A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water
- Piyali Sarkar,
- Sayan Sarkar and
- Pradyut Ghosh
Beilstein J. Org. Chem. 2019, 15, 1505–1514, doi:10.3762/bjoc.15.152
Graphical Abstract
Figure 1: Bis-amido-tris-amine macrocycle BATA-MC.
Figure 2: (a) Number distribution plot with particle size in DLS, (b) SEM image and (c) TEM image showing the...
Figure 3: Dependence of the yield of compound 4a on the reaction time using BATA-MC.
Figure 4: Yields of product 4a at different catalyst loading.
Scheme 1: BATA-MC-catalyzed synthesis of 4,5-dihydropyrrolo[2,3,4-kl]acridinones.
Scheme 2: BATA-MC-catalyzed synthesis of pyrrolo[2,3,4-kl]acridinone derivatives.
Figure 5: X-ray single crystal structure of 4d (CCDC 1898008).
Scheme 3: Probable mechanism illustrated for the synthesis of 4a using BATA-MC. For the sake of simplicity, w...
Figure 6: Representation of BATA-MC nanoreactor.
Figure 7: The reusability of the nanoreactor for the synthesis of 4a.
Superelectrophilic carbocations: preparation and reactions of a substrate with six ionizable groups
- Sean H. Kennedy,
- Makafui Gasonoo and
- Douglas A. Klumpp
Beilstein J. Org. Chem. 2019, 15, 1515–1520, doi:10.3762/bjoc.15.153
Graphical Abstract
Scheme 1: Superelectrophilic species.
Scheme 2: Synthesis of diol substrate 9.
Scheme 3: Isolated yields of products from diol 9.
Scheme 4: Proposed mechanisms leading to products 10 and 11.
Scheme 5: Products and relative yields from the reaction of alcohol 18 with CF3SO3H and C6H6 [12].
Scheme 6: Comparison of superelectrophilic carbocations (3–5 and 14) and their chemistry.
Scheme 7: DFT calculated relative energies of pentacations 16 and 21 [14].
Mechanochemistry II
- José G. Hernández
Beilstein J. Org. Chem. 2019, 15, 1521–1522, doi:10.3762/bjoc.15.154
A novel three-component reaction between isocyanides, alcohols or thiols and elemental sulfur: a mild, catalyst-free approach towards O-thiocarbamates and dithiocarbamates
- András György Németh,
- György Miklós Keserű and
- Péter Ábrányi-Balogh
Beilstein J. Org. Chem. 2019, 15, 1523–1533, doi:10.3762/bjoc.15.155
Graphical Abstract
Scheme 1: Synthetic routes to O-thiocarbamates and dithiocarbamates.
Scheme 2: Substrate scope of isocyanides. aReaction conditions: 1 (1 mmol), S8 (2 mmol), 2a (2mmol), NaH (2 m...
Scheme 3: Substrate scope of alcohols. Reaction conditions: 1a (1 mmol), S8 (2 mmol), 2 (2mmol), NaH (2 mmol)...
Scheme 4: Substrate scope of thiols. Reaction conditions: 1a (1 mmol), S8 (1.2 mmol), 4 (2 mmol), NaOH (2 mmo...
Scheme 5: Scaled-up synthesis for 3a.
Scheme 6: Multicomponent domino synthesis of quinazolinone 7.
Scheme 7: Control experiments.
Scheme 8: Proposed mechanism.
An azobenzene container showing a definite folding – synthesis and structural investigation
- Abdulselam Adam,
- Saber Mehrparvar and
- Gebhard Haberhauer
Beilstein J. Org. Chem. 2019, 15, 1534–1544, doi:10.3762/bjoc.15.156
Graphical Abstract
Figure 1: Some examples for artificial C2- and C3-symmetric platforms based on Lissoclinum cyclopeptide alkal...
Figure 2: a) Principle of a chiral foldable platform and container based on Lissoclinum cyclopeptide alkaloid...
Scheme 1: Synthesis of the chiral foldable container 10. Reaction conditions: i) FDPP, iPr2NEt, CH3CN, 90%; i...
Figure 3: Molecular structures of trans,trans-10 (left), cis,trans-10 (middle) and cis,cis-10 (right) calcula...
Figure 4: UV spectra of the foldable container 10 in acetonitrile after synthesis (blue), after irradiation w...
Figure 5: Section from the 1H NMR spectra of the foldable container 10 in MeOD at 600 MHz: a) after synthesis...
Figure 6: HPLC spectra (ReproSil Phenyl, 5 μm, 250 × 8 mm; methanol) of trans,trans-10 (blue), cis,trans-10 (...
Figure 7: CD spectra of trans,trans-10 (blue), cis,trans-10 (green), and cis,cis-10 (red) in methanol (c = 3....
Figure 8: DOSY NMR spectra (500 MHz in MeOD at 25 °C) of the foldable container 10 after synthesis (left) and...
Molecular basis for the plasticity of aromatic prenyltransferases in hapalindole biosynthesis
- Takayoshi Awakawa and
- Ikuro Abe
Beilstein J. Org. Chem. 2019, 15, 1545–1551, doi:10.3762/bjoc.15.157
Graphical Abstract
Figure 1: The reactions of aromatic PTases.
Figure 2: The reactions catalyzed by AmbP1 (A) and AmbP3 (B).
Figure 3: The overall structure of apo-AmbP1 (A), the Mg2+-free structure (B), and the Mg2+-bound structure (...
Figure 4: The active site structure of AmbP1. 1 and GSPP were bound in the active site without Mg2+ (A, Mg2+-...
Figure 5: The active site structure of AmbP3 with substrates. The AmbP3 structure in complex with hapalindole...
Figure 6: Multiple amino acid sequence alignment of AmbP1, AmbP3, and other ABBA PTases, visualized by ESPrip...
Transient and intermediate carbocations in ruthenium tetroxide oxidation of saturated rings
- Manuel Pedrón,
- Laura Legnani,
- Maria-Assunta Chiacchio,
- Pierluigi Caramella,
- Tomás Tejero and
- Pedro Merino
Beilstein J. Org. Chem. 2019, 15, 1552–1562, doi:10.3762/bjoc.15.158
Graphical Abstract
Scheme 1: Oxidation of alkanes with RuO4.
