel.
Figure 4: Examples of oriental (1–3), woody (4–7), fresh (8–10), and floral (11 and 12) notes.
Figure 5: A basic depiction of batch vs flow.
Scheme 1: Examples of reactions for which flow processing outperforms batch.
Scheme 2: Some industrially important aldol-based transformations.
Scheme 3: Biphasic continuous aldol reactions of acetone and various aldehydes.
Scheme 4: Aldol synthesis of 43 in flow using LiHMDS as the base.
Scheme 5: A semi-continuous synthesis of doravirine (49) involving a key aldol reaction.
Scheme 6: Enantioselective aldol reaction using 5-(pyrrolidin-2-yl)tetrazole (51) as catalyst in a microreact...
Scheme 7: Gröger's example of asymmetric aldol reaction in aqueous media.
Figure 6: Immobilised reagent column reactor types.
Scheme 8: Photoinduced thiol–ene coupling preparation of silica-supported 5-(pyrrolidin-2-yl)tetrazole 63 and...
Scheme 9: Continuous-flow approach for enantioselective aldol reactions using the supported catalyst 67.
Scheme 10: Ötvös’ employment of a solid-supported peptide aldol catalyst in flow.
Scheme 11: The use of proline tetrazole packed in a column for aldol reaction between cyclohexanone (65) and 2...
Scheme 12: Schematic diagram of an aminosilane-grafted Si-Zr-Ti/PAI-HF reactor for continuous-flow aldol and n...
Scheme 13: Continuous-flow condensation for the synthesis of the intermediate 76 to nabumetone (77) and Microi...
Scheme 14: Synthesis of ψ-Ionone (80) in continuous-flow via aldol condensation between citral (79) and aceton...
Scheme 15: Synthesis of β-methyl-ionones (83) from citral (79) in flow. The steps are separately described, an...
Scheme 16: Continuous-flow synthesis of 85 from 84 described by Gavriilidis et al.
Scheme 17: Continuous-flow scCO2 apparatus for the synthesis of 2-methylpentanal (87) and the self-condensed u...
Scheme 18: Chen’s two-step flow synthesis of coumarin (90).
Scheme 19: Pechmann condensation for the synthesis of 7-hydroxyxcoumarin (93) in flow. The setup extended to c...
Scheme 20: Synthesis of the dihydrojasmonate 35 exploiting nitro derivative proposed by Ballini et al.
Scheme 21: Silica-supported amines as heterogeneous catalyst for nitroaldol condensation in flow.
Scheme 22: Flow apparatus for the nitroaldol condensation of p-hydroxybenzaldehyde (102) to nitrostyrene 103 a...
Scheme 23: Nitroaldol reaction of 64 to 105 employing a quaternary ammonium functionalised PANF.
Scheme 24: Enantioselective nitroaldol condensation for the synthesis of 108 under flow conditions.
Scheme 25: Enatioselective synthesis of 1,2-aminoalcohol 110 via a copper-catalysed nitroaldol condensation.
Scheme 26: Examples of Knoevenagel condensations applied for fragrance components.
Scheme 27: Flow apparatus for Knoevenagel condensation described in 1989 by Venturello et al.
Scheme 28: Knoevenagel reaction using a coated multichannel membrane microreactor.
Scheme 29: Continuous-flow apparatus for Knoevenagel condensation employing sugar cane bagasse as support deve...
Scheme 30: Knoevenagel reaction for the synthesis of 131–135 in flow using an amine-functionalised silica gel. ...
Scheme 31: Continuous-flow synthesis of compound 137, a key intermediate for the synthesis of pregabalin (138)...
Scheme 32: Continuous solvent-free apparatus applied for the synthesis of compounds 140–143 using a TSE. Throu...
Scheme 33: Lewis et al. developed a spinning disc reactor for Darzens condensation of 144 and a ketone to furn...
Scheme 34: Some key industrial applications of conjugate additions in the F&F industry.
Scheme 35: Continuous-flow synthesis of 4-(2-hydroxyethyl)thiomorpholine 1,1-dioxide (156) via double conjugat...
Scheme 36: Continuous-flow system for Michael addition using CsF on alumina as the catalyst.
Scheme 37: Calcium chloride-catalysed asymmetric Michael addition using an immobilised chiral ligand.
Scheme 38: Continuous multistep synthesis for the preparation of (R)-rolipram (173). Si-NH2: primary amine-fun...
Scheme 39: Continuous-flow Michael addition using ion exchange resin Amberlyst® A26.
Scheme 40: Preparation of the heterogeneous catalyst 181 developed by Paixão et al. exploiting Ugi multicompon...
Scheme 41: Continuous-flow system developed by the Paixão’s group for the preparation of Michael asymmetric ad...
Scheme 42: Continuous-flow synthesis of nitroaldols catalysed by supported catalyst 184 developed by Wennemers...
