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Search for "naphthalene" in Full Text gives 197 result(s) in Beilstein Journal of Organic Chemistry.
Targeting the Pseudomonas quinolone signal quorum sensing system for the discovery of novel anti-infective pathoblockers
- Christian Schütz and
- Martin Empting
Beilstein J. Org. Chem. 2018, 14, 2627–2645, doi:10.3762/bjoc.14.241
- benzimidazole moiety (compound not shown) [80]. In a follow-up patent they generated PqsR inhibitor 45 as a front-runner compound [81], in which the benzimidazole headgroup was replaced by a substituted naphthalene bearing a carboxamide, in analogy to a fragment 44 of Zender et al. [82] and similar to the
Graphical Abstract
Figure 1: The four quorum sensing systems in P. aeruginosa las, iqs, rhl, and pqs. Abbreviations: OdDHL, N-(3...
Figure 2: Schematic overview of the PQS biosynthesis and involvement of related metabolites and PqsE in virul...
Figure 3: Anthranilic acid (1) and derivatives thereof (2–4).
Figure 4: Crystal structure of 6-FABA-AMP in complex with PqsA.
Figure 5: Structures of substrate mimetic PqsA inhibitors.
Figure 6: Structures and characteristics of prominent classes of PqsD inhibitors.
Figure 7: Comparison of docking poses of three prototypic PqsD inhibitors: benzamidobenzoic acid derivative 12...
Figure 8: Structures and characteristics of hits against PqsD identified through different methods.
Figure 9: HHQ and PQS analogues as PqsD inhibitors and chemical probe used for screening.
Figure 10: Structure of PqsD-targeting biofilm inhibitor derived from linezolid.
Figure 11: Fragment-based PqsE-inhibitors 24–26.
Figure 12: PqsE co-crystal structures. (A) native product 2-ABA; (B–D) hit fragments 24–26.
Figure 13: Structurally diverse PqsBC-inhibitors 27–30.
Figure 14: Native PqsR ligand HHQ (31) which is converted into PQS (32) by PqsH and synthetic inhibitors 33 an...
Figure 15: Quinazolinone inhibitor 36 (QZN).
Figure 16: Crystal structure of QZN (36) in complex with PqsRCBD.
Figure 17: Structures of best fitting compounds 37–40 obtained from docking studies.
Figure 18: Initial hit 21 and optimized compound 42 (M64).
Figure 19: Co-crystal structure of M64 (42) with PqsRLBD.
Figure 20: M64 (42) as the starting point for further optimization leading to 43, which was further modified a...
Figure 21: Hit fragments from the benzamide (47–48) and oxadiazole class (49–51).
Figure 22: Structures of dual inhibitors 52–55.
Figure 23: Sulfonyl pyrimidines 56–58 acting as dual PqsD/PqsR inhibitors.
Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps
- Sambasivarao Kotha,
- Milind Meshram and
- Chandravathi Chakkapalli
Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223
- precursor 9 to [Ru-2] catalyst 5 gave the ring-closure product 10 in quantitative yield (Scheme 1). A sequential usage of SM cross coupling and RCM was responsible to construct various naphthalene derivatives such as 15 [31]. The SM coupling product 3,4-diallylbenzene derivative 13 (90%) was obtained from
Graphical Abstract
Figure 1: Various catalysts used for metathesis reactions.
Scheme 1: SM coupling and RCM protocol to substituted indene derivative 10.
Scheme 2: Synthesis of polycycles via SM and RCM approach.
Figure 2: Various angucyclines.
Scheme 3: SM coupling and RCM protocol to the benz[a]anthracene skeleton 26.
Scheme 4: Synthesis of substituted spirocycles via RCM and SM sequence.
Scheme 5: Synthesis of highly functionalized bis-spirocyclic derivative 37.
Scheme 6: Synthesis of spirofluorene derivatives via RCM and SM coupling sequence.
Scheme 7: Synthesis of truxene derivatives via RCM and SM coupling.
Scheme 8: Synthesis of substituted isoquinoline derivative via SM and RCM protocol.
Scheme 9: Synthesis to 8-aryl substituted coumarin 64 via RCM and SM sequence.
Scheme 10: Synthesis of cyclic sulfoximine 70 via SM and RCM as key steps.
Scheme 11: Synthesis of 1-benzazepine derivative 75 via SM and RCM as key steps.
Scheme 12: Synthesis of naphthoxepine derivative 79 via RCM followed by SM coupling.
Scheme 13: Sequential CM and SM coupling approach to Z-stilbene derivative 85.
Scheme 14: Synthesis of substituted trans-stilbene derivatives via SM coupling and RCM.
Scheme 15: Synthesis of biaryl derivatives via sequential EM, DA followed by SM coupling.
Scheme 16: Synthesis of the dibenzocyclooctadiene core of schisandrene.
Scheme 17: Synthesis of cyclophane 115 via SM coupling and RCM as key steps.
Scheme 18: Synthesis of cyclophane 120 and 122 via SM coupling and RCM as key steps.
Scheme 19: Synthesis of cyclophanes via SM and RCM.
Scheme 20: Synthesis of MK-6325 (141) via RCM and SM coupling.
Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules
- Hendrik V. Schröder and
- Christoph A. Schalley
Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190
- possibility of orthogonal switching (redox and light) enables an electrochemical “writing” of data which can be subsequently locked by a light stimulus. The TTF-based doubly interlocked crown/ammonium rotaxane 19 recently reported by us consists of a divalent axle with a π-electron-poor central naphthalene
Graphical Abstract
Figure 1: The two one-electron oxidation reactions of tetrathiafulvalene (TTF, 1) and the corresponding prope...
Figure 2: UV–vis spectra and photographs of TTF 2 in its three stable oxidation states (black line = 2, orang...
Figure 3: Structure and conformations of two TTF dimers in solution, the mixed-valence and the radical-cation...
Figure 4: (a) The isomerism problem of TTF. (b)–(d) Major synthetic breakthroughs for the construction of TTF...
Figure 5: (a) Host–guest equilibrium between π-electron-poor cyclophane 3 and different TTFs with their corre...
Figure 6: TTF complexes with different host molecules.
Figure 7: Stable TTF (a) radical-cation and (b) mixed-valence dimers in confined molecular spaces.
Figure 8: A “three-pole supramolecular switch”: Controlled by its oxidation state, TTF (1) jumps back and for...
Figure 9: Redox-controlled closing and opening motion of the artificial molecular lasso 12.
Figure 10: Graphical illustration how a non-degenerate TTF-based shuttle works under electrochemical operation....
Figure 11: The first TTF-based rotaxane 13.
Figure 12: A redox-switchable bistable molecular shuttle 14.
Figure 13: The redox-switchable cyclodextrin-based rotaxane 15.
Figure 14: The redox-switchable non-ionic rotaxane 16 with a pyromellitic diimide macrocycle.
Figure 15: The redox-switchable TTF rotaxane 17 based on a crown/ammonium binding motif.
Figure 16: Structure and operation of the electro- and photochemically switchable rotaxane 18 which acts as po...
Figure 17: (a) The redox-switchable rotaxane 19 with a donor–acceptor pair which is stable in five different s...
Figure 18: Schematic representation of a molecular electronic memory based on a bistable TTF-based rotaxane. (...
Figure 19: Schematic representation of bending motion of a microcantilever beam with gold surface induced by o...
Figure 20: TTF-dimer interactions in a redox-switchable tripodal [4]rotaxane 22.
Figure 21: (a) A molecular friction clutch 23 which can be operated by electrochemical stimuli. (b) Schematic ...
Figure 22: Fusion between rotaxane and catenane: a [3]rotacatenane 24 which can stabilize TTF dimers.
Figure 23: The first TTF-based catenane 25.
Figure 24: Electrochemically controlled circumrotation of the bistable catenane 26.
Figure 25: A tristable switch based on the redox-active [2]catenane 27 with three different stations.
