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Search for "stereochemical analysis" in Full Text gives 7 result(s) in Beilstein Journal of Organic Chemistry.
Synthesis and stereochemical analysis of dynamic planar chiral oxa[7]orthocyclophene
- Yukiho Hashimoto,
- Yuuya Kawasaki,
- Kazunobu Igawa and
- Katsuhiko Tomooka
Beilstein J. Org. Chem. 2026, 22, 436–442, doi:10.3762/bjoc.22.30
- oxacyclophene enabled the efficient and divergent synthesis of C6-substituted derivatives. The stereochemical analysis of the oxacyclophenes revealed that the iodo- and methyl-substituted derivatives have reasonable stereochemical stability. The planar chirality of the methyl-substituted oxacyclophene was
- successfully transformed into central chirality by epoxidation without loss of enantiomeric purity. Keywords: dynamic chirality; medium-sized heterocycle; orthocyclophene; planar chirality; stereochemical analysis; Introduction In the course of our study on planar chiral medium-sized cyclic molecules [1][2
- ideal alkene plane. Stereochemical analysis of C6-substituted oxacyclophenes Next, HPLC analyses using a chiral stationary phase (chiral column) of the C6-substituted oxacyclophenes were conducted. The baseline separations of the enantiomers of 1ab and 1ad were achieved by using CHIRALCEL OJ-H as the
Graphical Abstract
Figure 1: Stereochemical stability of hetera[7]orthocyclophenes. aHalf-lives of optical activity at 25 °C in ...
Figure 2: Synthetic plan of 1ab and 1ac from 1ad.
Scheme 1: Retrosynthesis of oxacyclophene 1ad.
Scheme 2: Synthesis of C6-iodo-substituted oxacyclophene 1ad.
Scheme 3: Synthesis of derivatives 1ab and 1ac, and ORTEP drawing of 1ac (ellipsoid set at 50% probability le...
Figure 3: Chromatograms of HPLC analysis of compounds 1ab and 1ad using an OJ-H column at 25 °C (OJ-H column,...
Figure 4: Chromatograms of HPLC analysis of 1ac (IE column, 4.6 mm × 250 mm, eluent: hexane/iPrOH 95:5, flow ...
Figure 5: Plausible phenyl-substituent effect on the stereochemical stability of 1ac.
Figure 6: Kinetic measurements for the racemization of 1ab and 1ad.
Figure 7: HPLC analysis of 1ab and 1ad using a CD detector at 5 °C (OJ-H column, 4.6 mm × 250 mm, eluent: hex...
Scheme 4: Epoxidation of (S)-1ab.
A m-quaterphenyl probe for absolute configurational assignments of primary and secondary amines
- Yuka Takeuchi,
- Mutsumi Kobayashi,
- Yuuka Gotoh,
- Mari Ikeda,
- Yoichi Habata,
- Tomohiko Shirai and
- Shunsuke Kuwahara
Beilstein J. Org. Chem. 2025, 21, 2211–2219, doi:10.3762/bjoc.21.168
- ]. However, its use in the analysis of chiral amines has been restricted, largely due to the complexity arising from their conformational flexibility [3]. Circular dichroism (CD) spectroscopy offers a highly sensitive technique for stereochemical analysis at the microgram scale [4][5][6]. In particular
Graphical Abstract
Scheme 1: Coupling reaction of 1 and chiral primary and secondary amines. The central biphenyl moiety rotates...
Figure 1: CD and UV spectra of (a) tertiary amines (S)-2a–e and (b) quaternary ammonium salts (S)-2f,g and (R...
Figure 2: Schematic representation of the preferred conformation of (S)-2a.
Figure 3: Four major conformers of (S)-3a based on B3LYP/6-31G* level.
Figure 4: Four major conformers of (S)-3f based on B3LYP/6-31G* level.
Figure 5: The distribution of conformers of (S)-3a–h against dihedral angles ϕ (C6–C1–C1'–C6') calculated by ...
Figure 6: Crystal structure of (S)-2b. Four conformers exist in the unit cell. Hydrogen atoms are omitted for...
Figure 7: The relationship between the ACD values and excess of P conformer. Excess of P conformer (%) = ([P]...
Menthyl esterification allows chiral resolution for the synthesis of artificial glutamate analogs
- Kenji Morokuma,
- Shuntaro Tsukamoto,
- Kyosuke Mori,
- Kei Miyako,
- Ryuichi Sakai,
- Raku Irie and
- Masato Oikawa
Beilstein J. Org. Chem. 2021, 17, 540–550, doi:10.3762/bjoc.17.48
- observed for 10*, 10, 21*, and 21. Supporting Information File 18: Stereochemical analysis of TKM-38 by the PGME amide method, as a support for the original determination of the configuration of menthyl esters 21 and 21* based on NOESY spectra and CONFLEX calculations. Funding This work was supported by
Graphical Abstract
Figure 1: Artificial glutamate analogs synthesized in an enantiomerically pure form.