Scheme 2: Mechanisms for RuO4 oxidation of alkanes.
Scheme 3: Oxidation of saturated five-membered (hetero)cyclic compounds.
Scheme 4: Rate-limiting step for the oxidation of cyclopentane (R1), tetrahydrofuran (R2) and tetrahydrothiop...
Figure 1: Optimized (B3LYP-d3bj/Def2SVP/cpcm=MeCN) geometries of transition structures corresponding to the o...
Figure 2: ELF analysis for the oxidation of cyclopentane (R1). Left: evolution of the electron population alo...
Figure 3: ELF analysis for the oxidation of tetrahydrofuran (R2, A) and tetrahydrothiophene (R3, B). Left: ev...
Figure 4: ELF assignment of electrons to the Ru environment. C(Ru) corresponds to a monosynaptic core basin a...
Scheme 5: Rate-limiting step for the oxidation of N-methyl- and N-benzylpyrrolidines R4 and R5, respectively.
Figure 5: Energy profile for the oxidation of R4 and R5. Relative energies, calculated at the B3LYP-d3bj/Def2...
Figure 6: Optimized (B3LYP-d3bj/Def2SVP/cpcm=water) transition structures for the oxidation of R4 and R5.
Synthesis of ([1,2,4]triazolo[4,3-a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-exo-dig cyclization
- Aleksandr S. Krylov,
- Artem A. Petrosian,
- Julia L. Piterskaya,
- Nataly I. Svintsitskaya and
- Albina V. Dogadina
Beilstein J. Org. Chem. 2019, 15, 1563–1568, doi:10.3762/bjoc.15.159
Graphical Abstract
Scheme 1: Synthetic approaches to [1,2,4]triazolo[4,3-a]pyridines.
Scheme 2: Synthesis of 3-methylphosphonylated [1,2,4]triazolo[4,3-a]pyridines. Reaction conditions: 1 (1 mmol...
Scheme 3: Synthesis of methylphosphonylated 6(8)-nitro-[1,2,4]triazolo[4,3-a]pyridines and 6(8)-nitro-[1,2,4]...
Scheme 4: Acid-promoted Dimroth rearrangement pathway.
Scheme 5: Synthesis of phosphonylated [1,2,4]triazolo[4,3-a]quinolines and [1,2,4]triazolo[3,4-a]isoquinoline...
Scheme 6: Plausible reaction pathway.
Enantioselective PCCP Brønsted acid-catalyzed aza-Piancatelli rearrangement
- Gabrielle R. Hammersley,
- Meghan F. Nichol,
- Helena C. Steffens,
- Jose M. Delgado,
- Gesine K. Veits and
- Javier Read de Alaniz
Beilstein J. Org. Chem. 2019, 15, 1569–1574, doi:10.3762/bjoc.15.160
Graphical Abstract
Figure 1: Proposed mechanism of the asymmetric aza-Piancatelli reaction.
Scheme 1: Asymmetric aza-Piancatelli rearrangement with a range of substituted anilines. *To simplify the pur...
Scheme 2: Asymmetric aza-Piancatelli rearrangement with a range of substituted furylcarbinols. *To simplify t...
Synthesis of 9-O-arylated berberines via copper-catalyzed CAr–O coupling reactions
- Qiaoqiao Teng,
- Xinhui Zhu,
- Qianqian Guo,
- Weihua Jiang,
- Jiang Liu and
- Qi Meng
Beilstein J. Org. Chem. 2019, 15, 1575–1580, doi:10.3762/bjoc.15.161
Graphical Abstract
Scheme 1: Synthetic pathway of 9-O-R BBR.
Scheme 2: Resonance of berberrubine leading to the failure of direct BBRB cross coupling.
Scheme 3: 9-O-Aryl berberine scope via cross-coupling reaction.
Scheme 4: 9-O-Ph-linked berberine dimer through double cross-coupling reaction.
Synthesis and conformational preferences of short analogues of antifreeze glycopeptides (AFGP)
- Małgorzata Urbańczyk,
- Michał Jewgiński,
- Joanna Krzciuk-Gula,
- Jerzy Góra,
- Rafał Latajka and
- Norbert Sewald
Beilstein J. Org. Chem. 2019, 15, 1581–1591, doi:10.3762/bjoc.15.162
Graphical Abstract
Figure 1: Glycosylated building blocks prepared for solid phase peptide synthesis (SPPS).
Scheme 1: A) Modification of Fmoc-Sieber-PS resin: a. piperidine in DMF (20% v/v), rt; 3 × 10 min; b. o-NBS-C...
Figure 2: Model AFGP analogues.
Figure 3: Conformational preferences of investigated glycopeptides.
Figure 4: Conformational preferences of monosaccharide moiety. A) cluster 1 for glycopeptide 3, B) cluster 1 ...
Water inside β-cyclodextrin cavity: amount, stability and mechanism of binding
- Stiliyana Pereva,
- Valya Nikolova,
- Silvia Angelova,
- Tony Spassov and
- Todor Dudev
Beilstein J. Org. Chem. 2019, 15, 1592–1600, doi:10.3762/bjoc.15.163
Graphical Abstract
Figure 1: M062X/6-31G(d,p) optimized structure of nonhydrated β-CD in two projections (left: a side view and ...
Figure 2: Schematic representation of β-CD–nH2O complexes (where n = 1–12) with water molecules/clusters loca...
Figure 3: M062X/6-31G(d,p) optimized structures of the most stable (a structures from Figure 2) β-CD–nH2O complexes (n...
Figure 4: Graphical model of the β-CD electron density (isovalue = 0.002), mapped with electrostatic potentia...
Figure 5: Thermal behavior of β-CD.
Figure 6: Thermal behavior of β-CD: TG curves (a) and DTA scans (b).