Scheme 43: Heterogenous polystyrene-supported catalysts developed by Pericàs and co-workers.
Scheme 44: PANF-supported pyrrolidine catalyst for the conjugate addition of cyclohexanone (65) and trans-β-ni...
Scheme 45: Synthesis of (−)-paroxetine precursor 195 developed by Ötvös, Pericàs, and Kappe.
Scheme 46: Continuous-flow approach for the 5-step synthesis of (−)-oseltamivir (201) as devised by Hayashi an...
Scheme 47: Continuous-flow enzyme-catalysed Michael addition.
Scheme 48: Continuous-flow copper-catalysed 1,4 conjugate addition of Grignard reagents to enones. Reprinted w...
Scheme 49: A collection of commonly encountered hydrogenation reactions.
Figure 7: The ThalesNano H-Cube® continuous-flow hydrogenator.
Scheme 50: Chemoselective reduction of an α,β-unsaturated ketone using the H-Cube® reactor.
Scheme 51: Incorporation of Lindlar’s catalyst into the H-Cube® reactor for the reduction of an alkyne.
Scheme 52: Continuous-flow semi-hydrogenation of alkyne 208 to 209 using SACs with H-Cube® system.
Figure 8: The standard setups for tube-in-tube gas–liquid reactor units.
Scheme 53: Homogeneous hydrogenation of olefins using a tube-in-tube reactor setup.
Scheme 54: Recyclable heterogeneous flow hydrogenation system.
Scheme 55: Leadbeater’s reverse tube-in-tube hydrogenation system for olefin reductions.
Scheme 56: a) Hydrogenation using a Pd-immobilised microchannel reactor (MCR) and b) a representation of the i...
Scheme 57: Hydrogenation of alkyne 238 exploiting segmented flow in a Pd-immobilised capillary reactor.
Scheme 58: Continuous hydrogenation system for the preparation of cyrene (241) from (−)-levoglucosenone (240).
Scheme 59: Continuous hydrogenation system based on CSMs developed by Hornung et al.
Scheme 60: Chemoselective reduction of carbonyls (ketones over aldehydes) in flow.
Scheme 61: Continuous system for the semi-hydrogenation of 256 and 258, developed by Galarneau et al.
Scheme 62: Continuous synthesis of biodiesel fuel 261 from lignin-derived furfural acetone (260).
Scheme 63: Continuous synthesis of γ-valerolacetone (263) via CTH developed by Pineda et al.
Scheme 64: Continuous hydrogenation of lignin-derived biomass (products 265, 266, and 267) using a sustainable...
Scheme 65: Ru/C or Rh/C-catalysed hydrogenation of arene in flow as developed by Sajiki et al.
Scheme 66: Polysilane-immobilized Rh–Pt-catalysed hydrogenation of arenes in flow by Kobayashi et al.
Scheme 67: High-pressure in-line mixing of H2 for the asymmetric reduction of 278 at pilot scale with a 73 L p...
Figure 9: Picture of the PFR employed at Eli Lilly & Co. for the continuous hydrogenation of 278 [287]. Reprinted ...
Scheme 68: Continuous-flow asymmetric hydrogenation using Oppolzer's sultam 280 as chiral auxiliary.
Scheme 69: Some examples of industrially important oxidation reactions in the F&F industry. CFL: compact fluor...
Scheme 70: Gold-catalysed heterogeneous oxidation of alcohols in flow.
Scheme 71: Uozumi’s ARP-Pt flow oxidation protocol.
Scheme 72: High-throughput screening of aldehyde oxidation in flow using an in-line GC.
Scheme 73: Permanganate-mediated Nef oxidation of nitroalkanes in flow with the use of in-line sonication to p...
Scheme 74: Continuous-flow aerobic anti-Markovnikov Wacker oxidation.
Scheme 75: Continuous-flow oxidation of 2-benzylpyridine (312) using air as the oxidant.
Scheme 76: Continuous-flow photo-oxygenation of monoterpenes.
Scheme 77: A tubular reactor design for flow photo-oxygenation.
Scheme 78: Glucose oxidase (GOx)-mediated continuous oxidation of glucose using compressed air and the FFMR re...
Scheme 79: Schematic continuous-flow sodium hypochlorite/TEMPO oxidation of alcohols.
Scheme 80: Oxidation using immobilised TEMPO (344) was developed by McQuade et al.
Scheme 81: General protocol for the bleach/catalytic TBAB oxidation of aldehydes and alcohols.
Scheme 82: Continuous-flow PTC-assisted oxidation using hydrogen peroxide. The process was easily scaled up by...
Scheme 83: Continuous-flow epoxidation of cyclohexene (348) and in situ preparation of m-CPBA.
Scheme 84: Continuous-flow epoxidation using DMDO as oxidant.
Scheme 85: Mukayama aerobic epoxidation optimised in flow mode by the Favre-Réguillon group.