Figure 26: Structure of catenane-functionalized MOF NU-1000 [108] with structural representation of subcomponents. ...
Figure 27: (a) [3]Catenanes 29 and 30 which can stabilize mixed-valence or radical-cation dimers of TTF. (b) S...
Cobalt-catalyzed peri-selective alkoxylation of 1-naphthylamine derivatives
- Jiao-Na Han,
- Cong Du,
- Xinju Zhu,
- Zheng-Long Wang,
- Yue Zhu,
- Zhao-Yang Chu,
- Jun-Long Niu and
- Mao-Ping Song
Beilstein J. Org. Chem. 2018, 14, 2090–2097, doi:10.3762/bjoc.14.183
- provide the intermediate B. Subsequently, the transfer of ligand OR from the coordinated CoIII to the naphthalene ring led to the formation of intermediate C. Finally, the alkoxylated product 3aa was released accompanied with the deprotonation and the CoII species was transformed into the CoIII species by
Graphical Abstract
Figure 1: Strategies for cobalt-catalyzed alkoxylation.
Scheme 1: Reaction scope with respect to N-(naphthalen-1-yl)picolinamide derivatives. Reaction conditions: 1 ...
Scheme 2: Reaction scope with respect to alcohols. Reaction conditions: 1a (0.2 mmol), 2 (1.0 mL), CoF2 (20 m...
Scheme 3: Control experiments and mechanistic studies.
Scheme 4: Proposed reaction mechanism.
Scheme 5: Removal of the directing group.
A conformationally adaptive macrocycle: conformational complexity and host–guest chemistry of zorb[4]arene
- Liu-Pan Yang,
- Song-Bo Lu,
- Arto Valkonen,
- Fangfang Pan,
- Kari Rissanen and
- Wei Jiang
Beilstein J. Org. Chem. 2018, 14, 1570–1577, doi:10.3762/bjoc.14.134
- macrocycles possess multiple conformers due to the naphthalene flipping in analogy with the phenyl-ring flipping seen in the more common calixarenes. The conformers so formed undergo quick interconversion and each one has a slightly different cavity. Thus, these conformers consist of a complex conformational
- guests and the four naphthalene rings of the host should still be the major driving force as mentioned above. However, it was noticed that the distances between diagonal linker oxygen atoms in the backbone of the host are slightly different for the four complexes. These interactions may be tuned by the
- = −0.13, R2 = 0.9956) and TΔS (right, slope = 0.93, R2 = 0.9976). (a) Chemical structures of ZB4 and the guests involved in this research. The counterions are PF6−. (b) The four representative conformers of ZB4 resulting from naphthalene flipping. Numberings on the structures are used to assign NMR
Graphical Abstract
Scheme 1: (a) Chemical structures of ZB4 and the guests involved in this research. The counterions are PF6−. ...
Figure 1: X-ray single crystal structure of ZB4 and the host–guest complexes. a) ZB4, b) 2+@ZB4-IV, c) 3+@ZB4...
Figure 2: Parabolic free-energy relationship between log(KR/KH) and Hammett parameter σp. KR: guests 11+–21+; ...
Figure 3: X-ray single crystal structures of 14+@ZB4-III, 16+@ZB4-III, 18+@ZB4-III and 21+@ZB4-III. Butyl gro...
Figure 4: X-ray single crystal structures of 18+@ZB4-III and 18+ in 18+@ZB4-III.
Figure 5: Linear relationships of ΔH with temperature (left, slope = −0.13, R2 = 0.9956) and TΔS (right, slop...
Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials
- Alberto Spinella,
- Marco Russo,
- Antonella Di Vincenzo,
- Delia Chillura Martino and
- Paolo Lo Meo
Beilstein J. Org. Chem. 2018, 14, 1498–1507, doi:10.3762/bjoc.14.127
- (bromocresol green, 8), a bis-indole (indigo carmine, 9) and a naphthalene-bis-diazoic (naphthol blue-black, 10), in order to evaluate the outcome of molecular size, shape and electric charge. Dyes can be considered suitable and easily detectable models of pollutants [43][44][45][46][47], for the removal of
Graphical Abstract
Scheme 1: Structures of: a) calixarene Ca-OP; b) alkyl diazides A1–A4.
Scheme 2: Structures of p-nitroaniline derivatives 1–5 and dyes 6–10.
Figure 1: FTIR spectra of Ca-OP (red), A2 (green) and CaNS2 (blue).
Figure 2: a) 13C{1H} CP-MAS NMR spectra of CaNSs; b) signal attributions.
Figure 3: Selection of SEM micrographs for materials for CaNS1 (a), CaNS2 (b), CaNS3 (c) and CaNS4 (d).
A survey of chiral hypervalent iodine reagents in asymmetric synthesis
- Soumen Ghosh,
- Suman Pradhan and
- Indranil Chatterjee
Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107
- new kind of binaphthyl-based chiral I(III) prereagent 19 with the 8 and 8′ positions of the naphthalene substituents being occupied by iodide. Here they have observed that this chiral hypervalent iodine reagent 19 in the presence of co-oxidant m-CBPA is very useful for the dearomatizing
Graphical Abstract
Scheme 1: An overview of different chiral iodine reagents or precursors thereof.
Scheme 2: Asymmetric oxidation of sulfides by chiral hypervalent iodine reagents.
Scheme 3: Oxidative dearomatization of naphthol derivatives by Kita et al.
Scheme 4: [4 + 2] Diels–Alder dimerization reported by Birman et al.
Scheme 5: m-CPBA guided catalytic oxidative naphthol dearomatization.
Scheme 6: Oxidative dearomatization of phenolic derivatives by Ishihara et al.
Scheme 7: Oxidative spirocyclization applying precatalyst 11 developed by Ciufolini et al.
Scheme 8: Asymmetric hydroxylative dearomatization.
Scheme 9: Enantioselective oxylactonization reported by Fujita et al.
Scheme 10: Dioxytosylation of styrene (47) by Wirth et al.
Scheme 11: Oxyarylation and aminoarylation of alkenes.
Scheme 12: Asymmetric diamination of alkenes.
Scheme 13: Stereoselective oxyamination of alkenes reported by Wirth et al.
Scheme 14: Enantioselective and regioselective aminofluorination by Nevado et al.
Scheme 15: Fluorinated difunctionalization reported by Jacobsen et al.
Scheme 16: Aryl rearrangement reported by Wirth et al.
Scheme 17: α-Arylation of β-ketoesters.
Scheme 18: Asymmetric α-oxytosylation of carbonyls.
Scheme 19: Asymmetric α-oxygenation and α-amination of carbonyls reported by Wirth et al.
Scheme 20: Asymmetric α-functionalization of ketophenols using chiral quaternary ammonium (hypo)iodite salt re...
Scheme 21: Oxidative Intramolecular coupling by Gong et al.
Scheme 22: α-Sulfonyl and α-phosphoryl oxylation of ketones reported by Masson et al.
Scheme 23: α-Fluorination of β-keto esters.
Scheme 24: Alkynylation of β-ketoesters and amides catalyzed by phase-transfer catalyst.
Scheme 25: Alkynylation of β-ketoesters and dearomative alkynylation of phenols.
One hundred years of benzotropone chemistry
- Arif Dastan,
- Haydar Kilic and
- Nurullah Saracoglu
Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98
- reported that the oxidative amination of 2,3-benzotropone (12) with methylcopperamine sulfate in aqueous methylamine at room temperature afforded 4-methylamino-1-naphthalene carbaldehyde (215) with a trace amount of 4-methylamino-2,3-benzotropone (214) via reaction paths including the dishing of Michael
Graphical Abstract
Scheme 1: Tropone (1), tropolone (2) and their resonance structures.
Figure 1: Natural products containing a tropone nucleus.
Figure 2: Possible isomers 11–13 of benzotropone.
Scheme 2: Synthesis of benzotropones 11 and 12.