Synthesis, enantioseparation and photophysical properties of planar-chiral pillar[5]arene derivatives bearing fluorophore fragments
- Guojuan Li,
- Chunying Fan,
- Guo Cheng,
- Wanhua Wu and
- Cheng Yang
Beilstein J. Org. Chem. 2019, 15, 1601–1611, doi:10.3762/bjoc.15.164
Graphical Abstract
Scheme 1: Preparation of A1/A2-difunctionalized pillar[5]arenes (P5A-DPA and P5A-Py) by click reactions. Reag...
Figure 1: UV–vis absorption (a) and fluorescence emission spectra (b) of Py-6, P5A-Py (λex = 420 nm) and DPA-6...
Figure 2: (a) Fluorescence decay curves of Py-6 and P5A-Py at 450 nm and (b) fluorescence decay curves of DPA...
Figure 3: (a) Chiral HPLC traces of P5A-DPA, (b), (c) the first and second fractions of P5A-DPA, detected by ...
Figure 4: (a) CD, (b) UV–vis and (c) fluorescence spectra of the RP5A-DPA (20 μM) in THF and THF/H2O solvent ...
Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage
- Gagandeep Kour Reen,
- Ashok Kumar and
- Pratibha Sharma
Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165
Graphical Abstract
Figure 1: Various drugs having IP nucleus.
Figure 2: Participation percentage of various TMs for the syntheses of IPs.
Scheme 1: CuI–NaHSO4·SiO2-catalyzed synthesis of imidazo[1,2-a]pyridines.
Scheme 2: Experimental examination of reaction conditions.
Scheme 3: One-pot tandem reaction for the synthesis of 2-haloimidazopyridines.
Scheme 4: Mechanistic scheme for the synthesis of 2-haloimidazopyridine.
Scheme 5: Copper-MOF-catalyzed three-component reaction (3-CR) for imidazo[1,2-a]pyridines.
Scheme 6: Mechanism for copper-MOF-driven synthesis.
Scheme 7: Heterogeneous synthesis via titania-supported CuCl2.
Scheme 8: Mechanism involving oxidative C–H functionalization.
Scheme 9: Heterogeneous synthesis of IPs.
Scheme 10: One-pot regiospecific synthesis of imidazo[1,2-a]pyridines.
Scheme 11: Vinyl azide as an unprecedented substrate for imidazo[1,2-a]pyridines.
Scheme 12: Radical pathway.
Scheme 13: Cu(I)-catalyzed transannulation approach for imidazo[1,5-a]pyridines.
Scheme 14: Plausible radical pathway for the synthesis of imidazo[1,5-a]pyridines.
Scheme 15: A solvent-free domino reaction for imidazo[1,2-a]pyridines.
Scheme 16: Cu-NPs-mediated synthesis of imidazo[1,2-a]pyridines.
Scheme 17: CuI-catalyzed synthesis of isoxazolylimidazo[1,2-a]pyridines.
Scheme 18: Functionalization of 4-bromo derivative via Sonogashira coupling reaction.
Scheme 19: A plausible reaction pathway.
Scheme 20: Cu(I)-catalyzed intramolecular oxidative C–H amidation reaction.
Scheme 21: One-pot synthetic reaction for imidazo[1,2-a]pyridine.
Scheme 22: Plausible reaction mechanism.
Scheme 23: Cu(OAc)2-promoted synthesis of imidazo[1,2-a]pyridines.
Scheme 24: Mechanism for aminomethylation/cycloisomerization of propiolates with imines.
Scheme 25: Three-component synthesis of imidazo[1,2-a]pyridines.
Figure 3: Scope of pyridin-2(1H)-ones and acetophenones.
Scheme 26: CuO NPS-promoted A3 coupling reaction.
Scheme 27: Cu(II)-catalyzed C–N bond formation reaction.
Scheme 28: Mechanism involving Chan–Lam/Ullmann coupling.
Scheme 29: Synthesis of formyl-substituted imidazo[1,2-a]pyridines.
Scheme 30: A tandem sp3 C–H amination reaction.
Scheme 31: Probable mechanistic approach.
Scheme 32: Dual catalytic system for imidazo[1,2-a]pyridines.
Scheme 33: Tentative mechanism.
Scheme 34: CuO/CuAl2O4/ᴅ-glucose-promoted 3-CCR.
Scheme 35: A tandem CuOx/OMS-2-based synthetic strategy.
Figure 4: Biomimetic catalytic oxidation in the presence of electron-transfer mediators (ETMs).
Scheme 36: Control experiment.
Scheme 37: Copper-catalyzed C(sp3)–H aminatin reaction.
Scheme 38: Reaction of secondary amines.
Scheme 39: Probable mechanistic pathway.
Scheme 40: Coupling reaction of α-azidoketones.
Scheme 41: Probable pathway.
Scheme 42: Probable mechanism with free energy calculations.
Scheme 43: MCR for cyanated IP synthesis.
Scheme 44: Substrate scope for the reaction.
Scheme 45: Reaction mechanism.
Scheme 46: Probable mechanistic pathway for Cu/ZnAl2O4-catalyzed reaction.
Scheme 47: Copper-catalyzed double oxidative C–H amination reaction.
Scheme 48: Application towards different coupling reactions.
Scheme 49: Reaction mechanism.
Scheme 50: Condensation–cyclization approach for the synthesis of 1,3-diarylated imidazo[1,5-a]pyridines.
Scheme 51: Optimized reaction conditions.
Scheme 52: One-pot 2-CR.
Scheme 53: One-pot 3-CR without the isolation of chalcone.
Scheme 54: Copper–Pybox-catalyzed cyclization reaction.
Scheme 55: Mechanistic pathway catalyzed by Cu–Pybox complex.
Scheme 56: Cu(II)-promoted C(sp3)-H amination reaction.
Scheme 57: Wider substrate applicability for the reaction.
Scheme 58: Plausible reaction mechanism.
Scheme 59: CuI assisted C–N cross-coupling reaction.
Scheme 60: Probable reaction mechanism involving sp3 C–H amination.
Scheme 61: One-pot MCR-catalyzed by CoFe2O4/CNT-Cu.
Scheme 62: Mechanistic pathway.