Scheme 86: Continuous-flow asymmetric epoxidation of derivatives of 359 exploiting a biomimetic iron catalyst.
Scheme 87: Continuous-flow enzymatic epoxidation of alkenes developed by Watts et al.
Scheme 88: Engineered multichannel microreactor for continuous-flow ozonolysis of 366.
Scheme 89: Continuous-flow synthesis of the vitamin D precursor 368 using multichannel microreactors. MFC: mas...
Scheme 90: Continuous ozonolysis setup used by Kappe et al. for the synthesis of various substrates employing ...
Scheme 91: Continuous-flow apparatus for ozonolysis as developed by Ley et al.
Scheme 92: Continuous-flow ozonolysis for synthesis of vanillin (2) using a film-shear flow reactor.
Scheme 93: Examples of preparative methods for ajoene (386) and allicin (388).
Scheme 94: Continuous-flow oxidation of thioanisole (389) using styrene-based polymer-supported peroxytungstat...
Scheme 95: Continuous oxidation of thiosulfinates using Oxone®-packed reactor.
Scheme 96: Continuous-flow electrochemical oxidation of thioethers.
Scheme 97: Continuous-flow oxidation of 400 to cinnamophenone (235).
Scheme 98: Continuous-flow synthesis of dehydrated material 401 via oxidation of methyl dihydrojasmonate (33).
Scheme 99: Some industrially important transformations involving Grignard reagents.
Scheme 100: Grachev et al. apparatus for continuous preparation of Grignard reagents.
Scheme 101: Example of fluidized Mg bed reactor with NMR spectrometer as on-line monitoring system.
Scheme 102: Continuous-flow synthesis of Grignard reagents and subsequent quenching reaction.
Figure 10: Membrane-based, liquid–liquid separator with integrated pressure control [52]. Adapted with permission ...
Scheme 103: Continuous-flow synthesis of 458, an intermediate to fluconazole (459).
Scheme 104: Continuous-flow synthesis of ketones starting from benzoyl chlorides.
Scheme 105: A Grignard alkylation combining CSTR and PFR technologies with in-line infrared reaction monitoring....
Scheme 106: Continuous-flow preparation of 469 from Grignard addition of methylmagnesium bromide.
Scheme 107: Continuous-flow synthesis of Grignard reagents 471.
Scheme 108: Preparation of the Grignard reagent 471 using CSTR and the continuous process for synthesis of the ...
Scheme 109: Continuous process for carboxylation of Grignard reagents in flow using tube-in-tube technology.
Scheme 110: Continuous synthesis of propargylic alcohols via ethynyl-Grignard reagent.
Scheme 111: Silica-supported catalysed enantioselective arylation of aldehydes using Grignard reagents in flow ...
Scheme 112: Acid-catalysed rearrangement of citral and dehydrolinalool derivatives.
Scheme 113: Continuous stilbene isomerisation with continuous recycling of photoredox catalyst.
Scheme 114: Continuous-flow synthesis of compound 494 as developed by Ley et al.
Scheme 115: Selected industrial applications of DA reaction.
Scheme 116: Multistep flow synthesis of the spirocyclic structure 505 via employing DA cycloaddition.
Scheme 117: Continuous-flow DA reaction developed in a plater flow reactor for the preparation of the adduct 508...
Scheme 118: Continuous-flow DA reaction using a silica-supported imidazolidinone organocatalyst.
Scheme 119: Batch vs flow for the DA reaction of (cyclohexa-1,5-dien-1-yloxy)trimethylsilane (513) with acrylon...
Scheme 120: Continuous-flow DA reaction between 510 and 515 using a shell-core droplet system.
Scheme 121: Continuous-flow synthesis of bicyclic systems from benzyne precursors.
Scheme 122: Continuous-flow synthesis of bicyclic scaffolds 527 and 528 for further development of potential ph...
Scheme 123: Continuous-flow inverse-electron hetero-DA reaction to pyridine derivatives such as 531.
Scheme 124: Comparison between batch and flow for the synthesis of pyrimidinones 532–536 via retro-DA reaction ...
Scheme 125: Continuous-flow coupled with ultrasonic system for preparation of ʟ-ascorbic acid derivatives 539 d...
Scheme 126: Two-step continuous-flow synthesis of triazole 543.
Scheme 127: Continuous-flow preparation of triazoles via CuAAC employing 546-based heterogeneous catalyst.
Scheme 128: Continuous-flow synthesis of compounds 558 through A3-coupling and 560 via AgAAC both employing the...
Scheme 129: Continuous-flow photoinduced [2 + 2] cycloaddition for the preparation of bicyclic derivatives of 5...
Scheme 130: Continuous-flow [2 + 2] and [5 + 2] cycloaddition on large scale employing a flow reactor developed...
