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Search for "cross-polarization" in Full Text gives 8 result(s) in Beilstein Journal of Organic Chemistry.
Selective formation of a zwitterion adduct and bicarbonate salt in the efficient CO2 fixation by N-benzyl cyclic guanidine under dry and wet conditions
- Yoshiaki Yoshida,
- Naoto Aoyagi and
- Takeshi Endo
Beilstein J. Org. Chem. 2018, 14, 2204–2211, doi:10.3762/bjoc.14.194
- ) mode. FTIR spectra were recorded on a Thermo Scientific Nicolet iS10 spectrometer equipped with a Smart iTR diamond ATR sampling accessory in the range of 4000–650 cm−1. Solid-state NMR, 13C cross-polarization (CP)/magic angle spinning (MAS, 99.5 MHz) measurements were performed on a JEOL JNM-ECX 400
Graphical Abstract
Scheme 1: Fixation of CO2 (200 mL/min) by 1 under (a) dry and (b) wet conditions.
Figure 1: Zwitterion adduct 2 and bicarbonate salt 3 confirmed by elemental analysis.
Figure 2: 13C NMR spectra of (a) 1 observed in DMSO-d6, (b) 3' prepared with 2 and D2O observed in D2O, and (...
Figure 3: FTIR-ATR spectra of zwitterion adduct 2 and bicarbonate salt 3 expanded at the range of 1500–1800 cm...
Figure 4: 13C-CPMAS NMR spectra of zwitterion adduct 2 and bicarbonate salt 3 expanded at the range of 30–170...
Figure 5: The optimized geometries of zwitterion adduct 2 and bicarbonate salt 3 estimated by DFT calculation...
Figure 6: TGA trace of (a) zwitterion adduct 2 and (b) bicarbonate salt 3 observed under N2 flow (200 mL/min)...
Scheme 2: Proposal decomposition paths and theoretical weight loss values of (a) zwitterion adduct 2 and (b) ...
Dynamics and interactions of ibuprofen in cyclodextrin nanosponges by solid-state NMR spectroscopy
- Monica Ferro,
- Franca Castiglione,
- Nadia Pastori,
- Carlo Punta,
- Lucio Melone,
- Walter Panzeri,
- Barbara Rossi,
- Francesco Trotta and
- Andrea Mele
Beilstein J. Org. Chem. 2017, 13, 182–194, doi:10.3762/bjoc.13.21
- indicated that the structure of the nanosponge did not undergo changes upon drug loading compared to the unloaded system. However, the 13C NMR spectra collected under variable contact time cross-polarization (VCT-CP) conditions showed that the polymeric scaffold CDNS changed significantly its dynamic regime
- reported matched the information from powder X-ray diffraction profiles. Keywords: cross-polarization; cyclodextrin; ibuprofen; nanosponges; solid-state NMR; Introduction In the last ten years cyclodextrin nanosponges (CDNS) polymer materials received great attention as promising new materials in several
- the polymer network in the solid state. The methodological approach here presented relies upon two different solid state NMR methodologies and it is finally supported by powder X-ray diffraction (PXRD) data. In particular, here we present the use of variable contact time (VCT) cross-polarization 13C
Graphical Abstract
Figure 1: Schematic thermodynamic description of the CP process and time constants. The I-S model (left), the ...
Figure 2: 1H MAS NMR spectra of a) CDNS(1:8)-IbuNa and b) CDNS(1:8). The inset (top right) shows the expansio...
Figure 3: The effect of the spinning speed on the spectral features. 1H MAS NMR spectra of a) CDNS(1:4)-IbuNa...
Figure 4: 13C CP-MAS NMR spectra for samples of β-CD (top), CDNS(1:4) (middle) and CDNS(1:8) polymers (bottom...
Figure 5: 13C CP-MAS NMR spectrum of: a) CDNS(1:4) polymer; b) CDNS(1:4)-IbuNa system; c) CDNS(1:8)-IbuNa sys...