Scheme 63: Synthetic scheme for 3-nitroimidazo[1,2-a]pyridines.
Scheme 64: Plausible mechanism for CuBr-catalyzed reaction.
Scheme 65: Regioselective synthesis of halo-substituted imidazo[1,2-a]pyridines.
Scheme 66: Synthesis of 2-phenylimidazo[1,2-a]pyridines.
Scheme 67: Synthesis of diarylated compounds.
Scheme 68: CuBr2-mediated one-pot two-component oxidative coupling reaction.
Scheme 69: Decarboxylative cyclization route to synthesize 1,3-diarylimidazo[1,5-a]pyridines.
Scheme 70: Mechanistic pathway.
Scheme 71: C–H functionalization reaction of enamines to produce diversified heterocycles.
Scheme 72: A plausible mechanism.
Scheme 73: CuI-promoted aerobic oxidative cyclization reaction of ketoxime acetates and pyridines.
Scheme 74: CuI-catalyzed pathway for the formation of imidazo[1,2-a]pyridine.
Scheme 75: Mechanistic pathway.
Scheme 76: Mechanistic rationale for the synthesis of products.
Scheme 77: Copper-catalyzed synthesis of vinyloxy-IP.
Scheme 78: Regioselective product formation with propiolates.
Scheme 79: Proposed mechanism for vinyloxy-IP formation.
Scheme 80: Regioselective synthesis of 3-hetero-substituted imidazo[1,2-a]pyridines with different reaction su...
Scheme 81: Mechanistic pathway.
Scheme 82: CuI-mediated synthesis of 3-formylimidazo[1,2-a]pyridines.
Scheme 83: Radical pathway for 3-formylated IP synthesis.
Scheme 84: Pd-catalyzed urea-cyclization reaction for IPs.
Scheme 85: Pd-catalyzed one-pot-tandem amination and intramolecular amidation reaction.
Figure 5: Scope of aniline nucleophiles.
Scheme 86: Pd–Cu-catalyzed Sonogashira coupling reaction.
Scheme 87: One-pot amide coupling reaction for the synthesis of imidazo[4,5-b]pyridines.
Scheme 88: Urea cyclization reaction for the synthesis of two series of pyridines.
Scheme 89: Amidation reaction for the synthesis of imidazo[4,5-b]pyridines.
Figure 6: Amide scope.
Scheme 90: Pd NPs-catalyzed 3-component reaction for the synthesis of 2,3-diarylated IPs.
Scheme 91: Plausible mechanistic pathway for Pd NPs-catalyzed MCR.
Scheme 92: Synthesis of chromenoannulated imidazo[1,2-a]pyridines.
Scheme 93: Mechanism for the synthesis of chromeno-annulated IPs.
Scheme 94: Zinc oxide NRs-catalyzed synthesis of imidazo[1,2-a]azines/diazines.
Scheme 95: Zinc oxide-catalyzed isocyanide based GBB reaction.
Scheme 96: Reaction pathway for ZnO-catalyzed GBB reaction.
Scheme 97: Mechanistic pathway.
Scheme 98: ZnO NRs-catalyzed MCR for the synthesis of imidazo[1,2-a]azines.
Scheme 99: Ugi type GBB three-component reaction.
Scheme 100: Magnetic NPs-catalyzed synthesis of imidazo[1,2-a]pyridines.
Scheme 101: Regioselective synthesis of 2-alkoxyimidazo[1,2-a]pyridines catalyzed by Fe-SBA-15.
Scheme 102: Plausible mechanistic pathway for the synthesis of 2-alkoxyimidazopyridine.
Scheme 103: Iron-catalyzed synthetic approach.
Scheme 104: Iron-catalyzed aminooxygenation reaction.
Scheme 105: Mechanistic pathway.
Scheme 106: Rh(III)-catalyzed double C–H activation of 2-substituted imidazoles and alkynes.
Scheme 107: Plausible reaction mechanism.
Scheme 108: Rh(III)-catalyzed non-aromatic C(sp2)–H bond activation–functionalization for the synthesis of imid...
Scheme 109: Reactivity and selectivity of different substrates.
Scheme 110: Rh-catalyzed direct C–H alkynylation by Li et al.
Scheme 111: Suggested radical mechanism.
Scheme 112: Scandium(III)triflate-catalyzed one-pot reaction and its mechanism for the synthesis of benzimidazo...
Scheme 113: RuCl3-assisted Ugi-type Groebke–Blackburn condensation reaction.
Scheme 114: C-3 aroylation via Ru-catalyzed two-component reaction.
Scheme 115: Regioselective synthetic mechanism.
Scheme 116: La(III)-catalyzed one-pot GBB reaction.
Scheme 117: Mechanistic approach for the synthesis of imidazo[1,2-a]pyridines.
Scheme 118: Synthesis of imidazo[1,2-a]pyridine using LaMnO3 NPs under neat conditions.
Scheme 119: Mechanistic approach.
Scheme 120: One-pot 3-CR for regioselective synthesis of 2-alkoxy-3-arylimidazo[1,2-a]pyridines.
Scheme 121: Formation of two possible products under optimization of the catalysts.
Scheme 122: Mechanistic strategy for NiFe2O4-catalyzed reaction.
Scheme 123: Two-component reaction for synthesizing imidazodipyridiniums.
Scheme 124: Mechanistic scheme for the synthesis of imidazodipyridiniums.
Scheme 125: CuI-catalyzed arylation of imidazo[1,2-a]pyridines.
Scheme 126: Mechanism for arylation reaction.
Scheme 127: Cupric acetate-catalyzed double carbonylation approach.
Scheme 128: Radical mechanism for double carbonylation of IP.
Scheme 129: C–S bond formation reaction catalyzed by cupric acetate.
Scheme 130: Cupric acetate-catalyzed C-3 formylation approach.
Scheme 131: Control experiments for signifying the role of DMSO and oxygen.
Scheme 132: Mechanism pathway.
Scheme 133: Copper bromide-catalyzed CDC reaction.
Scheme 134: Extension of the substrate scope.
Scheme 135: Plausible radical pathway.