Scheme 131: Continuous-flow preparation of the tricyclic structures 573 and 574 starting from pyrrole 570 via [...
Scheme 132: Continuous-flow [2 + 2] photocyclization of cinnamates.
Scheme 133: Continuous-flow preparation of cyclobutane 580 on a 5-plates photoreactor.
Scheme 134: Continuous-flow [2 + 2] photocycloaddition under white LED lamp using heterogeneous PCN as photocat...
Figure 11: Picture of the parallel tube flow reactor (PTFR) "The Firefly" developed by Booker-Milburn et al. a...
Scheme 135: Continuous-flow acid-catalysed [2 + 2] cycloaddition between silyl enol ethers and acrylic esters.
Scheme 136: Continuous synthesis of lactam 602 using glass column reactors.
Scheme 137: In situ generation of ketenes for the Staudinger lactam synthesis developed by Ley and Hafner.
Scheme 138: Application of [2 + 2 + 2] cycloadditions in flow employed by Ley et al.
Scheme 139: Examples of FC reactions applied in F&F industry.
Scheme 140: Continuous-flow synthesis of ibuprofen developed by McQuade et al.
Scheme 141: The FC acylation step of Jamison’s three-step ibuprofen synthesis.
Scheme 142: Synthesis of naphthalene derivative 629 via FC acylation in microreactors.
Scheme 143: Flow system for rapid screening of catalysts and reaction conditions developed by Weber et al.
Scheme 144: Continuous-flow system developed by Buorne, Muller et al. for DSD optimisation of the FC acylation ...
Scheme 145: Continuous-flow FC acylation of alkynes to yield β-chlorovinyl ketones such as 638.
Scheme 146: Continuous-flow synthesis of tonalide (619) developed by Wang et al.
Scheme 147: Continuous-flow preparation of acylated arene such as 290 employing Zr4+-β-zeolite developed by Kob...
Scheme 148: Flow system applied on an Aza-FC reaction catalysed by the thiourea catalyst 648.
Scheme 149: Continuous hydroformylation in scCO2.
Scheme 150: Two-step flow synthesis of aldehyde 655 through a sequential Heck reaction and subsequent hydroform...
Scheme 151: Single-droplet (above) and continuous (below) flow reactors developed by Abolhasani et al. for the ...
Scheme 152: Continuous hydroformylation of 1-dodecene (655) using a PFR-CSTR system developed by Sundmacher et ...
Scheme 153: Continuous-flow synthesis of the aldehyde 660 developed by Eli Lilly & Co. [32]. Adapted with permissio...
Scheme 154: Continuous asymmetric hydroformylation employing heterogenous catalst supported on carbon-based sup...
Scheme 155: Examples of acetylation in F&F industry: synthesis of bornyl (S,R,S-664) and isobornyl (S,S,S-664) ...
Scheme 156: Continuous-flow preparation of bornyl acetate (S,R,S-664) employing the oscillating flow reactor.
Scheme 157: Continuous-flow synthesis of geranyl acetate (666) from acetylation of geraniol (343) developed by ...
Scheme 158: 12-Ttungstosilicic acid-supported silica monolith-catalysed acetylation in flow.
Scheme 159: Continuous-flow preparation of cyclopentenone 676.
Scheme 160: Two-stage synthesis of coumarin (90) via acetylation of salicylaldehyde (88).
Scheme 161: Intensification process for acetylation of 5-methoxytryptamine (677) to melatonin (678) developed b...
Scheme 162: Examples of macrocyclic musky odorants both natural (679–681) and synthetic (682 and 683).
Scheme 163: Flow setup combined with microwave for the synthesis of macrocycle 686 via RCM.
Scheme 164: Continuous synthesis of 2,5-dihydro-1H-pyrroles via ring-closing metathesis.
Scheme 165: Continuous-flow metathesis of 485 developed by Leadbeater et al.
Figure 12: Comparison between RCM performed using different routes for the preparation of 696. On the left the...
Scheme 166: Continuous-flow RCM of 697 employed the solid-supported catalyst 698 developed by Grela, Kirschning...
Scheme 167: Continuous-flow RORCM of cyclooctene employing the silica-absorbed catalyst 700.
Scheme 168: Continuous-flow self-metathesis of methyl oleate (703) employing SILP catalyst 704.
Scheme 169: Flow apparatus for the RCM of 697 using a nanofiltration membrane for the recovery and reuse of the...
Scheme 170: Comparison of loadings between RCMs performed with different routes for the synthesis of 709.
Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84
Graphical Abstract
Scheme 1: Synthesis of optically pure 4-phenylchroman-2-one [34].
Scheme 2: Synthesis of (R)-tolterodine [3].
Scheme 3: Catalytic cycle of the Pd(II)-catalysed 1,4-addition of organoboron reagents to enones [3,26,35].
Scheme 4: Enantioselective β-arylation of cyclohexanone [38].