Scheme 3: Oxidation products of benzotropylium fluoroborate (16).
Scheme 4: Oxidation of 7-bromo-5H-benzo[7]annulene (22).
Scheme 5: Synthesis of 4,5-benzotropone (11) using o-phthalaldehyde (27).
Scheme 6: Synthesis of 4,5-benzotropone (11) starting from oxobenzonorbornadiene 31.
Scheme 7: Acid-catalyzed cleavage of oxo-bridge of 34.
Scheme 8: Synthesis of 4,5-benzotropone (11) from o-xylylene dibromide (38).
Scheme 9: Synthesis of 4,5-benzotropone (11) via the carbene adduct 41.
Scheme 10: Heck coupling strategy for the synthesis of 11.
Scheme 11: Synthesis of benzofulvalenes via carbonyl group of 4,5-benzotropone (11).
Figure 3: Some cycloheptatrienylium cations.
Scheme 12: Synthesis of condensation product 63 and its subsequent oxidative cyclization products.
Figure 4: A novel series of benzo[7]annulenes prepared from 4,5-benzotropone (11).
Scheme 13: Preparation of substituted benzo[7]annulene 72 using the Mukaiyama-Michael reaction.
Figure 5: Possible benzo[7]annulenylidenes 73–75.
Scheme 14: Thermal and photochemical decomposition of 7-diazo-7H-benzo[7]annulene (76) and the trapping of int...
Scheme 15: Synthesis of benzoheptafulvalene 86.
Scheme 16: Synthesis of 7-(diphenylmethylene)-7H-benzo[7]annulene (89).
Scheme 17: Reaction of 4,5-benzotropone (11) with dimethyl diazomethane.
Scheme 18: Synthesis of dihydrobenzomethoxyazocine 103.
Scheme 19: Synthesis and reducibility of benzo-homo-2-methoxyazocines.
Scheme 20: Synthesis of 4,5-benzohomotropones 104 and 115 from 4,5-benzotropones 11 and 113.
Scheme 21: A catalytic deuterogenation of 4,5-benzotropone (11) and synthesis of 5-monosubstituted benzo[7]ann...
Scheme 22: Synthesis of methyl benzo[7]annulenes 131 and 132.
Scheme 23: Ambident reactivity of halobenzo[7]annulenylium cations 133a/b.
Scheme 24: Preparation of benzo[7]annulenylidene–iron complexes 147.
Scheme 25: Synthesis of 1-ethynylbenzotropone (150) and the etheric compound 152 from 4,5-benzotropone (11) wi...
Scheme 26: Thermal decomposition of 4,5-benzotropone (11).
Scheme 27: Reaction of 4,5-benzotropone (11) with 1,2-ethanediol and 1,2-ethanedithiol.
Scheme 28: Conversions of 1-benzosuberone (162) to 2,3-benzotropone (12).
Scheme 29: Synthesis strategies for 2,3-bezotropone (12) using 1-benzosuberones.
Scheme 30: Oxidation-based synthesis of 2,3-benzotropone (12) via 1-benzosuberone (162).
Scheme 31: Synthesis of 2,3-benzotropone (12) from α-tetralone (171) via ring-expansion.
Scheme 32: Preparation of 2,3-benzotropone (12) by using of benzotropolone 174.
Figure 6: Benzoheptafulvenes as condensation products of 2,3-benzotropone (12).
Scheme 33: Conversion of 2,3-benzotropone (12) to tosylhydrazone salt 182 and gem-dichloride 187.
Figure 7: Benzohomoazocines 191–193 and benzoazocines 194–197.
Scheme 34: From 2,3-benzotropone (12) to carbonium ions 198–201.
Scheme 35: Cycloaddition reactions of 2,3-benzotropone (12).
Scheme 36: Reaction of 2,3-benzotropone (12) with various reagents and compounds.
Figure 8: 3,4-Benzotropone (13) and its resonance structure.
Scheme 37: Synthesis of 6,7-benzobicyclo[3.2.0]hepta-3,6-dien-2-one (230).
Figure 9: Photolysis and thermolysis products of 230.
Figure 10: Benzotropolones and their tautomeric structures.
Scheme 38: Synthesis strategies of 4,5-benzotropolone (238).
Scheme 39: Synthesis protocol for 2-hydroxy-4,5-benzotropone (238) using oxazole-benzo[7]annulene 247.
Figure 11: Some quinoxaline and pyrazine derivatives 254–256 prepared from 4,5-benzotropolone (238).
Scheme 40: Nitration product of 4,5-benzotropolone (238) and its isomerization to 1-nitro-naphthoic acid (259)....
Scheme 41: Synthesis protocol for 6-hydroxy-2,3-benzotropone (239) from benzosuberone (162).
Scheme 42: Various reactions via 6-hydroxy-2,3-benzotropone (239).
Scheme 43: Photoreaction of 6-hydroxy-2,3-benzotropone (239).
Scheme 44: Synthesis of 7-hydroxy-2,3-benzotropone (241) from benzosuberone (162).
Scheme 45: Synthesis strategy for 7-hydroxy-2,3-benzotropone (241) from ketone 276.
Scheme 46: Synthesis of 7-hydroxy-2,3-benzotropone (241) from β-naphthoquinone (280).
Scheme 47: Synthesis of 7-hydroxy-2,3-benzotropone (241) from bicyclic endoperoxide 213.
Scheme 48: Synthesis of 7-hydroxy-2,3-benzotropone (241) by ring-closing metathesis.
Figure 12: Various monosubstitution products 289–291 of 7-hydroxy-2,3-benzotropone (241).
Scheme 49: Reaction of 7-hydroxy-2,3-benzotropone (241) with various reagents.
Scheme 50: Synthesis of 4-hydroxy-2,3-benzotropones 174 and 304 from diketones 300/301.
Scheme 51: Catalytic hydrogenation of diketones 300 and 174.
Scheme 52: Synthesis of halo-benzotropones from alkoxy-naphthalenes 306, 307 and 310.
Figure 13: Unexpected byproducts 313–315 during synthesis of chlorobenzotropone 309.
Figure 14: Some halobenzotropones and their cycloadducts.
Scheme 53: Multisep synthesis of 2-chlorobenzotropone 309.
Scheme 54: A multistep synthesis of 2-bromo-benzotropone 26.
Scheme 55: A multistep synthesis of bromo-2,3-benzotropones 311 and 316.
Scheme 56: Oxidation reactions of 8-bromo-5H-benzo[7]annulene (329) with some oxidants.
Scheme 57: Synthesis of 2-bromo-4,5-benzotropone (26).
Scheme 58: Synthesis of 6-chloro-2,3-benzotropone (335) using LiCl and proposed intermediate 336.
Scheme 59: Reaction of 7-bromo-2,3-benzotropone (316) with methylamine.
Scheme 60: Reactions of bromo-2,3-benzotropones 26 and 311 with dimethylamine.
Scheme 61: Reactions of bromobenzotropones 311 and 26 with NaOMe.
Scheme 62: Reactions of bromobenzotropones 26 and 312 with t-BuOK in the presence of DPIBF.
Scheme 63: Cobalt-catalyzed reductive cross-couplings of 7-bromo-2,3-benzotropone (316) with cyclic α-bromo en...
Figure 15: Cycloadduct 357 and its di-π-methane rearrangement product 358.
Scheme 64: Catalytic hydrogenation of 2-chloro-4,5-benzotropone (311).
Scheme 65: Synthesis of dibromo-benzotropones from benzotropones.
Scheme 66: Bromination/dehydrobromination of benzosuberone (162).
Scheme 67: Some transformations of isomeric dibromo-benzotropones 261A/B.
Scheme 68: Transformations of benzotropolone 239B to halobenzotropolones 369–371.
Figure 16: Bromobenzotropolones 372–376 and 290 prepared via bromination/dehydrobromination strategy.
Scheme 69: Synthesis of some halobenzotropolones 289, 377 and 378.