Scheme 136: Transannulation reaction for the synthesis of imidazo[1,5-a]pyridines.
Scheme 137: Plausible reaction pathway for denitrogenative transannulation.
Scheme 138: Cupric acetate-catalyzed C-3 carbonylation reaction.
Scheme 139: Plausible mechanism for regioselective C-3 carbonylation.
Scheme 140: Alkynylation reaction at C-2 of 3H-imidazo[4,5-b]pyridines.
Scheme 141: Two-way mechanism for C-2 alkynylation of 3H-imidazo[4,5-b]pyridines.
Scheme 142: Palladium-catalyzed SCCR approach.
Scheme 143: Palladium-catalyzed Suzuki coupling reaction.
Scheme 144: Reaction mechanism.
Scheme 145: A phosphine free palladium-catalyzed synthesis of C-3 arylated imidazopyridines.
Scheme 146: Palladium-mediated Buchwald–Hartwig cross-coupling reaction.
Figure 7: Structure of the ligands optimized.
Scheme 147: Palladium acetate-catalyzed direct arylation of imidazo[1,2-a]pyridines.
Scheme 148: Palladium acetate-catalyzed mechanistic pathway.
Scheme 149: Palladium acetate-catalyzed regioselective arylation reported by Liu and Zhan.
Scheme 150: Mechanism for selective C-3 arylation of IP.
Scheme 151: Pd(II)-catalyzed alkenylation reaction with styrenes.
Scheme 152: Pd(II)-catalyzed alkenylation reaction with acrylates.
Scheme 153: A two way mechanism.
Scheme 154: Double C–H activation reaction catalyzed by Pd(OAc)2.
Scheme 155: Probable mechanism.
Scheme 156: Palladium-catalyzed decarboxylative coupling.
Scheme 157: Mechanistic cycle for decarboxylative arylation reaction.
Scheme 158: Ligand-free approach for arylation of imidazo[1,2-a]pyridine-3-carboxylic acids.
Scheme 159: Mechanism for ligandless arylation reaction.
Scheme 160: NHC-Pd(II) complex assisted arylation reaction.
Scheme 161: C-3 arylation of imidazo[1,2-a]pyridines with aryl bromides catalyzed by Pd(OAc)2.
Scheme 162: Pd(II)-catalyzed C-3 arylations with aryl tosylates and mesylates.
Scheme 163: CDC reaction for the synthesis of imidazo[1,2-a]pyridines.
Scheme 164: Plausible reaction mechanism for Pd(OAc)2-catalyzed synthesis of imidazo[1,2-a]pyridines.
Scheme 165: Pd-catalyzed C–H amination reaction.
Scheme 166: Mechanism for C–H amination reaction.
Scheme 167: One-pot synthesis for 3,6-di- or 2,3,6-tri(hetero)arylimidazo[1,2-a]pyridines.
Scheme 168: C–H/C–H cross-coupling reaction of IPs and azoles catalyzed by Pd(II).
Scheme 169: Mechanistic cycle.
Scheme 170: Rh-catalyzed C–H arylation reaction.
Scheme 171: Mechanistic pathway for C–H arylation of imidazo[1,2-a]pyridine.
Scheme 172: Rh(III)-catalyzed double C–H activation of 2-phenylimidazo[1,2-a]pyridines and alkynes.
Scheme 173: Rh(III)-catalyzed mechanistic pathway.
Scheme 174: Rh(III)-mediated oxidative coupling reaction.
Scheme 175: Reactions showing functionalization of the product obtained by the group of Kotla.
Scheme 176: Mechanism for Rh(III)-catalyzed oxidative coupling reaction.
Scheme 177: Rh(III)-catalyzed C–H activation reaction.
Scheme 178: Mechanistic cycle.
Scheme 179: Annulation reactions of 2-arylimidazo[1,2-a]pyridines and alkynes.
Scheme 180: Two-way reaction mechanism for annulations reaction.
Scheme 181: [RuCl2(p-cymene)]2-catalyzed C–C bond formation reaction.
Scheme 182: Reported reaction mechanism.
Scheme 183: Fe(III) catalyzed C-3 formylation approach.
Scheme 184: SET mechanism-catalyzed by Fe(III).
Scheme 185: Ni(dpp)Cl2-catalyzed KTC coupling.
Scheme 186: Pd-catalyzed SM coupling.
Scheme 187: Vanadium-catalyzed coupling of IP and NMO.
Scheme 188: Mechanistic cycle.
Scheme 189: Selective C3/C5–H bond functionalizations by mono and bimetallic systems.
Scheme 190: rGO-Ni@Pd-catalyzed C–H bond arylation of imidazo[1,2-a]pyridine.
Scheme 191: Mechanistic pathway for heterogeneously catalyzed arylation reaction.
Scheme 192: Zinc triflate-catalyzed coupling reaction of substituted propargyl alcohols.
Host–guest interactions in nor-seco-cucurbit[10]uril: novel guest-dependent molecular recognition and stereoisomerism
- Xiaodong Zhang,
- Wei Wu,
- Zhu Tao and
- Xin-Long Ni
Beilstein J. Org. Chem. 2019, 15, 1705–1711, doi:10.3762/bjoc.15.166
Graphical Abstract
Scheme 1: Chemical structures of host-1, host-2, G1, and G2.
Figure 1: 1H NMR spectra of G1 (1.0 mmol, D2O, pD = 2.0) in the presence of host-1 at different concentration...
Figure 2: 1H NMR spectra of G1 (1.0 mmol, D2O, pD = 2.0) in the presence of host-2 at different concentration...
Scheme 2: Plausible diastereomers showing the fluorescence response of G2 with host-1.
Figure 3: Fluorescence spectral changes of G2 (10.0 μM) in the presence of host-1 (a) and host-2 (b) at diffe...
Figure 4: 1H NMR spectra of G2 (1.0 mmol, D2O, pD = 2.0) in the presence of different concentrations of host-1...