Figure 6: 13C CP-MAS NMR spectra of CDNS(1:4) acquired with CP variable contact time in the range 50 μs–7 ms.
Figure 7: Time dependence of 13C magnetization for CDNS(1:4) (left) and CDNS(1:8) (right) polymers.
Figure 8: 1H-13C CP oscillatory kinetics for the carbon C(1) and C(4) of CDNS(1:4)-IbuNa sample (left) and CD...
Figure 9: 1H-13C CP oscillatory kinetics for the ibuprofen aromatic carbon atoms C(6,8) in samples CDNS(1:4)-...
Figure 10: PXRD patterns of: a) CDNS(1:8), b) CDNS(1:4), c) CDNS(1:8)-IbuNa loaded, d) CDNS(1:4)-IbuNa loaded,...
Cross-linked cyclodextrin-based material for treatment of metals and organic substances present in industrial discharge waters
- Élise Euvrard,
- Nadia Morin-Crini,
- Coline Druart,
- Justine Bugnet,
- Bernard Martel,
- Cesare Cosentino,
- Virginie Moutarlier and
- Grégorio Crini
Beilstein J. Org. Chem. 2016, 12, 1826–1838, doi:10.3762/bjoc.12.172
- polymers. These diffractograms indicate a wide amorphous peak between values of 2θ of 10 and 30°, highlighting that polymers are amorphous. No significant differences were observed between the two types of polymer. Solid-state 13C NMR spectra of the polymer are presented in Figure 4. The cross polarization
- C-6’, C-6 and C-7, respectively. These attributions were confirmed using cross-polarization with a polarization inversion sequence (CPPI spectrum not shown), which revealed three CH2 signals due to the CD and also a peak at 30.15 ppm corresponding to CH2 groups introduced by the cross-linking agent
- such as cross polarization magic angle spinning (CP MAS) and MAS. The spectra were recorded with a Bruker spectrometer operating at 75.47 MHz and 303 K. The compounds were placed in a zirconium rotor, 4 mm in diameter and 21 mm high. The chemical shifts were recorded relative to tetramethylsilane with
Graphical Abstract
Figure 1: Chemical structure of the non-activated polyBTCA-CD.
Figure 2: Determination of the PZC for the non-activated and activated polyBTCA-CD polymers (pHi: initial pH ...
Figure 3: XRD pattern of the two polymers: non-activated and activated polyBTCA-CD.
Figure 4: CPMAS and MAS spectra of polyBTCA-CD.
Figure 5: Adsorption capacity (%) of (a) the non-activated and (b) the activated (NaHCO3 treatment) polyBTCA-...
Figure 6: Adsorption kinetics for two solutions containing five metals at two concentrations (solution at 10 ...
Figure 7: Removal efficiency (%) after treatment with activated polyBTCA-CD (concentration = 2 g·L−1) for (a)...
Figure 8: Removal efficiency (%) of inorganic elements after treatment of five DWs by polyBTCA-CD (concentrat...
Polydisperse methyl β-cyclodextrin–epichlorohydrin polymers: variable contact time 13C CP-MAS solid-state NMR characterization
- Isabelle Mallard,
- Davy Baudelet,
- Franca Castiglione,
- Monica Ferro,
- Walter Panzeri,
- Enzio Ragg and
- Andrea Mele
Beilstein J. Org. Chem. 2015, 11, 2785–2794, doi:10.3762/bjoc.11.299
- obtained and characterized by solid-state 13C NMR spectroscopy under cross-polarization magic angle spinning (CP-MAS) conditions. The polymers were prepared by using the same synthetic conditions but with different molar ratios of imprinting agent/monomer, leading to morphologically equivalent materials
- but with different absorption properties. The main purpose of the work was to find a suitable spectroscopic descriptor accounting for the different imprinting process in three homogeneous polymeric networks. The polymers were characterized by studying the kinetics of the cross-polarization process
- confirmed that the three polymers are morphologically similar. Thus the combined use of TCH and T1ρ can be helpful for the characterization and fine tuning of imprinted polymeric matrices. Keywords: dynamic cross-polarization; epichlorohydrin; imprinted; insoluble CRYSMEB polymers; solid-state NMR
Graphical Abstract
Scheme 1: Schematic representation of molecular imprinting technique. i) Polymerization process with toluene-...