Scheme 5: Application of L2/Pd(OAc)2 in the total synthesis of terpenes [8].
Scheme 6: Plausible catalytic cycle for the addition of phenylboronic acid to 2-cyclohexenone catalysed by L3...
Scheme 7: Microwave-assisted addition of phenylboronic acid to 2-cyclohexenone catalysed by L4/Pd2(dba)3·CHCl3...
Scheme 8: Plausible catalytic cycle of the addition of phenylboronic acid to 2-cyclohexenone catalysed by pal...
Scheme 9: Proposed catalytic cycle for the addition of phenylboronic acids to 2-cyclohexenone catalysed by Pd...
Scheme 10: Usage of addition reactions of boronic acids to various chromones in the syntheses of potentially a...
Scheme 11: Multigram-scale synthesis of ABBV-2222 [6].
Scheme 12: Application of the asymmetric addition of phenylboronic acid to a chromone derivative for the total...
Scheme 13: Plausible catalytic cycle for the addition of phenylboronic acid to 3-methyl-2-cyclohexenone cataly...
Scheme 14: Total syntheses of naturally occurring terpenoids [10,11].
Scheme 15: Use of the L9/Pd(TFA)2 catalytic system for the synthesis of intermediates of biologically active c...
Scheme 16: Usage of a Michael addition catalysed by L9/Pd(TFA)2 in the total synthesis of (–)-ar-tenuifolene [12].
Scheme 17: Synthesis of terpenoids by Michael addition to 3-methyl-2-cyclopentenone [13].
Scheme 18: Rh-catalysed isomerisation of 3-alkyl-3-arylcyclopentanones to 1-tetralones [53].
Scheme 19: Addition reaction of phenylboronic acid to 3-methyl-2-cyclohexenone catalysed by L9/Pd(TFA)2 in wat...
Scheme 20: Micellar nanoreactor PdL10c for the synthesis of flavanones [58].
Scheme 21: Plausible catalytic cycle for the desymmetrisation of polycyclic cyclohexenediones by the addition ...
Scheme 22: Attempt to use the catalytic system L2/Pd(TFA)2 for the addition of phenylboronic acid to 3-methyl-...
Scheme 23: Ring opening of an enantioenriched tetrahydropyran-2-one derivative as alternative strategy to line...
Scheme 24: Synthesis of biologically active compounds from addition products [14-16].
Scheme 25: Chiral 1,10-phenantroline derivative L15 as ligand for the Pd-catalysed addition reactions of pheny...
Scheme 26: The Rh-catalysed addition reaction of phenylboronic acid to a 3-substituted enone [20].
Scheme 27: Underdeveloped methodologies [14,15,65-67].
Scheme 28: Flowchart for the selection of the proper catalytic system.
Beilstein J. Org. Chem. 2021, 17, 873–884, doi:10.3762/bjoc.17.73
Graphical Abstract
Scheme 1: Kinetic mechanisms. In each case E represents the free enzyme, other species starting E are other e...
Figure 1: Reaction progress for “ordered, second” kinetics and the effect of D/Q (e.g., NADH/NAD+) ratio. S0 ...
Figure 2: Effect of the initial starting material concentration and enzyme E value for “ordered, second” kine...
Figure 3: Effects of key enzyme parameters on the fall in product ee during reaction for “ordered, second” ki...
Figure 4: Reaction progress for “ping-pong, second” kinetics, and the effect of the ratio of donor to prochir...
Figure 5: Effect of the key ee decline parameter (eeDP) of the enzyme on the product ee for “ping-pong, secon...
Figure 6: Effects of prochiral substrate concentration and its KM value for “ping-pong, first” kinetics. Inpu...
Figure 7: Effect of eeDP and k−4 · Keq/k4 on the product ee at high conversion for “ping-pong, first” kinetic...
Figure 8: Progress curves for “ping-pong, both” kinetics, diacid esterification. The plot shows the increasin...
Figure 9: Effects on the ee of the product formed early in the reaction for “ping-pong, both” kinetics, diaci...
Figure 10: Increase in the product ee as the reaction proceeds for “ping-pong, both” kinetics, diacid esterifi...
Figure 11: Effects on the ee at high conversion for diacid ester synthesis, “ping-pong, both” kinetics. Parame...
Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125
Graphical Abstract
Figure 1: A) Bar chart of the publications per year for the topics “Photocatalysis” (49,662 instances) and “P...
Figure 2: A) Professor Giacomo Ciamician and Dr. Paolo Silber on their roof laboratory at the University of B...
Scheme 1: PRC trifluoromethylation of N-methylpyrrole (1) using hazardous gaseous CF3I safely in a flow react...
Figure 3: A) Unit cells of the three most common crystal structures of TiO2: rutile, brookite, and anatase. R...
Figure 4: Illustration of the key semiconductor photocatalysis events: 1) A photon with a frequency exceeding...