Synthesis, photophysical and electrochemical properties of pyridine, pyrazine and triazine-based (D–π–)2A fluorescent dyes
- Keiichi Imato,
- Toshiaki Enoki,
- Koji Uenaka and
- Yousuke Ooyama
Beilstein J. Org. Chem. 2019, 15, 1712–1721, doi:10.3762/bjoc.15.167
Graphical Abstract
Figure 1: Chemical structures of the (D–π–)2A fluorescent dyes OUY-2, OUK-2 and OUJ-2.
Scheme 1: Synthesis of OUY-2, OUK-2 and OUJ-2.
Figure 2: (a) Photoabsorption and (b) fluorescence (λex = ca. 400 nm) spectra of OUY-2 in various solvents. (...
Figure 3: Correlation of the Stokes shift (νst) and the orientation polarizability (Δf) according to Equation 1 and Equation 2, r...
Figure 4: Fluorescence spectra of OUY-2 (λex = 370 nm), OUK-2 (λex = 370 nm) and OUJ-2 (λex = 380 nm) in the ...
Figure 5: Cyclic voltammograms of OUY-2, OUK-2 and OUJ-2 in DMF containing 0.1 M Bu4NClO4. The arrow denotes ...
Figure 6: Energy level diagram, HOMO and LUMO of OUY-2, OUK-2 and OUJ-2, derived from the DFT calculations at...
N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds
- Iwona E. Głowacka,
- Aleksandra Trocha,
- Andrzej E. Wróblewski and
- Dorota G. Piotrowska
Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168
Graphical Abstract
Figure 1: Examples of three-carbon chirons.
Figure 2: Structures of derivatives of N-(1-phenylethyl)aziridine-2-carboxylic acid 5–8.
Figure 3: Synthetic equivalency of aziridine aldehydes 6.
Scheme 1: Synthesis of N-(1-phenylethyl)aziridine-2-carboxylates 5. Reagents and conditions: a) TEA, toluene,...
Scheme 2: Absolute configuration at C2 in (2S,1'S)-5a. Reagents and conditions: a) 20% HClO4, 80 °C, 30 h the...
Scheme 3: Major synthetic strategies for a 2-ketoaziridine scaffold [R* = (R)- or (S)-1-phenylethyl; R′ = Alk...
Scheme 4: Synthesis of cyanide (2S,1'S)-13. Reagents and conditions: a) NH3, EtOH/H2O, rt, 72 h; b) Ph3P, CCl4...
Scheme 5: Synthesis of key intermediates (R)-16 and (R)-17 for (R,R)-formoterol (14) and (R)-tamsulosin (15)....
Scheme 6: Synthesis of mitotic kinesin inhibitors (2R/S,1'R)-23. Reagents and conditions: a) H2, Pd(OH)2, EtO...
Scheme 7: Synthesis of (R)-mexiletine ((R)-24). Reagents and conditions: a) TsCl, TEA, DMAP, CH2Cl2, rt, 1 h;...
Scheme 8: Synthesis of (−)-cathinone ((S)-27). Reagents and conditions: a) PhMgBr, ether, 0 °C; b) H2, 10% Pd...
Scheme 9: Synthesis of N-Boc-norpseudoephedrine ((1S,2S)-(+)-29) and N-Boc-norephedrine ((1R,2S)-29). Reagent...
Scheme 10: Synthesis of (−)-ephedrine ((1R,2S)-31). Reagents and conditions: a) TfOMe, MeCN then NaBH3CN, rt; ...
Scheme 11: Synthesis of xestoaminol C ((2S,3R)-35), 3-epi-xestoaminol C ((2S,3S)-35) and N-Boc-spisulosine ((2S...
Scheme 12: Synthesis of ʟ-tryptophanol ((S)-41). Reagents and conditions: a) CDI, MeCN, rt, 1 h then TMSI, MeC...
Scheme 13: Synthesis of ʟ-homophenylalaninol ((S)-42). Reagents and conditions: a) NaH, THF, 0 °C to −78 °C, 1...
Scheme 14: Synthesis of ᴅ-homo(4-octylphenyl)alaninol ((R)-47) and a sphingolipid analogue (R)-48. Reagents an...
Scheme 15: Synthesis of florfenicol ((1R,2S)-49). Reagents and conditions: a) (S)-1-phenylethylamine, TEA, MeO...
Scheme 16: Synthesis of natural tyroscherin ((2S,3R,6E,8R,10R)-55). Reagents and conditions: a) I(CH2)3OTIPS, t...
Scheme 17: Syntheses of (−)-hygrine (S)-61, (−)-hygroline (2S,2'S)-62 and (−)-pseudohygroline (2S,2'R)-62. Rea...
Scheme 18: Synthesis of pyrrolidine (3S,3'R)-68, a fragment of the fluoroquinolone antibiotic PF-00951966. Rea...
Scheme 19: Synthesis of sphingolipid analogues (R)-76. Reagents and conditions: a) BnBr, Mg, THF, reflux, 6 h;...
Scheme 20: Synthesis of ᴅ-threo-PDMP (1R,2R)-81. Reagents and conditions: a) TMSCl, NaI, MeCN, rt, 1 h 50 min,...
Scheme 21: Synthesis of the sphingolipid analogue SG-14 (2S,3S)-84. Reagents and conditions: a) LiAlH4, THF, 0...
Scheme 22: Synthesis of the sphingolipid analogue SG-12 (2S,3R)-88. Reagents and conditions: a) 1-(bromomethyl...
Scheme 23: Synthesis of sphingosine-1-phosphate analogues DS-SG-44 and DS-SG-45 (2S,3R)-89a and (2S,3R)-89a. R...
Scheme 24: Synthesis of N-Boc-safingol ((2S,3S)-95) and N-Boc-ᴅ-erythro-sphinganine ((2S,3R)-95). Reagents and...
Scheme 25: Synthesis of ceramide analogues (2S,3R)-96. Reagents and conditions: a) NaBH4, ZnCl2, MeOH, −78 °C,...
Scheme 26: Synthesis of orthogonally protected serinols, (S)-101 and (R)-102. Reagents and conditions: a) BnBr...
Scheme 27: Synthesis of N-acetyl-3-phenylserinol ((1R,2R)-105). Reagents and conditions: a) AcOH, CH2Cl2, refl...