Scheme 1: Our established synthetic route to racemic MC-27 ((rac)-4) [5-7].
Scheme 2: Resolution of the MC-27 precursor (rac)-7 by a chiral auxiliary.
Figure 2: Chiral chromatography profiles for the separation of menthyl ester diastereomers 9 and 9*. Conditio...
Scheme 3: Final elaboration of (2R)-MC-27 (4).
Figure 3: Superimposed structures of the top 3 stable conformers (76.5% total population) generated by CONFLE...
Figure 4: Crystallographic analysis of the menthyl ester 10, unequivocally showing the 2R configuration (CCDC...
Scheme 4: Synthesis of (2S)-MC-27 (4*) from 9*.
Scheme 5: Construction and chiral resolution of the 5/5/8-ring system towards the TKM-38 enantiomers.
Figure 5: Structure of Zhan catalyst-1B (14) [14].
Figure 6: Chiral HPLC profiles for the separation of menthyl ester diastereomers 20* and 20. Conditions: 4.6 ...
Scheme 6: Final elaboration towards (2R)- and (2S)-TKM-38.
Figure 7: Superimposed structures of the top 5 stable conformers (89.9% total population) generated by CONFLE...
Figure 8: Superimposed structures of the top 5 stable conformers (76.8% total population) generated by CONFLE...
Figure 9: Key interactions that are supposed to control the spatial arrangement of the heterotricycle and the...
Figure 10: The future synthetic target 22 is expected to show potent neuroactivity.
Genomics-inspired discovery of massiliachelin, an agrochelin epimer from Massilia sp. NR 4-1
- Jan Diettrich,
- Hirokazu Kage and
- Markus Nett
Beilstein J. Org. Chem. 2019, 15, 1298–1303, doi:10.3762/bjoc.15.128
- yersiniabactin biosynthesis (Table S2, Supporting Information File 1), which led us to infer that the absolute configuration at C-19 is S. It was hence possible to predict the configuration of all stereocenters in 1 except C-15 by bioinformatics. To conclude the stereochemical analysis, we resorted to the NOESY
- genome of this bacterium. Bioinformatic analyses greatly facilitated the stereochemical analysis and also demonstrated the usefulness of computational methods in the configurational assignment of this class of natural products. Experimental Analytical methods LC–MS analyses were performed with a
Graphical Abstract
Figure 1: A) Organization of the micacocidin-type gene cluster from Massilia sp. NR 4-1 (top) and of the mic ...
Figure 2: Structures of massiliachelin (1), agrochelin (2), micacocidin (3), pyochelin I (4), pyochelin II (5...
Sacrolide A, a new antimicrobial and cytotoxic oxylipin macrolide from the edible cyanobacterium Aphanothece sacrum
- Naoya Oku,
- Miyako Matsumoto,
- Kohsuke Yonejima,
- Keijiroh Tansei and
- Yasuhiro Igarashi
Beilstein J. Org. Chem. 2014, 10, 1808–1816, doi:10.3762/bjoc.10.190
- . Initial derivatization strategy for the stereochemical analysis of sacrolide A (1). Determination of the stereochemistry of sacrolide A (1). Plausible biosynthesis of sacrolide A (1). 1H (500 MHz) and 13C (125 MHz) NMR data for sacrolide A (1) in CDCl3 (δ in ppm). Antimicrobial activity of sacrolide A (1
Graphical Abstract
Figure 1: Structure of sacrolide A (1).
Figure 2: Selected COSY (bold lines) and HMBC (arrows) correlations for sacrolide A (1).
Scheme 1: Initial derivatization strategy for the stereochemical analysis of sacrolide A (1).
Scheme 2: Determination of the stereochemistry of sacrolide A (1).
Scheme 3: Plausible biosynthesis of sacrolide A (1).
Figure 3: The effect of sacrolide A (1) on 3Y1 rat fibroblastic cells. (a) Control. (b) 45 min after exposure...
Figure 4: Extracted ion chromatograms for sacrolide A (1) molecular ion at m/z 307 [M – H]− in the LC–MS anal...
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.
Stereoselectivity of supported alkene metathesis catalysts: a goal and a tool to characterize active sites
- Christophe Copéret
Beilstein J. Org. Chem. 2011, 7, 13–21, doi:10.3762/bjoc.7.3
- how it evolves with time. Stereochemical analysis is therefore a powerful tool that will be exploited thereafter to obtain more information about supported catalysts. Stereoselectivity of heterogeneous alkene metathesis catalysts: a snapshot of the structures of active sites Well-defined silica
Graphical Abstract
Scheme 1: Alkene metathesis mechanism.
Scheme 2: Metathesis possibilities.
Scheme 3: Metathesis with Re-based alumina supported catalysts.
Figure 1: (E/Z) ratio as a function of conversion. a) MeReO3 supported on alumina and b) MeReO3 supported on ...
Scheme 4: Alkene selectivity of metathesis reactions.
Scheme 5: Hybrid organic–inorganic catalyst containing a Ru–NHC unit.