Figure 1: FTIR spectra of (A): native CRYSMEB, (B): D3 (toluene/CD 3:1), (C): D2 (toluene/CD 4:1), and (D): D...
Figure 2: Top: XRPD pattern for CRYSMEB. Bottom: XRPD pattern for D1 polymer. The diffraction peaks denoted w...
Figure 3: 13C {1H} CP-MAS spectra of polymers D1, D2 and D3. Peak assignment is given in the upper trace.
Figure 4: 13C {1H} CP-MAS spectra of native CRYSMEB and polymer D3. Peak assignment is given on CRYSMEB spect...
Figure 5: 1D 13C CP/MAS spectra of polymer D3 as a function of the contact time varying from 35 μs to 4 ms.
Figure 6: Cross-polymerization (CP) build-up curve of the 13C resonances with variable contact times for the ...
Figure 7: Cross-polymerization (CP) build-up curve of the 13C resonances with variable contact time for polym...
Figure 8: CP build-up curves of the 13C resonances with cross-polymerization in the range 0–100 μs for polyme...
Loose-fit polypseudorotaxanes constructed from γ-CDs and PHEMA-PPG-PEG-PPG-PHEMA
- Tao Kong,
- Lin Ye,
- Ai-ying Zhang and
- Zeng-guo Feng
Beilstein J. Org. Chem. 2014, 10, 2461–2469, doi:10.3762/bjoc.10.257
- and tetramethylsilane (TMS) as an internal standard. 13C cross-polarization magic-angle spinning (CP/MAS) NMR spectra were measured on a Bruker AV 300 NMR spectrometer with a single contact time of 1 ms and a spinning rate of 5 kHz. Chemical shifts were compared to an external adamantane standard. Gel
Graphical Abstract
Scheme 1: Schematic description of self-assembly of γ-CDs with BrPPO-PEO-PPOBr and PHEMA-PPO-PEO-PPO-PHEMA in...
Scheme 2: Synthetic pathway of a pentablock copolymer.
Figure 1: Photographs of the turbidity evolution in PEP18CD (1) and PEP26MnCDs (2) (PEP26M9CD (left), PEP26H1...
Figure 2: WXRD spectra of γ-CD, PHEMA, PEP26M, PEP18CD and PEP26MnCDs.
Figure 3: 1H NMR spectra of PEP26M9CD (A), PEP26M18CD (B) and PEP26M27CD (C).
Figure 4: DSC curves of PHEMA, PEP26M, PEP26MnCDs, BrPEPBr and PEP18CD.
Figure 5: TGA curves of γ-CD, PEP26M, PEP26MnCDs, BrPEPBr and PEP18CD.
Figure 6: FTIR spectra of γ-CD, PEP26M, PEP18CD and PEP26MnCDs.
Figure 7: 13C CP/MAS NMR spectra of PEP26M, γ-CD and PEP26M27CD.
An experimental and theoretical NMR study of NH-benzimidazoles in solution and in the solid state: proton transfer and tautomerism
- Carla I. Nieto,
- Pilar Cabildo,
- M. Ángeles García,
- Rosa M. Claramunt,
- Ibon Alkorta and
- José Elguero
Beilstein J. Org. Chem. 2014, 10, 1620–1629, doi:10.3762/bjoc.10.168
- (Non-Quaternary Suppression) experiment by conventional cross-polarization was recorded; before the acquisition the decoupler is switched off for a very short time of 25 μs [38][39][40]. For 15N CPMAS were: spectral width, 40 kHz; recycle delay, 5–60 s; acquisition time, 35 ms; contact time, 7–9 ms
Graphical Abstract
Figure 1: The five studied compounds.