Scheme 28: Synthesis of (S)-linezolid (S)-107. Reagents and conditions: a) LiAlH4, THF, 0 °C to reflux; b) Boc2...
Scheme 29: Synthesis of (2S,3S,4R)-2-aminooctadecane-1,3,4-triol (ᴅ-ribo-phytosphingosine) (2S,3S,4R)-110. Rea...
Scheme 30: Syntheses of ᴅ-phenylalanine (R)-116. Reagents and conditions: a) AcOH, CH2Cl2, reflux, 4 h; b) MsC...
Scheme 31: Synthesis of N-Boc-ᴅ-3,3-diphenylalanine ((R)-122). Reagents and conditions: a) PhMgBr, THF, −78 °C...
Scheme 32: Synthesis of ethyl N,N’-di-Boc-ʟ-2,3-diaminopropanoate ((S)-125). Reagents and conditions: a) NaN3,...
Scheme 33: Synthesis of the bicyclic amino acid (S)-(+)-127. Reagents and conditions: a) BF3·OEt2, THF, 60 °C,...
Scheme 34: Synthesis of lacosamide, (R)-2-acetamido-N-benzyl-3-methoxypropanamide (R)-130. Reagents and condit...
Scheme 35: Synthesis of N-Boc-norfuranomycin ((2S,2'R)-133). Reagents and conditions: a) H2C=CHCH2I, NaH, THF,...
Scheme 36: Synthesis of MeBmt (2S,3R,4R,6E)-139. Reagents and conditions: a) diisopropyl (S,S)-tartrate (E)-cr...
Scheme 37: Synthesis of (+)-polyoxamic acid (2S,3S,4S)-144. Reagents and conditions: a) AD-mix-α, MeSO2NH2, t-...
Scheme 38: Synthesis of the protected 3-hydroxy-ʟ-glutamic acid (2S,3R)-148. Reagents and conditions: a) LiHMD...
Scheme 39: Synthesis of (+)-isoserine (R)-152. Reagents and conditions: a) AcCl, MeCN, rt, 0.5 h then Na2CO3, ...
Scheme 40: Synthesis of (3R,4S)-N3-Boc-3,4-diaminopentanoic acid (3R,4S)-155. Reagents and conditions: a) Ph3P...
Scheme 41: Synthesis of methyl (2S,3S,4S)-4-(dimethylamino)-2,3-dihydroxy-5-methoxypentanoate (2S,3S,4S)-159. ...
Scheme 42: Syntheses of methyl (3S,4S) 4,5-di-N-Boc-amino-3-hydroxypentanoate ((3S,4S)-164), methyl (3S,4S)-4-N...
Scheme 43: Syntheses of (3R,5S)-5-(aminomethyl)-3-(4-methoxyphenyl)dihydrofuran-2(3H)-one ((3R,5S)-168). Reage...
Scheme 44: Syntheses of a series of imidazolin-2-one dipeptides 175–177 (for R' and R'' see text). Reagents an...
Scheme 45: Syntheses of (2S,3S)-N-Boc-3-hydroxy-2-hydroxymethylpyrrolidine ((2S,3S)-179). Reagents and conditi...
Scheme 46: Syntheses of enantiomers of 1,4-dideoxy-1,4-imino-ʟ- and -ᴅ-lyxitols (2S,3R,4S)-182 and (2R,3S,4R)-...
Scheme 47: Synthesis of 1,4-dideoxy-1,4-imino-ʟ-ribitol (2S,3S,4R)-182. Reagents and conditions: a) AcOH, CH2Cl...
Scheme 48: Syntheses of 1,4-dideoxy-1,4-imino-ᴅ-arabinitol (2R,3R,4R)-182 and 1,4-dideoxy-1,4-imino-ᴅ-xylitol ...
Scheme 49: Syntheses of natural 2,5-imino-2,5,6-trideoxy-ʟ-gulo-heptitol ((2S,3R,4R,5R)-184) and its C4 epimer...
Scheme 50: Syntheses of (−)-dihydropinidine ((2S,6R)-187a) (R = C3H7) and (2S,6R)-isosolenopsins (2S,6R)-187b ...
Scheme 51: Syntheses of (+)-deoxocassine ((2S,3S,6R)-190a, R = C12H25) and (+)-spectaline ((2S,3S,6R)-190b, R ...
Scheme 52: Synthesis of (−)-microgrewiapine A ((2S,3R,6S)-194a) and (+)-microcosamine A ((2S,3R,6S)-194b). Rea...
Scheme 53: Syntheses of ʟ-1-deoxynojirimycin ((2S,3S,4S,5R)-200), ʟ-1-deoxymannojirimycin ((2S,3S,4S,5S)-200) ...
Scheme 54: Syntheses of 1-deoxy-ᴅ-galacto-homonojirimycin (2R,3S,4R,5S)-211. Reagents and conditions: a) MeONH...
Scheme 55: Syntheses of 7a-epi-hyacinthacine A1 (1S,2R,3R,7aS)-220. Reagents and conditions: a) TfOTBDMS, 2,6-...
Scheme 56: Syntheses of 8-deoxyhyacinthacine A1 ((1S,2R,3R,7aR)-221). Reagents and conditions: a) H2, Pd/C, PT...
Scheme 57: Syntheses of (+)-lentiginosine ((1S,2S,8aS)-227). Reagents and conditions: a) (EtO)2P(O)CH2COOEt, L...
Scheme 58: Syntheses of 8-epi-swainsonine (1S,2R,8S,8aR)-231. Reagents and conditions: a) Ph3P=CHCOOMe, MeOH, ...
Scheme 59: Synthesis of a protected vinylpiperidine (2S,3R)-237, a key intermediate in the synthesis of (−)-sw...
Scheme 60: Synthesis of a modified carbapenem 245. Reagents and conditions: a) AcOEt, LiHMDS, THF, −78 °C, 1.5...