Figure 17: Bromo-chloro-derivatives 379–381 prepared via chlorination.
Scheme 70: Synthesis of 7-iodo-3,4-benzotropolone (382).
Scheme 71: Hydrogenation of bromobenzotropolones 369 and 370.
Scheme 72: Debromination reactions of mono- and dibromides 290 and 375.
Figure 18: Nitratation and oxidation products of some halobenzotropolenes.
Scheme 73: Azo-coupling reactions of some halobenzotropolones 294, 375 and 378.
Figure 19: Four possible isomers of dibenzotropones 396–399.
Figure 20: Resonance structures of tribenzotropone (400).
Scheme 74: Two synthetic pathways for tribenzotropone (400).
Scheme 75: Synthesis of tribenzotropone (400) from dibenzotropone 399.
Scheme 76: Synthesis of tribenzotropone (400) from 9,10-phenanthraquinone (406).
Scheme 77: Synthesis of tribenzotropone (400) from trifluoromethyl-substituted arene 411.
Figure 21: Dibenzosuberone (414).
Figure 22: Reduction products 415 and 416 of tribenzotropone (400).
Figure 23: Structures of tribenzotropone dimethyl ketal 417 and 4-phenylfluorenone (412) and proposed intermed...
Figure 24: Structures of benzylidene- and methylene-9H-tribenzo[a,c,e][7]annulenes 419 and 420 and chiral phos...
Figure 25: Structures of tetracyclic alcohol 422, p-quinone methide 423 and cation 424.
Figure 26: Structures of host molecules 425–427.
Scheme 78: Synthesis of non-helical overcrowded derivatives syn/anti-431.
Figure 27: Hexabenzooctalene 432.
Figure 28: Structures of possible eight isomers 433–440 of naphthotropone.
Scheme 79: Synthesis of naphthotropone 437 starting from 1-phenylcycloheptene (441).
Scheme 80: Synthesis of 10-hydroxy-11H-cyclohepta[a]naphthalen-11-one (448) from diester 445.
Scheme 81: Synthesis of naphthotropone 433.
Scheme 82: Synthesis of naphthotropones 433 and 434 via cycloaddition reaction.
Scheme 83: Synthesis of naphthotropone 434 starting from 452.
Figure 29: Structures of tricarbonyl(tropone)irons 458, and possible cycloadducts 459.
Scheme 84: Synthesis of naphthotropone 436.
Scheme 85: Synthesis of precursor 465 for naphthotropone 435.
Scheme 86: Generation of naphthotropone 435 from 465.
Figure 30: Structures of tropylium cations 469 and 470.
Figure 31: Structures of tropylium ions 471+.BF4−, 472+.BF4−, and 473+.BF4−.
Scheme 87: Synthesis of tropylium ions 471+.BF4− and 479+.ClO4−.
Scheme 88: Synthesis of 1- and 2-methylanthracene (481 and 482) via carbene–carbene rearrangement.
Figure 32: Trapping products 488–490.
Scheme 89: Generation and chemistry of a naphthoannelated cycloheptatrienylidene-cycloheptatetraene intermedia...
Scheme 90: Proposed intermediates and reaction pathways for adduct 498.
Scheme 91: Exited-state intramolecular proton transfer of 505.
Figure 33: Benzoditropones 506 and 507.
Scheme 92: Synthesis of benzoditropone 506e.
Scheme 93: Synthetic approaches for dibenzotropone 507 via tropone (1).
Scheme 94: Formation mechanisms of benzoditropone 507 and 516 via 515.
Scheme 95: Synthesis of benzoditropones 525 and 526 from pyromellitic dianhydride (527).
Figure 34: Possible three benzocyclobutatropones 534–536.
Scheme 96: Synthesis of benzocyclobutatropones 534 and 539.
Scheme 97: Synthesis attempts for benzocyclobutatropone 545.
Scheme 98: Generation and trapping of symmetric benzocyclobutatropone 536.
Scheme 99: Synthesis of chloro-benzocyclobutatropone 552 and proposed mechanism of fluorenone derivatives.
Scheme 100: Synthesis of tropolone analogue 559.
Scheme 101: Synthesis of tropolones 561 and 562.
Figure 35: o/p-Tropoquinone rings (563 and 564) and benzotropoquinones (565–567).
Scheme 102: Synthesis of benzotropoquinone 566.
Scheme 103: Synthesis of benzotropoquinone 567 via a Diels–Alder reaction.
Figure 36: Products 575–577 through 1,2,3-benzotropoquinone hydrate 569.
Scheme 104: Structures 578–582 prepared from tropoquinone 567.
Figure 37: Two possible structures 583 and 584 for dibenzotropoquinone, and precursor compound 585 for 583.
Scheme 105: Synthesis of saddle-shaped ketone 592 using dibenzotropoquinone 584.
Synthetic avenues towards a tetrasaccharide related to Streptococcus pneumonia of serotype 6A
- Aritra Chaudhury,
- Mana Mohan Mukherjee and
- Rina Ghosh
Beilstein J. Org. Chem. 2018, 14, 1095–1102, doi:10.3762/bjoc.14.95
- ). Subsequently, 10 was subjected to naphthylmethylation/p-methoxybenzylation [32] with 2-(bromomethyl)naphthalene (NapBr)/p-methoxybenzyl chloride in DMF to afford 6a/11 [32] in 90% and 80% yields, respectively. These derivatives were next subjected to thioglycoside hydrolysis using trichloroisocyanuric acid
Graphical Abstract
Figure 1: The tetrasaccharides associated with the pneumonicoccal serogroup 6.
Figure 2: Retrosynthetic analysis.
Scheme 1: Preparation of D-glucosyl donor 6. Reaction conditions: a) NapBr/PMBCl, NaH, DMF, rt, 12 h, 90% (6a...
Scheme 2: Preparation of L-rhamnosyl acceptor 5. Reaction conditions: a) Py, BzCl, rt, 12 h, 99%; b) DDQ, DCM...
Scheme 3: Preparation of ribitol acceptor 7. Reaction conditions: a) Me2C(OMe)2, pTSA, CH3COCH3, rt, 81%; b) ...
Scheme 4: Stepwise synthesis of tetrasaccharide 1. Reaction conditions: a) TMSOTf, DCM/Et2O (5:1), 4 Å MS, −3...
Scheme 5: One-pot synthesis of tetrasaccharide 1. Reaction conditions: a) TMSOTf, 4 Å MS, DCM/Et2O (4:1), N2,...
An overview of recent advances in duplex DNA recognition by small molecules
- Sayantan Bhaduri,
- Nihar Ranjan and
- Dev P. Arya
Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93
- and its cytotoxicity was attributed to DNA minor groove binding ability [105]. Recently, Schmuck et al. have developed a first prototype of cationic oligopeptide-based molecular beacon (conjugate 43) coupled with a FRET pair, a naphthalene donor and a dansyl acceptor, for ratiometric detection of ds
Graphical Abstract
Figure 1: A figure showing the hydrogen bonding patterns observed in (a) duplex (b) triplex and (c) quadruple...
Figure 2: (a) Portions of MATα1–MATα2 are shown contacting the minor groove of the DNA substrate. Key arginin...
Figure 3: Chemical structures of naturally occurring and synthetic hybrid minor groove binders.
Figure 4: Synthetic structural analogs of distamycin A by replacing one or more pyrrole rings with other hete...
Figure 5: Pictorial representation of the binding model of pyrrole–imidazole (Py/Im) polyamides based on the ...
Figure 6: Chemical structures of synthetic “hairpin” pyrrole–imidazole (Py/Im) conjugates.
Figure 7: (a) Minor groove complex formation between DNA duplex and 8-ring cyclic Py/Im polyamide (conjugate ...
Figure 8: Telomere-targeting tandem hairpin Py/Im polyamides 23 and 24 capable of recognizing >10 base pairs; ...
Figure 9: Representative examples of recently developed DNA minor groove binders.