Figure 5: Photocatalytic splitting of water by oxygen vacancies on a TiO2(110) surface. Reprinted with permis...
Figure 6: Proposed adsorption modes of A) benzene, B) chlorobenzene, C) toluene, D) phenol, E) anisole, and F...
Figure 7: Structures of the sulfonate-containing organic dyes RB5 (3) and MX-5B (4) and the adsorption isothe...
Figure 8: Idealised triclinic unit cell of a g-C3N4 type polymer, displaying possible hopping transport scena...
Figure 9: Idealised structure of a perfect g-C3N4 sheet. The central unit highlighted in red represents one t...
Figure 10: Timeline of the key processes of charge transport following the photoexcitation of g-C3N4, leading ...
Scheme 2: Photocatalytic bifunctionalisation of heteroarenes using mpg-C3N4, with the selected examples 5 and ...
Figure 11: A) Structure of four linear conjugated polymer photocatalysts for hydrogen evolution, displaying th...
Figure 12: Graphical representation of the common methods used to immobilise molecular photocatalysts (PC) ont...
Figure 13: Wireless light emitter-supported TiO2 (TiO2@WLE) HPCat spheres powered by resonant inductive coupli...
Figure 14: Graphical representation of zinc–perylene diimide (Zn-PDI) supramolecular assembly photocatalysis v...
Scheme 3: Upconversion of NIR photons to the UV frequency by NaYF4:Yb,Tm nanocrystals sequentially coated wit...
Figure 15: Types of reactors employed in heterogeneous photocatalysis in flow. A) Fixed bed reactors and the s...
Figure 16: Electrochemical potential of common semiconductor, transition metal, and organic dye-based photocat...
Scheme 4: Possible mechanisms of an immobilised molecular photoredox catalyst by oxidative or reductive quenc...
Scheme 5: Scheme of the CMB-C3N4 photocatalytic decarboxylative fluorination of aryloxyacetic acids, with the...
Scheme 6: Scheme of the g-C3N4 photocatalytic desilylative coupling reaction in flow and proposed mechanism [208].
Scheme 7: Proposed mechanism of the radical cyclisation of unsaturated alkyl 2-bromo-1,3-dicarbonyl compounds...
Scheme 8: N-alkylation of benzylamine and schematic of the TiO2-coated microfluidic device [213].
Scheme 9: Proposed mechanism of the Pt@TiO2 photocatalytic deaminitive cyclisation of ʟ-lysine (23) to ʟ-pipe...
Scheme 10: A) Proposed mechanism for the photocatalytic oxidation of phenylboronic acid (24). B) Photos and SE...
Scheme 11: Proposed mechanism for the DA-CMP3 photocatalytic aza-Henry reaction performed in a continuous flow...
Scheme 12: Proposed mechanism for the formation of the cyclic product 32 by TiO2-NC HPCats in a slurry flow re...
Scheme 13: Reaction scheme for the photocatalytic synthesis of homo and hetero disulfides in flow and scope of...
Scheme 14: Reaction scheme for the MoOx/TiO2 HPCat oxidation of cyclohexane (34) to benzene. The graph shows t...
Scheme 15: Proposed mechanism of the TiO2 HPC heteroarene C–H functionalisation via aryl radicals generated fr...
Scheme 16: Scheme of the oxidative coupling of benzylamines with the HOTT-HATN HPCat and selected examples of ...
Scheme 17: Photocatalysis oxidation of benzyl alcohol (40) to benzaldehyde (41) in a microflow reactor coated ...
Figure 17: Mechanisms of Dexter and Forster energy transfer.
Scheme 18: Continuous flow process for the isomerisation of alkenes with an ionic liquid-immobilised photocata...
Scheme 19: Singlet oxygen synthetic step in the total synthesis of canataxpropellane [265].
Scheme 20: Scheme and proposed mechanism of the singlet oxygen photosensitisation by CMP_X HPCats, with the st...
Scheme 21: Structures of CMP HPCat materials applied by Vilela and co-workers for the singlet oxygen photosens...
Scheme 22: Polyvinylchloride resin-supported TDCPP photosensitisers applied for singlet oxygen photosensitisat...
Scheme 23: Structure of the ionically immobilised TPP photosensitiser on amberlyst-15 ion exchange resins (TPP...
Scheme 24: Photosensitised singlet oxygen oxidation of citronellol (46) in scCO2, with automatic phase separat...
Scheme 25: Schematic of PS-Est-BDP-Cl2 being applied for singlet oxygen photosensitisation in flow. A) Pseudo-...
Scheme 26: Reaction scheme of the singlet oxygen oxidation of furoic acid (54) using a 3D-printed microfluidic...
Figure 18: A) Photocatalytic bactericidal mechanism by ROS oxidative cleavage of membrane lipids (R = H, amino...