Figure 2: Trimers A (left) and B (right) of 1.
Figure 3: The tautomerism of 1H-benzimidazole.
Figure 4: The 13C CPMAS NMR spectrum of 3.
Figure 5: The two independent molecules of 3 drawn with the Mercury program [26].
Figure 6: The evolution of the spectrum of 1 with temperature in HMPA-d18.
Structure of 1,5-benzodiazepinones in the solid state and in solution: Effect of the fluorination in the six-membered ring
- Marta Pérez-Torralba,
- Rosa M. Claramunt,
- M. Ángeles García,
- Concepción López,
- M. Carmen Torralba,
- M. Rosario Torres,
- Ibon Alkorta and
- José Elguero
Beilstein J. Org. Chem. 2013, 9, 2156–2167, doi:10.3762/bjoc.9.253
- protonated and unprotonated carbon atoms, the NQS (non-quaternary suppression) experiment by conventional cross-polarization was recorded; before the acquisition the decoupler is switched off for a very short time of 25 μs [40][41][42]. And for 15N CPMAS were: spectral width, 40 kHz; recycle delay, 5 s
Graphical Abstract
Figure 1: The six 1,5-benzodiazepinones discussed in this paper together with clobazam.
Scheme 1: Synthesis of compounds 1 and 2.
Figure 2: The X-ray structures of 3a (TUPSAZ), 5a (EFARUA). In TUPSAZ there is a disordered water molecule.
Figure 3: ORTEP plot (30% probability) of 1, showing the X-ray labeling of the asymmetric unit.
Figure 4: View of the zigzag chain formed in 1, showing the H-bond and F–F interactions.
Figure 5: ORTEP plot (20% probability) of 2, showing the X-ray labeling of the asymmetric unit.
Figure 6: Packing of 2 showing the F–F contacts along the chain (orange) and the π–π interactions that form t...
Figure 7: The different tautomers in the 1H and 1-methyl series.
Figure 8: 2-Methoxy-4-methyl-3H-1,5-benzodiazepine (7).
Figure 9: 1H–19F coupling constant values either through-bond or through-space.
Figure 10: The optimized geometry of the TS of 2a inversion.
Figure 11: Equations used to transform absolute shieldings into chemical shifts [38,39].
The chemistry of bisallenes
- Henning Hopf and
- Georgios Markopoulos
Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225
Graphical Abstract
Figure 1: Loschmidt’s structure proposal for benzene (1) (Scheme 181 from [3]) and the corresponding modern stru...
Figure 2: The first isolated bisallenes.
Figure 3: Carbon skeletons of selected bisallenes discussed in this review.
Scheme 1: The preparation of 1,2,4,5-hexatetraene (2).
Scheme 2: The preparation of a conjugated bisallene by the DMS-protocol.
Scheme 3: Preparation of the 3-deuterio- and 3,4-dideuterio derivatives of 24.
Scheme 4: A versatile method to prepare alkylated conjugated bisallenes and other allenes.
Scheme 5: A preparation of 3,4-dimethyl-1,2,4,5-hexatetraene (38).
Scheme 6: A (C6 + 0)-approach to 1,2,4,5-hexatetraene (2).
Scheme 7: The preparation of a fully alkylated bisallenes from a 2,4-hexadiyne-1,6-diol diacetate.
Scheme 8: The preparation of the first phenyl-substituted conjugated bisallenes 3 and 4.
Scheme 9: Selective hydrogenation of [5]cumulenes to conjugated bisallenes: another (C6 + 0)-route.
Scheme 10: Aryl-substituted conjugated bisallenes by a (C3 + C3)-approach.