Figure 10: Chemical structures of bisbenzamidazoles Hoechst 33258 and 33342 and their synthetic structural ana...
Figure 11: Chemical structures of bisamidines such as diminazene, DAPI, pentamidine and their synthetic struct...
Figure 12: Representative examples of recently developed bisamidine derivatives.
Figure 13: Chemical structures of chromomycin, mithramycin and their synthetic structural analogs 91 and 92.
Figure 14: Chemical structures of well-known naturally occurring DNA binding intercalators.
Figure 15: Naturally occurring indolocarbazole rebeccamycin and its synthetic analogs.
Figure 16: Representative examples of naturally occurring and synthetic derivatives of DNA intercalating agent...
Figure 17: Several recent synthetic varieties of DNA intercalators.
Figure 18: Aminoglycoside (neomycin)–Hoechst 33258/intercalator conjugates.
Figure 19: Chemical structures of triazole linked neomycin dimers and neomycin–bisbenzimidazole conjugates.
Figure 20: Representative examples of naturally occurring and synthetic analogs of DNA binding alkylating agen...
Figure 21: Chemical structures of naturally occurring and synthetic analogs of pyrrolobenzodiazepines.
Electrochemically modified Corey–Fuchs reaction for the synthesis of arylalkynes. The case of 2-(2,2-dibromovinyl)naphthalene
- Fabiana Pandolfi,
- Isabella Chiarotto and
- Marta Feroci
Beilstein J. Org. Chem. 2018, 14, 891–899, doi:10.3762/bjoc.14.76
- Fabiana Pandolfi Isabella Chiarotto Marta Feroci Deptartment of Fundamental and Applied Sciences for Engineering (SBAI), Sapienza University of Rome, via Castro Laurenziano, 7, 00161, Rome, Italy 10.3762/bjoc.14.76 Abstract The electrochemical reduction of 2-(2,2-dibromovinyl)naphthalene in a DMF
- solution (Pt cathode) yields selectively 2-ethynylnaphthalene or 2-(bromoethynyl)naphthalene in high yields, depending on the electrolysis conditions. In particular, by simply changing the working potential and the supporting electrolyte, the reaction can be directed towards the synthesis of the terminal
- alkyne (Et4NBF4) or the bromoalkyne (NaClO4). This study allowed to establish that 2-(bromoethynyl)naphthalene can be converted into 2-ethynylnaphthalene by cathodic reduction. Keywords: arylalkyne; carbon–bromine bond cleavage; cathodic reduction; Corey–Fuchs reaction; 2-(2,2-dibromovinyl)naphthalene
Graphical Abstract
Scheme 1: The Corey–Fuchs reaction.
Scheme 2: Electrochemical reduction of a carbon–halogen bond.
Scheme 3: Electrochemical synthesis of vinyl bromides [25].
Scheme 4: Scope of this work.
Figure 1: Voltammetric curves of 1a 0.020 mol dm−3; Pt, glassy carbon (GC) or Ag cathode. ν = 0.2 V s−1, T = ...
Scheme 5: Possible products from the electrolysis of 2-(2,2-dibromovinyl)naphthalene (1a).
Figure 2: Variation of the amounts of 1a, 2a, and 3a with the number of Faradays of 1a.
Scheme 6: Mechanistic hypothesis for the synthesis of alkyne 2a and bromoalkyne 3a from 2-(2,2-dibromovinyl)n...
Scheme 7: Possible reaction using NaClO4 as supporting electrolyte.
Scheme 8: Electrochemical synthesis of 9-ethyl-3-ethynyl-9H-carbazole (2b).
Scheme 9: Electrochemical synthesis of 1-ethynyl-4-methoxybenzene (2c).
Bromide-assisted chemoselective Heck reaction of 3-bromoindazoles under high-speed ball-milling conditions: synthesis of axitinib
- Jingbo Yu,
- Zikun Hong,
- Xinjie Yang,
- Yu Jiang,
- Zhijiang Jiang and
- Weike Su
Beilstein J. Org. Chem. 2018, 14, 786–795, doi:10.3762/bjoc.14.66
- coupling product 3oa (70%). Besides, N-unsubstituted indazole 1n could also be tolerated in this reaction giving 3na (52%) and 3nf (49%) in moderate yield by using 1,8-bis(dimethylamino)naphthalene as a base. To our delight, 3-chloroindazole could also be activated in this reaction, giving the
- 207 stainless-steel balls (dMB = 6 mm, ФMB = 0.293), milling at 800 rpm for 90 min. aN-Boc-3-bromoindazole was used as substrate. b150 min. c700 rpm. d3-chloro-1-methyl-1H-indazole was used as substrate, νrot = 900 rpm. e1,8-Bis(dimethylamino)naphthalene was used as base. Synthesis of axitinib by
Graphical Abstract
Scheme 1: Representative pharmaceutically useful indazoles.
Scheme 2: Model Heck reaction of 3-bromo-N-methyl-1H-indazole (1a) and n-butyl acrylate (2a). (173 stainless-...
Figure 1: Investigation of additives in the Heck reaction: 1a (1.5 mmol), 2a (2.25 mmol), Pd(OAc)2 (5 mol %),...
Scheme 3: The control experiments. aTEA (1.8 mmol), silica gel (5.0 g), bPd(OAc)2 (5 mol %), PPh3 (10 mol %),...
Scheme 4: Plausible reaction pathway.
Figure 2: Influence of milling time and rotation speed on the Heck reaction: 1a (1.5 mmol), 2a (2.25 mmol), P...
Figure 3: Influence of the milling ball filling degree with different size on the Heck reaction: 1a (1.5 mmol...
Scheme 5: Examination of the substrate scope. Reaction conditions: 1 (1.5 mmol), 2 (2.25 mmol), Pd(OAc)2 (5 m...
Scheme 6: Synthesis of axitinib by mechanochemical Heck–Migita coupling. Reagents and conditions: (i) NBS, Na...
An air-stable bisboron complex: a practical bidentate Lewis acid catalyst
- Longcheng Hong,
- Sebastian Ahles,
- Andreas H. Heindl,
- Gastelle Tiétcha,
- Andrey Petrov,
- Zhenpin Lu,
- Christian Logemann and
- Hermann A. Wegner
Beilstein J. Org. Chem. 2018, 14, 618–625, doi:10.3762/bjoc.14.48
- yields of the substituted naphthalene 5e were comparable between the two bidentate Lewis acid catalysts (Table 1, entry 5). The binding of pyridazine (1j) with bisboron compound A, seems to be too strong to engage a fast ligand exchange with phthalazine (3). Recently we have demonstrated that catalyst A
Graphical Abstract
Scheme 1: Bidentate bisborane Lewis acids.
Scheme 2: Complexation reaction of 5,10-dimethyl-5,10-dihydroboranthrene (A) with Lewis bases analyzed by NMR...
Figure 1: Time-dependent 1H NMR spectra of the air-exposed complex B.
Scheme 3: Synthetic procedures of bisboranes A and B.
Figure 2: ORTEP drawing (50% probability) of complex B.
Figure 3: UV–vis spectrum of complex B was measured in CHCl3 and compared with pyridazine and bisborane A (co...
The selective electrochemical fluorination of S-alkyl benzothioate and its derivatives
- Shunsuke Kuribayashi,
- Tomoyuki Kurioka,
- Shinsuke Inagi,
- Ho-Jung Lu,
- Biing-Jiun Uang and
- Toshio Fuchigami
Beilstein J. Org. Chem. 2018, 14, 389–396, doi:10.3762/bjoc.14.27
- , Rozhkov and Laurent reported an electrochemical partial fluorination of naphthalene and olefins about 30 years ago [5][6]. However, at that time, there has been no report on the anodic fluorination of heteroatom-containing compounds. At almost the same time, we found that the anodic α-methoxylation of
Graphical Abstract
Figure 1: Cyclic voltammograms of 0.1 M Bu4NBF4/MeCN with a Pt disk working electrode in the absence (brown l...