Functional panchromatic BODIPY dyes with near-infrared absorption: design, synthesis, characterization and use in dye-sensitized solar cells
- Quentin Huaulmé,
- Cyril Aumaitre,
- Outi Vilhelmiina Kontkanen,
- David Beljonne,
- Alexandra Sutter,
- Gilles Ulrich,
- Renaud Demadrille and
- Nicolas Leclerc
Beilstein J. Org. Chem. 2019, 15, 1758–1768, doi:10.3762/bjoc.15.169
Graphical Abstract
Figure 1: Molecular structures of the two target compounds BOD-TTPA-alk and BOD-TTPA, and the chemical struct...
Figure 2: a) Geometrical optimization of four representative BODIPY-based materials for DSSCs application. b)...
Figure 3: Predicted absorption spectra of the four dyes.
Figure 4: Synthetic scheme of the selected materials. a) hydroxylamine hydrochloride, NaHCO3, DMSO, 60 °C the...
Figure 5: a) Absorption spectra of compounds BOD-TTPA-alk and BOD-TTPA (THF, ≈10−6 M, 25 °C). b) Absorbance s...
Figure 6: J(V) curves of the best performing DSSCs devices sensitized with compounds BOD-TTPA-alk (blue trace...
Figure 7: Photovoltaic parameters evolution with the increasing concentration of tBP in the electrolyte.
The cyclopropylcarbinyl route to γ-silyl carbocations
- Xavier Creary
Beilstein J. Org. Chem. 2019, 15, 1769–1780, doi:10.3762/bjoc.15.170
Graphical Abstract
Scheme 1: Solvolyses of cyclopropylcarbinyl and cyclobutyl substrates.
Scheme 2: The cyclopropylcarbinyl–cyclobutyl–homoallyl cation manifold.
Figure 1: Electron-deficient carbocations.
Scheme 3: Solvolyses of γ-trimethylsilylcyclobutyl substrates.
Figure 2: Substrates of interest.
Scheme 4: Synthesis of mesylates 19 and 20.
Scheme 5: Reaction of mesylate 19 in CD3CO2D.
Scheme 6: Reaction of mesylate 20 in CD3CO2D.
Figure 3: M062X/6-311+G** calculated structures and relative energies of cations 24, 27, and transition state ...
Scheme 7: Synthesis of mesylates 31 and 32.
Scheme 8: Reaction of mesylate 31 in CD3CO2D.
Scheme 9: Reaction of mesylate 32 in CD3CO2D.
Scheme 10: Reaction of trifluoroacetate 48 in CD3CO2D.
Scheme 11: Bicyclobutane formation from a γ-trimethylsilyl cation.
Scheme 12: Formation of triflates 60 and 61.
Scheme 13: Formation of triflates 67, 68, and 69.
Scheme 14: Reactions of substrates with electron-withdrawing groups in CD3CO2D.
Figure 4: γ-Trimethylsilyl cations.
Scheme 15: Bicyclobutane formation from mesylate 76 in CH3CO2H.
Scheme 16: Reactions of triflates 60 and 67 in CD3CO2D.
A golden opportunity: benzofuranone modifications of aurones and their influence on optical properties, toxicity, and potential as dyes
- Joza Schmitt and
- Scott T. Handy
Beilstein J. Org. Chem. 2019, 15, 1781–1785, doi:10.3762/bjoc.15.171
Graphical Abstract
Figure 1: Aurone ring system and numbering.
Figure 2: Aurone syntheses.
Figure 3: UV–vis spectral comparisons in acetonitrile.
Figure 4: Fabric dying and photobleaching. The top two sets show dyed fabric strips with premordant, simultan...
Metal-free mechanochemical oxidations in Ertalyte® jars
- Andrea Porcheddu,
- Francesco Delogu,
- Lidia De Luca,
- Claudia Fattuoni and
- Evelina Colacino
Beilstein J. Org. Chem. 2019, 15, 1786–1794, doi:10.3762/bjoc.15.172
Graphical Abstract
Scheme 1: Oxidation of 3-pheny-1-propanol (1a) with N-chlorosuccinimide (NCS) in the presence of (2,2,6,6-tet...
Scheme 2: Hypothesized pathways for the TEMPO-assisted oxidation of alcohols in a) basic or b) acidic reactio...
Scheme 3: TEMPO-assisted oxidation of 3-pheny-1-propanol (1a) under mechanical activation conditions. aPercen...
Scheme 4: Scope of primary alcohol oxidation under mechanical activation conditions. aAll yields refer to iso...
Scheme 5: Proposed mechanism for the oxidation of benzylic alcohols 6a and 7a under mechanochemical condition...
Scheme 6: Scope of secondary alcohols in the oxidation under mechanical activation conditions. aAll yields re...
Scheme 7: Possible mechanism for the TEMPO-mediated oxidation of primary and secondary alcohols by using NaOC...
Complexation of 2,6-helic[6]arene and its derivatives with 1,1′-dimethyl-4,4′-bipyridinium salts and protonated 4,4'-bipyridinium salts: an acid–base controllable complexation
- Jing Li,
- Qiang Shi,
- Ying Han and
- Chuan-Feng Chen
Beilstein J. Org. Chem. 2019, 15, 1795–1804, doi:10.3762/bjoc.15.173
Graphical Abstract
Figure 1: Structures and proton designations of hosts H1–5 and guests G1–4.
Scheme 1: Synthesis of hosts H3–5.
Figure 2: Partial 1H NMR spectra (400 MHz CDCl3/acetone-d6 1:2 (v/v), 298 K) of (a) free H1, (b) H1 with 1.0 ...
Figure 3: Partial 1H NMR spectra (400 MHz, CD2Cl2, 298 K) of (a) free H1, (b) H1 with 1.0 equiv G4, (c) free ...
Figure 4: Crystal structure of complex H1·G1. (a) Top view, (b) side view, and (c) packing viewed along c-axi...
Figure 5: Crystal structure of complex H5·G1. (a) Top view, (b) side view, and (c) packing viewed along the a-...
Figure 6: Calculated structures of the complexes at the B3LYP/6-31G level of theory. (a) Top view and (b) sid...
Figure 7: Schematic representation of the acid–base controlled complexation process and partial 1H NMR spectr...