Scheme 11: Hexaphenyl-1,2,4,5-hexatetraene (59) by a (C3 + C3)-approach.
Scheme 12: An allenation route to conjugated bisallenes.
Scheme 13: The preparation of 3,4-difunctionalized conjugated bisallenes.
Scheme 14: Problems during the preparation of sulfur-substituted conjugated bisallenes.
Scheme 15: The preparation of 3,4-dibromo bisallenes.
Scheme 16: Generation of allenolates by an oxy-Cope rearrangement.
Scheme 17: A linear trimerization of alkynes to conjugated bisallenes: a (C2 + C2 + C2)-protocol.
Scheme 18: Preparation of a TMS-substituted conjugated bisallene by a C3-dimerization route.
Scheme 19: A bis(trimethylsilyl)bisallene by a C3-coupling protocol.
Scheme 20: The rearrangement of highly substituted benzene derivatives into their conjugated bisallenic isomer...
Scheme 21: From fully substituted benzene derivatives to fully substituted bisallenes.
Scheme 22: From a bicyclopropenyl to a conjugated bisallene derivative.
Scheme 23: The conversion of a bismethylenecyclobutene into a conjugated bisallene.
Scheme 24: The preparation of monofunctionalized bisallenes.
Scheme 25: Preparation of bisallene diols and their cyclization to dihydrofurans.
Scheme 26: A 3,4-difunctionalized conjugated bisallene by a C3-coupling process.
Scheme 27: Preparation of a bisallenic diketone by a coupling reaction.
Scheme 28: Sulfur and selenium-substituted bisallenes by a [2.3]sigmatropic rearrangement.
Scheme 29: The biallenylation of azetidinones.
Scheme 30: The preparation of a fully ferrocenylated conjugated bisallene.
Scheme 31: The first isomerization of a 1,5-hexadiyne to a 1,2,4,5-hexatetraene.
Scheme 32: The preparation of alkynyl-substituted bisallenes by a C3-dimerization protocol.
Scheme 33: Preparation of another completely ferrocenylated bisallene.
Scheme 34: The cyclization of 1,5-hexadiyne (129) to 3,4-bismethylenecyclobutene (130) via 1,2,4,5-hexatetraen...
Scheme 35: Stereochemistry of the thermal cyclization of bisallenes to bismethylenecyclobutenes.
Scheme 36: Bisallene→bismethylenecyclobutene ring closures in the solid state.
Scheme 37: A bisallene cyclization/dimerization reaction.
Scheme 38: A selection of Diels–Alder additions of 1,2,4,5-hexatetraene with various double-bond dienophiles.
Scheme 39: The stereochemistry of the [2 + 4] cycloaddition to conjugated bisallenes.
Scheme 40: Preparation of azetidinone derivatives from conjugated bisallenes.
Scheme 41: Cycloaddition of heterodienophiles to a conjugated bisallene.
Scheme 42: Addition of triple-bond dienophiles to conjugated bisallenes.
Scheme 43: Sulfur dioxide addition to conjugated bisallenes.
Scheme 44: The addition of a germylene to a conjugated bisallene.
Scheme 45: Trapping of conjugated bisallenes with phosphinidenes.
Scheme 46: The cyclopropanantion of 1,2,4,5-hexatetraene (2).
Scheme 47: Photochemical reactions involving conjugated bisallenes.
Scheme 48: Base-catalyzed isomerizations of conjugated bisallenes.
Scheme 49: Ionic additions to a conjugated bisallene.
Scheme 50: Oxidation reactions of a conjugated bisallene.
Scheme 51: The mechanism of oxidation of the bisallene 24.
Scheme 52: CuCl-catalyzed cyclization of 1,2,4,5-hexatetraene (2).
Scheme 53: The conversion of conjugated bisallenes into cyclopentenones.
Scheme 54: Oligomerization of a conjugated bisallene by nickel catalysts.