Figure 19: A) Suggested mechanisms for the aqueous pollutant degradation by TiO2 in a slurry flow reactor [284-287]. B)...
Figure 20: Schematic of the flow system used for the degradation of aqueous oxytetracycline (56) solutions [215]. M...
Scheme 27: Degradation of a salicylic acid (57) solution by a coupled solar photoelectro-Fenton (SPEF) process...
Figure 21: A) Schematic flow diagram using the TiO2-coated NETmix microfluidic device for an efficient mass tr...
Beilstein J. Org. Chem. 2020, 16, 125–134, doi:10.3762/bjoc.16.14
Graphical Abstract
Figure 1: a) The potent tubulin inhibitor colchicine as a lead scaffold led to the development of the HOTub g...
Figure 2: Chemical structures of HITubs. Key variations with respect to HITub-4 are highlighted in dashed box...
Figure 3: Photocharacterisation of HITub-4. a) Photochemical and thermal isomerisation. b) UV–vis spectra aft...
Figure 4: a) Resazurin reduction assay for HITub-4 and nocodazole in HeLa cells (n = 3), demonstrating the di...
Figure 5: Confocal microscopy images of immunofluorescently labelled MT networks after treatment with HITubs ...
Figure 6: Cell cycle analysis of HITub-4-treated cells. a) and b) (Z)-HITub-4 caused significant G2/M arrest ...
Beilstein J. Org. Chem. 2019, 15, 2590–2602, doi:10.3762/bjoc.15.252
Graphical Abstract
Figure 1: Terpene constituents 1–9 found in geranium and bergamot oils and specified odours of individual com...
Figure 2: Other selected mono- and sesquiterpenes (10–26) as fragrance materials [6].
Figure 3: Main constituents of natural iris oil: irone (27).
Scheme 1: First synthesis of ionone (30) [11].
Scheme 2: First synthesis of Ambrelux (32) [14].
Scheme 3: Industrial synthesis of myrcene (1) by pyrolysis of β-pinene (8).
Scheme 4: First synthesis of Iso E Super® (33), Iso E Super Plus® (34) and Georgywood® (35) as a mixture of i...
Figure 4: Iso E Super® region of GC spectra of Molecule 01 (left, 75 €–100 € per 100 mL; march 2019), a low-p...
Scheme 5: First synthetic route to (−)-Georgywood® (35) by Corey and Hong [33].
Scheme 6: First synthetic route to the odour-active (+)-enantiomer of Iso E Super Plus® (+)-34 [33].
Scheme 7: Analysis of the isomerisation process and formation of products. Most importantly, Iso E Super® (33...
Scheme 8: Isomerisation using additives such as alcohols or carboxylic acids. The product with the γ-position...
Scheme 9: Iso E Super Plus® (34) can undergo a third cyclisation to tetrahydrofuran 59 through compound rac-53...
Figure 5: (Adapted from ref. [8]) Ionone (30, 1893, odour threshold: 0.8 ng L−1), koavone (1982, odour threshold...
Figure 6: Branched, terpene-like cyclohexene derivatives, that are synthetic fragrance components: 60: Iso da...
Scheme 10: New unnatural terpenoid 70 from unnatural farnesyl pyrophosphate derivative 69 and comparison with ...
Beilstein J. Org. Chem. 2019, 15, 2184–2190, doi:10.3762/bjoc.15.215
Graphical Abstract
Scheme 1: Mechanism of the ADS-catalysed conversion of FDP (2) to amorpha-4,11-diene (3), a biosynthetic prec...
Scheme 2: Synthesis of 8-methoxy-FDP (11) and 12-methoxy-FDP (12) (for full synthesis details see Supporting Information File 1).
Figure 1: Total-ion chromatogram of the pentane extractable products formed in an incubation of ADS with 8-me...
Figure 2: 1H NMR spectrum (500 MHz, CDCl3) of the 8-methoxy-γ-humulene (20) generated by ADS from 8-methoxy-F...
Scheme 3: Potential mechanisms for the ADS-catalysed conversion of 8-methoxy-FDP (11) to 8-methoxy-γ-humulene...
Figure 3: Total-ion chromatogram of the pentane extractable products formed in an incubation of ADS with 12-m...
Figure 4: 1H NMR spectrum (400 MHz, CDCl3) of 12-methoxy-β-sesquiphellandrene (26) and 12-methoxyzingiberene (...
Scheme 4: Possible mechanisms for the ADS-catalysed conversion of 12-methoxy-FDP (12) to 12-methoxy-β-sesquip...
Beilstein J. Org. Chem. 2019, 15, 2170–2183, doi:10.3762/bjoc.15.214
Graphical Abstract
Figure 1: Selisistat (1) and hit compound GW435821X (2a).
Scheme 1: Reagents and conditions: a) appropriate boronic acid, Pd(PPh3)4, Na2CO3, DMF, H2O, microwave, 15 mi...