Figure 2: Calculated HOMO diagram of 1a.
Figure 3: Calculated HOMO diagrams of 1h, 1i and 1j.
Scheme 1: Plausible reaction paths of the anodic oxidation of 1i in Et4NF·4HF/CH2Cl2.
Scheme 2: Anodic fluorination of 1k.
Scheme 3: Anodic fluorination of cyclic derivative 1l.
Scheme 4: Anodic oxidation of 1m and 1n in Et4NF·4HF/CH2Cl2.
Scheme 5: General reaction mechanism for the anodic fluorination of 1.
Scheme 6: Reaction mechanism for the anodic oxidation of carboxylic acids 1m and 1n in the presence of a fluo...
Aminomethylation/hydrogenolysis as an alternative to direct methylation of metalated isoquinolines – a novel total synthesis of the alkaloid 7-hydroxy-6-methoxy-1-methylisoquinoline
- Benedikt C. Melzer,
- Jan G. Felber and
- Franz Bracher
Beilstein J. Org. Chem. 2018, 14, 130–134, doi:10.3762/bjoc.14.8
- naphthalene-derived natural product plumbagin. In fact, trapping 1-metalated isoquinoline 3 with Eschenmoser’s salt gave the aminomethyl derivative 5 in 37% yield. Chromatographic separation from starting material 3 (recovered yield: 32%) was unproblematic. Surprising results were obtained in our
Graphical Abstract
Figure 1: Previously published total syntheses of alkaloid 1 [11,12].
Scheme 1: Total synthesis of alkaloid 1 via direct ring metalation and methylation.
Scheme 2: Total synthesis of alkaloid 1 via the aminomethyl intermediate 5 and selectivity’s found in debenzy...
Fluorescent nucleobase analogues for base–base FRET in nucleic acids: synthesis, photophysics and applications
- Mattias Bood,
- Sangamesh Sarangamath,
- Moa S. Wranne,
- Morten Grøtli and
- L. Marcus Wilhelmsson
Beilstein J. Org. Chem. 2018, 14, 114–129, doi:10.3762/bjoc.14.7
- ). Notable recent examples of fluorescent base analogues. For cnA and dnA the attachment point to the substituted naphthalene moiety has been varied. Absorption and emission of tC (dashed line) and tCO (solid line) in dsDNA. The absorption below 300 nm is divided by three to emphasize the absorption spectral
Graphical Abstract
Figure 1: a) Angles and unit vectors used to define the relative orientations of the donor and acceptor trans...
Figure 2: Notable recent examples of fluorescent base analogues. For cnA and dnA the attachment point to the ...
Scheme 1: Synthesis of the tricyclic cytosine aromatic core [39]. (a) Ethylene glycol, K2CO3, 120 °C, 1 h, 40%; (...
Scheme 2: Synthesis of protected tC and tCO deoxyribose phosphonates [41]. (a) Ac2O, pyridine, rt; (b) 2-mesityle...
Scheme 3: Synthesis of protected tCnitro deoxyribose phosphoramidite [14]. a) aq NaOH, 24 h, reflux; b) EtOH, HCl...
Scheme 4: Improved synthesis of tC and tC derivatives, where R = H, 7-MeO or 8-MeO [47]. a) H2NNH2 followed by H2O...
Scheme 5: Improved synthesis of tCO derivatives [47]. a) Ac2O, pyridine, 16 h, rt, 85%; b) PPh3, CCl4, DCM, 5 h, ...
Scheme 6: Synthesis of protected tCO ribose phosphoramidite [50]. a) MesSO2Cl, DIPEA, MeCN, 4 h, rt; b) 2-aminoph...
Scheme 7: Synthesis of protected deoxyribose qA [51]. a) N-(tert-Butoxycarbonyl)-2-(trimethylstannyl)aniline, (Ph3...
Scheme 8: Synthesis of protected deoxyribose qA for DNA SPS [53]. a) AcCl, MeOH, rt, 40 min; b) p-toluoyl chlorid...
Scheme 9: Synthesis of qA derivatives. a) EtI, Cs2CO3, DMF, 4 h, rt, 90%; b) HBPin, Pd(PPh3)4, Et3N, 1,4-diox...
Scheme 10: Synthesis of quadracyclic adenine base–base FRET pair. a) HCHO, NaOH, MeCN, H2O, 50 °C, 1 h; b) TBD...
Figure 3: Absorption and emission of tC (dashed line) and tCO (solid line) in dsDNA. The absorption below 300...
Figure 4: Spectral overlap between the emission of qAN1 (cyan) and the absorption of qAnitro (black) in dsDNA...
Figure 5: Example of typical FRET efficiency as a function of number of base pairs separating the donor and a...
Figure 6: FRET efficiency as a function of number of base pairs separating the donor (qAN1) and acceptor (qAn...
Synthesis and supramolecular properties of regioisomers of mononaphthylallyl derivatives of γ-cyclodextrin
- Markéta Bláhová,
- Sergey K. Filippov,
- Lubomír Kováčik,
- Jiří Horský,
- Simona Hybelbauerová,
- Zdenka Syrová,
- Tomáš Křížek and
- Jindřich Jindřich
Beilstein J. Org. Chem. 2017, 13, 2509–2520, doi:10.3762/bjoc.13.248
- complexation of the alkylation agent to the CD cavity and orientation of the agent´s reactive center towards the 3-OH group [11][12][13]. Here, we report the preparation of regioisomers of novel mononaphthylallyl γ-CD (NA-CD), i.e., 3-(naphthalene-2-yl)prop-2-en-1-yl γ-CD, which is interesting for several
- based on a direct alkylation of γ-CD with 2-(3-chloroprop-1-enyl)naphthalene. Cross-metathesis Mono 2I-O-, 3I-O- and 6I-O-naphthylallyl-γ-CDs (2-O-NA-γ-CD, 2a, 3-O-NA-γ-CD, 2b, 6-O-NA-γ-CD, 2c) were prepared from peracetylated O-allyl derivatives [14] by cross-metathesis with 2-vinylnaphthalene (Scheme
- allyl esters was described before by Tanaka et al. [26][27]. Naphthylallylation The same naphthylallyl derivatives of γ-CD 2a–c were also prepared by direct alkylation of γ-CD with 2-(3-chloroprop-1-enyl)naphthalene [28] as the alkylation reagent (Scheme 2). This reagent is easy to prepare on a large
Graphical Abstract
Scheme 1: Preparation of 2I-O-, 3I-O- and 6I-O-naphthylallyl derivatives of γ-CD by cross-metathesis.
Scheme 2: Preparation of 2-O-, 3-O- and 6-O-NA derivatives of γ-CD by direct alkylation (see Table 1 for the yields ...
Figure 1: Volume-weighted distribution functions for water solutions of 2-O- (2a), 3-O- (2b), and 6-O- (2c) N...
Figure 2: Distribution functions for 2-O- (2a), 3-O- (2b), and 6-O- (2c) NA-γ-CD regioisomers in 50% MeOH (v/...
Figure 3: Volume-weighted distribution functions for the 3-O- (2b) and 6-O- (2c) NA-γ-CD regioisomer at diffe...
Figure 4: Effect of increasing concentration and sonication on the morphology of the 3-O-derivative 2b. A to ...
Figure 5: Effect of increasing concentration and sonication on the morphology of the 2-O-derivative 2a. A: 2 ...
Figure 6: Effect of increasing concentration and sonication on the morphology of the 6-O-derivative 2c. A: 0....
Figure 7: Heat change for injection per mole of NA-γ-CD added as a function of the total concentration of NA-...
Figure 8: 1H NMR spectra of 2-O-derivative 2a in D2O at concentrations of 100, 10, and 1 mM.
Figure 9: 1H NMR spectra of 3-O-derivative 2b in D2O at concentrations of 100, 10, and 1 mM.