Scheme 55: Generation of 1,2,5,6-heptatetraene (229) as a reaction intermediate.
Scheme 56: The preparation of a stable derivative of 1,2,5,6-heptatetraene.
Scheme 57: A bisallene with a carbonyl group as a spacer element.
Scheme 58: The first preparation of 1,2,6,7-octatetraene (242).
Scheme 59: Preparation of 1,2,6,7-octatetraenes by (C4 + C4)-coupling of enynes.
Scheme 60: Preparation of 1,2,6,7-octatetraenes by (C4 + C4)-coupling of homoallenyl bromides.
Scheme 61: Preparation of 1,2,6,7-octatetraenes by alkylation of propargylic substrates.
Scheme 62: Preparation of two highly functionalized 1,2,6,7-octatetraenes.
Scheme 63: Preparation of several higher α,ω-bisallenes.
Scheme 64: Preparation of different alkyl derivatives of α,ω-bisallenes.
Scheme 65: The preparation of functionalized 1,2,7,8-nonatetraene derivatives.
Scheme 66: Preparation of functionalized α,ω-bisallenes.
Scheme 67: The preparation of an α,ω-bisallene by direct homologation of an α,ω-bisalkyne.
Scheme 68: The gas-phase pyrolysis of 4,4-dimethyl-1,2,5,6-heptatetraene (237).
Scheme 69: Gas-phase pyrolysis of 1,2,6,7-octatetraene (242).
Scheme 70: The cyclopropanation of 1,2,6,7-octatetraene (242).
Scheme 71: Intramolecular cyclization of 1,2,6,7-octatetraene derivatives.
Scheme 72: The gas-phase pyrolysis of 1,2,7,8-nonatetraene (265) and 1,2,8,9-decatetraene (266).
Scheme 73: Rh-catalyzed cyclization of a functionalized 1,2,7,8-nonatetraene.
Scheme 74: A triple cyclization involving two different allenic substrates.
Scheme 75: Bicyclization of keto derivatives of 1,2,7,8-nonatetraene.
Scheme 76: The preparation of complex organic compounds from functionalized bisallenes.
Scheme 77: Cycloisomerization of an α,ω-bisallene containing a C9 tether.
Scheme 78: Organoborane polymers from α,ω-bisallenes.
Scheme 79: Preparation of trans- (337) and cis-1,2,4,6,7-octapentaene (341).
Scheme 80: The preparation of 4-methylene-1,2,5,6-heptatetraene (349).
Scheme 81: The preparation of acetylenic bisallenes.
Scheme 82: The preparation of derivatives of hydrocarbon 351.
Scheme 83: The construction of macrocyclic alleno-acetylenes.
Scheme 84: Preparation and reactions of 4,5-bismethylene-1,2,6,7-octatetraene (365).
Scheme 85: Preparation of 1,2-bis(propadienyl)benzene (370).
Scheme 86: The preparation of 1,4-bis(propadienyl)benzene (376).
Scheme 87: The preparation of aromatic and heteroaromatic bisallenes by metal-mediated coupling reactions.
Scheme 88: Double cyclization of an aromatic bisallene.
Scheme 89: Preparation of an allenic [15]paracyclophane by a ring-closing metathesis reaction of an aromatic α...
Scheme 90: Preparation of a macrocyclic ring system containing 1,4-bis(propadienyl)benzene units.
Scheme 91: Preparation of copolymers from 1,4-bis(propadienyl)benzene (376).
Scheme 92: A boration/copolymerization sequence of an aromatic bisallene and an aromatic bisacetylene.
Scheme 93: Formation of a layered aromatic bisallene.
Figure 4: The first members of the semicyclic bisallene series.
Scheme 94: Preparation of the first bis(vinylidene)cyclobutane derivative.
Scheme 95: Dimerization of strain-activated cumulenes to bis(vinylidene)cyclobutanes.