Scheme 2: Reagents and conditions: a) Pd2(dba)3 or Pd(OAc)2, P(o-tol)3, TEA, DMF, 120–140 °C, 0.7–24 h, 11–75...
Figure 2: (Left) UV–vis spectrum of 2b 50 µM in 5% DMSO (v/v) in assay buffer after varying durations of irra...
Figure 3: (Left) LC chromatogram of the LC–HRMS analysis of 2b after varying durations of irradiation with 25...
Scheme 3: Photocyclization and oxidation reaction of 2b upon UV irradiation.
Figure 4: Calculated and experimental absorption spectra of compounds (E)-2b-B (A), (Z)-2b-A (B), and product...
Scheme 4: Reagents and conditions: a) 4-fluoroaniline, oxone, HAc, 60 °C, 14 d, 42%; b) NH3, MeOH, rt, 3 d, 9...
Figure 5: (Left) UV–vis spectrum of 11, 50 µM in 5% DMSO (v/v), in assay buffer at the thermal equilibrium an...
Beilstein J. Org. Chem. 2019, 15, 2013–2019, doi:10.3762/bjoc.15.197
Graphical Abstract
Scheme 1: a) Azobenzenes A1–3 employed in this study. b) U-shaped anthracene halogen bond acceptor bearing tw...
Figure 1: Electrostatic potential map at different isodensity values (B3LYP/ def2/TZVP/DGZVP optimized geomet...
Figure 2: Top: Vertical electronic absorption spectra of a) A2 and b) A3, calculated using TD-B3LYP/def2-TZVP...
Figure 3: a) Space-filling model of U1···A2. The kinked alignment of both the lutidine units of U1 and the az...
Beilstein J. Org. Chem. 2019, 15, 1815–1821, doi:10.3762/bjoc.15.175
Graphical Abstract
Figure 1: Structures of the norbornadiene platform 1a and the quadricyclane platform 1b (for geometry coordin...
Scheme 1: Syntheses of the norbornadiene TATA platform 1 and TOTA platform 3. a) TMS-acetylene, Pd(PPh3)4, Cu...
Scheme 2: Synthesis of methylphenylnorbornadiene platform 2. a) Pd(PPh3)4, Na2CO3, toluene, EtOH, H2O, N2, re...
Figure 2: UV–vis spectra of platform molecules 1 (a), 2 (b) and 3 (c) (in THF at rt): Norbornadiene (black), ...
Figure 3: 1H NMR spectra of 1 in deuterated oxygen containing deuterated benzene (left) and degassed deuterat...
Figure 4: Determination of the thermal isomerization rate k of 1b (QC) by 1H NMR spectroscopy (toluene, 293.5...
Figure 5: (a) STM image of self-assembled monolayers of compound 1 on Au(111) (40 × 40 nm2, It = 0.05 nA, Ubi...
Beilstein J. Org. Chem. 2019, 15, 1181–1193, doi:10.3762/bjoc.15.115
Graphical Abstract
Figure 1: Whole-genome phylogenetic analyses of Streptomyces species. Rooted maximum likelihood phylogeny of ...
Figure 2: Structures of the products of the ten most abundant terpene synthases in Streptomyces.
Scheme 1: Mechanism for the cyclisation of FPP to geosmin.
Scheme 2: Biosynthesis of 2-MIB (2). First, GPP is methylated to 14 by a SAM-dependent methyltransferase, fol...
Scheme 3: Oxidation products derived from 3 by the cytochrome P450 monooxygenase that is genetically clustere...
Scheme 4: Biosynthesis of cyclooctatin (20) from 7.
Figure 3: Phylogenetic tree of geosmin synthases. Unrooted maximum likelihood phylogenetic tree of 92 geosmin...
Figure 4: Phylogenetic tree of 2-MIB synthases. Unrooted maximum likelihood phylogenetic tree of 48 2-MIB syn...
Figure 5: Phylogenetic tree of epi-isozizaene synthases. Unrooted maximum likelihood phylogenetic tree of 42 ...
Beilstein J. Org. Chem. 2019, 15, 789–794, doi:10.3762/bjoc.15.75
Graphical Abstract
Figure 1: Structures of achiral terpenes: (E)-β-farnesene (1), α-humulene (2), 1,8-cineol (3) and sodorifen (4...
Figure 2: A) Total ion chromatogram of a hexane extract from the incubation of FPP with BbS and B) EI mass sp...
Scheme 1: Cyclisation mechanism to 5 involving either the intermediates (R)-NPP and (S)-A (path A) or (S)-NPP...
Figure 3: Total ion chromatograms of hexane extracts from incubation experiments with BbS and A) (R)-NPP, B) (...
Figure 4: Hypothetical BbS active site comparable conformational folds of A) FPP, B) (R)- and C) (S)-NPP expl...