Figure 10: Putative objects and interactions in naphthylallyl-γ-CD solution, depicted schematically for 6I-O-n...
One-pot syntheses of blue-luminescent 4-aryl-1H-benzo[f]isoindole-1,3(2H)-diones by T3P® activation of 3-arylpropiolic acids
- Melanie Denißen,
- Alexander Kraus,
- Guido J. Reiss and
- Thomas J. J. Müller
Beilstein J. Org. Chem. 2017, 13, 2340–2351, doi:10.3762/bjoc.13.231
- are often prepared by condensation of acid anhydrides and amines [34]. Their applications are widespread, ranging from pharmaceutically active compounds [35] to agrochemicals [36] and fluorophores [37]. The characteristic photophysical properties of 1,8- and 2,3-naphthalene imides render the substance
- can be detected and monitored by absorption and emission spectroscopy. Furthermore, the investigation of a substance library of various 2,3- and 1,8-naphthalene imides has shown that the electronic nature of the ground and the excited state is decisively influenced by variation of the substitution
- pattern of the naphthalene scaffold. Even the smallest polarity change in the solvent system effects their absorption and emission behavior [34][40]. Very recent investigations on naphthaleneimide derivatives revealed enormous phosphorescence lifetimes that are particularly interesting for imaging
Graphical Abstract
Scheme 1: Mechanistic rationale and optimization of the domino synthesis of 4-arylnaphtho[2,3-c]furan-1,3-dio...
Scheme 2: Domino synthesis of 4-arylnaphtho[2,3-c]furan-1,3-diones 2 via in situ activation of arylpropiolic ...
Scheme 3: Optimization of the synthesis of 2,4-diphenyl-1H-benzo[f]isoindole-1,3(2H)-dione (4a) by imidation ...
Scheme 4: Pseudo three-component synthesis of 4-aryl-1H-benzo[f]isoindole-1,3(2H)-diones 4.
Scheme 5: Modified sequence for the synthesis of acceptor-substituted 4-aryl-1H-benzo[f]isoindole-1,3(2H)-dio...
Figure 1: The ORTEP-style plot of crystal structure 4b (ellipsoids are draw at the 40% probability level).
Scheme 6: Pseudo four-component synthesis of (E)-2,9-diphenyl-3-(phenylimino)-2,3-dihydro-1H-benzo[f]isoindol...
Scheme 7: Synthesis of 6-phenyl-12H-benzo[f]benzo[4,5]imidazo[2,1-a]isoindol-12-one (6).
Figure 2: The ORTEP-type plot of the crystal structure 5 (left) and a centrosymmetric dimer formation by π–π ...
Figure 3: The ORTEP-type plot of the asymmetric unit of the crystal structure 6 (top) and π-stacking interact...
Figure 4: Emission properties of compounds 4a,b,d–f, 5, and 6 under handheld UV-lamp (λexc ≈ 350 nm).
Figure 5: Relative emission intensities of compounds 4a,b,d–f (recorded in CH2Cl2 UVASOL® at T = 293 K; λexc ...
Figure 6: Absorption and emission properties of selected imides 4 measured in CH2Cl2 UVASOL® at 293 K with λe...
Figure 7: Hammett–Taft correlations of the emission maxima (red circles, lmax,em = 4274 · sR + 24495 [cm−1], R...
Figure 8: Relative emission intensities of the 1-phenyl-2,3-naphthaleneimide 4a (blue) and the pentacyclus 6 ...
An efficient Pd–NHC catalyst system in situ generated from Na2PdCl4 and PEG-functionalized imidazolium salts for Mizoroki–Heck reactions in water
- Nan Sun,
- Meng Chen,
- Liqun Jin,
- Wei Zhao,
- Baoxiang Hu,
- Zhenlu Shen and
- Xinquan Hu
Beilstein J. Org. Chem. 2017, 13, 1735–1744, doi:10.3762/bjoc.13.168
- -PEG1900-Im was heated with various organic bromides (2-(bromomethyl)pyridine, benzyl bromide and 1-(bromomethyl)naphthalene) to generate the corresponding imidazolium salts L1–L3 under solvent-free conditions. All imidazolium salts were water-soluble and air-stable. The resulted salts L1–L3 were
Graphical Abstract
Figure 1: Structures of imidazolium salts L1–L3.
Scheme 1: The synthetic route for the preparation of imidazolium salts L1–L3.
Figure 2: Kinetic profiles of Mizoroki–Heck reactions in water, Na2PdCl4/L1 (square), L2 (circle), and L3 (tr...
Figure 3: Reusability of the Na2PdCl4/L1 catalytic system for the catalytic Mizoroki–Heck coupling reaction o...
The chemistry and biology of mycolactones
- Matthias Gehringer and
- Karl-Heinz Altmann
Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159
Graphical Abstract
Figure 1: Initial proposal for the core macrolactone structure (left) and the established complete structure ...
Figure 2: Mycolactone congeners and their origins.
Figure 3: Misassigned mycolactone E structure according to Small et al. [50] (11) and the correct structure (6) f...
Figure 4: Schematic illustration of Kishi’s improved mycolactone TLC detection method exploiting derivatizati...
Figure 5: Fluorescent probes derived from natural mycolactone A/B (1a,b) or its synthetic 8-desmethyl analogs...
Figure 6: Tool compounds used by Pluschke and co-workers for elucidating the molecular targets of mycolactone...
Figure 7: Synthetic strategies towards the extended mycolactone core. A) General strategies. B) Kishi’s appro...
Scheme 1: Kishi’s 1st generation approach towards the extended core structure of mycolactones. Reagents and c...
Scheme 2: Kishi’s 2nd generation approach towards the extended core structure of mycolactones. Reagents and c...
Scheme 3: Kishi’s 3rd generation approach towards the extended core structure of mycolactones. Reagents and c...
Scheme 4: Negishi’s synthesis of the extended core structure of mycolactones. Reagents and conditions: a) (i) ...
Scheme 5: Burkart’s (incomplete) 1st generation approach towards the extended core structure of mycolactones....
Scheme 6: Burkart’s (incomplete) 1st, 2nd and 3rd generation approach towards the extended mycolactone core s...
Scheme 7: Altmann’s synthesis of alkyl iodide 91. Reagents and conditions: a) (i) PMB-trichloroacetimidate, T...
Scheme 8: Final steps of Altmann’s synthesis of the extended core structure of mycolactones. Reagents and con...
Scheme 9: Basic principles of the Aggarwal lithiation–borylation homologation process [185,186].
Scheme 10: Aggarwal’s synthesis of the C1–C11 fragment of the mycolactone core. Reagents and conditions: a) Cl...
Scheme 11: Aggarwal’s synthesis of the linear C1–C20 fragment of the mycolactone core. Reagents and conditions...
Figure 8: Synthetic strategies towards the mycolactone A/B lower side chain.
Scheme 12: Gurjar and Cherian’s synthesis of the C1’–C8’ fragment of the mycolactone A/B pentaenoate side chai...
Scheme 13: Gurjar and Cherian’s synthesis of the benzyl-protected mycolactone A/B pentaenoate side chain. Reag...
Scheme 14: Kishi’s synthesis of model compounds for elucidating the stereochemistry of the C7’–C16’ fragment o...
Scheme 15: Kishi’s synthesis of the mycolactone A/B pentaenoate side chain. (a) (i) NaH, (EtO)2P(O)CH2CO2Et, T...
Scheme 16: Feringa and Minnaard's incomplete synthesis of mycolactone A/B pentaenoate side chain. Reagents and...
Scheme 17: Altmann’s approach towards the mycolactone A/B pentaenoate side chain. Reagents and conditions: a) ...
Scheme 18: Negishi’s access to the C1’–C7’ fragment of mycolactone A. Reagents and conditions: a) (i) n-BuLi, ...
Scheme 19: Negishi’s approach to the C1’–C7’ fragment of mycolactone B. Reagents and conditions: a) (i) DIBAL-...