Scheme 96: Photodimerization of two fully substituted butatrienes in the solid state.
Scheme 97: Preparation of the two parent bis(vinylidene)cyclobutanes.
Scheme 98: The preparation of 1,3-bis(vinylidene)cyclopentane and its thermal isomerization.
Scheme 99: The preparation of the isomeric bis(vinylidene)cyclohexanes.
Scheme 100: Bi- and tricyclic conjugated bisallenes.
Scheme 101: A selection of polycyclic bisallenes.
Scheme 102: The first endocyclic bisallenes.
Figure 5: The stereochemistry of 1,2,6,7-cyclodecatetraene.
Scheme 103: The preparation of several endocyclic bisallenes.
Scheme 104: Synthesis of diastereomeric derivatives of 1,2,6,7-cyclodecatetraene.
Scheme 105: Preparation of a derivative of 1,2,8,9-cyclotetradecatetraene.
Scheme 106: The preparation of keto derivatives of cyclic bisallenes.
Scheme 107: The preparation of cyclic biscumulenic ring systems.
Scheme 108: Cyclic bisallenes in natural- and non-natural-product chemistry.
Scheme 109: The preparation of iron carbonyl complexes from cyclic bisallenes.
Figure 6: A selection of unknown exocyclic bisallenes that should have interesting chemical properties.
Scheme 110: The thermal isomerization of 1,2-diethynylcyclopropanes and -cyclobutanes.
Scheme 111: Intermediate generation of a cyclooctapentaene.
Scheme 112: Attempted preparation of a cyclodecahexaene.
Scheme 113: The thermal isomerization of 1,5,9-cyclododecatriyne (511) into [6]radialene (514).
Scheme 114: An isomerization involving a diketone derived from a conjugated bisallene.
Scheme 115: Typical reaction modes of heteroorganic bisallenes.
Scheme 116: Generation and thermal behavior of acyclic hetero-organic bisallenes.
Scheme 117: Generation of bis(propadienyl)thioether.
Scheme 118: The preparation of a bisallenic sulfone and its thermal isomerization.
Scheme 119: Bromination of the bisallenic sulfone 535.
Scheme 120: Metalation/hydrolysis of the bisallenic sulfone 535.
Scheme 121: Aromatic compounds from hetero bisallenes.
Scheme 122: Isomerization/cyclization of bispropargylic ethers.
Scheme 123: The preparation of novel aromatic systems by base-catalyzed isomerization of bispropargyl ethers.
Scheme 124: The isomerization of bisacetylenic thioethers to bicyclic thiophenes.
Scheme 125: Aromatization of macrocyclic bispropargylic sulfides.
Scheme 126: Preparation of ansa-compounds from macrocyclic bispropargyl thioethers.
Scheme 127: Alternate route for cyclization of a heterorganic bisallene.
Scheme 128: Multiple isomerization/cyclization of “double” bispropargylic thioethers.
Scheme 129: Preparation of a bisallenyl disulfide and its subsequent bicyclization.
Scheme 130: Thermal cyclization of a bisallenyl thiosulfonate.
Scheme 131: Some reactions of heteroorganic bisallenes with two sulfur atoms.
Scheme 132: Further methods for the preparation of heteroorganic bisallenes.
Scheme 133: Cyclization reactions of heteroorganic bisallenes.
Scheme 134: Thermal cycloadditions of bisallenic tertiary amines.
Scheme 135: Cyclization of a bisallenic tertiary amine in the presence of a transition-metal catalyst.
Scheme 136: A Pauson–Khand reaction of a bisallenic ether.
Scheme 137: Formation of a 2:1adduct from two allenic substrates.
Scheme 138: A ring-forming silastannylation of a bisallenic tertiary amine.
Scheme 139: A three-component cyclization involving a heterorganic bisallene.
Scheme 140: Atom-economic construction of a complex organic framework from a heterorganic α,ω-bisallene.