Scheme 20: Negishi’s synthesis of the C8’–C16’ fragment of mycolactone A/B. Reagents and conditions: a) 142, BF...
Scheme 21: Negishi’s assembly of the mycolactone A and B pentaenoate side chains. Reagents and conditions: a) ...
Scheme 22: Blanchard’s approach to the mycolactone A/B pentaenoate side chain. a) (i) Ph3P=C(Me)COOEt, CH2Cl2,...
Scheme 23: Kishi’s approach to the mycolactone C pentaenoate side chain exemplified for the 13’R,15’S-isomer 1...
Scheme 24: Altmann’s (unpublished) synthesis of the mycolactone C pentaenoate side chain. Reagents and conditi...
Scheme 25: Blanchard’s synthesis of the mycolactone C pentaenoate side chain. Reagents and conditions: a) (i) ...
Scheme 26: Kishi’s synthesis of the tetraenoate side chain of mycolactone F exemplified by enantiomer 165. Rea...
Scheme 27: Kishi’s synthesis of the mycolactone E tetraenoate side chain. Reagents and conditions: a) (i) CH2=...
Scheme 28: Wang and Dai’s synthesis of the mycolactone E tetraenoate side chain. Reagents and conditions: a) (...
Scheme 29: Kishi’s synthesis of the dithiane-protected tetraenoate side chain of the minor oxo-metabolite of m...
Scheme 30: Kishi’s synthesis of the mycolactone S1 and S2 pentaenoate side chains. Reagents and conditions: a)...
Scheme 31: Kishi’s 1st generation and Altmann’s total synthesis of mycolactone A/B (1a,b) and Negishi’s select...
Scheme 32: Kishi’s 2nd generation total synthesis of mycolactone A/B (1a,b). Reagents and conditions: a) 2,4,6...
Scheme 33: Blanchard’s synthesis of the 8-desmethylmycolactone core. Reagents and conditions: a) (i) TsCl, TEA...
Scheme 34: Altmann’s (partially unpublished) synthesis of the C20-hydroxylated mycolactone core. Reagents and ...
Scheme 35: Altmann’s and Blanchard’s approaches towards the 11-isopropyl-8-desmethylmycolactone core. Reagents...
Scheme 36: Blanchard’s synthesis of the saturated variant of the C11-isopropyl-8-desmethylmycolactone core. Re...
Scheme 37: Structure elucidation of photo-mycolactones generated from tetraenoate 224.
Scheme 38: Kishi’s synthesis of the linear precursor of the photo-mycolactone B1 lower side chain. Reagents an...
Scheme 39: Kishi’s synthesis of the photo-mycolactone B1 lower side chain. Reagents and conditions: a) LiTMP, ...
Scheme 40: Kishi’s synthesis of a stabilized lower mycolactone side chain. Reagents and conditions: a) (i) TBD...
Scheme 41: Blanchard’s variation of the C12’,C13’,C15’ stereocluster. Reagents and conditions: a) (i) DIBAL-H,...
Scheme 42: Blanchard’s synthesis of aromatic mycolactone polyenoate side chain analogs. Reagents and condition...
Scheme 43: Small’s partial synthesis of a BODIPY-labeled mycolactone derivative and Demangel’s partial synthes...
Scheme 44: Blanchard’s synthesis of the BODIPY-labeled 8-desmethylmycolactones. Reagents and conditions: a) (i...
Scheme 45: Altmann’s synthesis of biotinylated mycolactones. Reagents and conditions: a) (i) CDI, THF, rt, 2 d...
Figure 9: Kishi’s elongated n-butyl carbamoyl mycolactone A/B analog.
A novel approach to oxoisoaporphine alkaloids via regioselective metalation of alkoxy isoquinolines
- Benedikt C. Melzer and
- Franz Bracher
Beilstein J. Org. Chem. 2017, 13, 1564–1571, doi:10.3762/bjoc.13.156
- pyridine nitrogen), can very well promote a directed remote metalation. To test our hypothesis, we performed two more D2O quenching experiments with naphthalene analogues of esters 10 and amide 12. The methyl ester analogue 15 was obtained by Suzuki cross-coupling of naphthalene-1-boronic acid (13) and
- only in the ortho-position to the benzamide residue (C-2 of the naphthalene ring system), but not in the peri-position (C-8 of the naphthalene). Consequently, further attempts to initialize the cyclization of arylisoquinolines 10c and 12 to the oxoisoaporphine alkaloid bianfugecine (6, Scheme 5) by a
Graphical Abstract
Figure 1: Prominent oxoaporphine and oxoisoaporphine alkaloids: liriodenine (1), menisporphine (2), dauriporp...
Scheme 1: Previously reported [7,17] and new approach to oxoisoaporphine alkaloids.
Scheme 2: Synthesis of iodinated isoquinolines 8a–c from alkoxy-substituted isoquinolines 7a–c.
Scheme 3: Synthesis of methyl 2-(isoquinolin-1-yl)benzoates 10a–c from 1-iodoisoquinolines 8a–c.
Scheme 4: Synthesis of the alkaloids 6-O-demethylmenisporphine (4), dauriporphinoline (5), and bianfugecine (6...
Scheme 5: Attempted synthesis of bianfugecine (6) via directed remote metalation and subsequent trapping of t...
Scheme 6: Outcome of a D2O quenching experiment after metalation of amide 12.
Scheme 7: Synthesis of 1-arylnaphthalene analogues 15 and 16.
Scheme 8: Outcome of a D2O quenching experiment after metalation of amide 16 with LDA.
Scheme 9: Synthesis of the alkaloids menisporphine (2) and dauriporphine (3) by O-methylation of the alkaloid...
Synthesis of 1-indanones with a broad range of biological activity
- Marika Turek,
- Dorota Szczęsna,
- Marek Koprowski and
- Piotr Bałczewski
Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48
Graphical Abstract
Figure 1: Biologically active 1-indanones and their structural analogues.
Figure 2: Number of papers about (a) 1-indanones, (b) synthesis of 1-indanones.
Scheme 1: Synthesis of 1-indanone (2) from hydrocinnamic acid (1).
Scheme 2: Synthesis of 1-indanone (2) from 3-(2-bromophenyl)propionic acid (3).
Scheme 3: Synthesis of 1-indanones 5 from 3-arylpropionic acids 4.
Scheme 4: Synthesis of kinamycin (9a) and methylkinamycin C (9b).
Scheme 5: Synthesis of trifluoromethyl-substituted arylpropionic acids 12, 1-indanones 13 and dihydrocoumarin...
Scheme 6: Synthesis of 1-indanones 16 from benzoic acids 15.
Scheme 7: Synthesis of 1-indanones 18 from arylpropionic and 3-arylacrylic acids 17.
Scheme 8: The NbCl5-induced one-step synthesis of 1-indanones 22.
Scheme 9: Synthesis of biologically active 1-indanone derivatives 26.
Scheme 10: Synthesis of enantiomerically pure indatraline ((−)-29).
Scheme 11: Synthesis of 1-indanone (2) from the acyl chloride 30.
Scheme 12: Synthesis of the mechanism-based inhibitors 33 of coelenterazine.
Scheme 13: Synthesis of the indane 2-imidazole derivative 37.
Scheme 14: Synthesis of fluorinated PAHs 41.
Scheme 15: Synthesis of 1-indanones 43 via transition metal complexes-catalyzed carbonylative cyclization of m...
Scheme 16: Synthesis of 6-methyl-1-indanone (46).
Scheme 17: Synthesis of 1-indanone (2) from ester 48.
Scheme 18: Synthesis of benzopyronaphthoquinone 51 from the spiro-1-indanone 50.
Scheme 19: Synthesis of the selective endothelin A receptor antagonist 55.
Scheme 20: Synthesis of 1-indanones 60 from methyl vinyl ketone (57).
Scheme 21: Synthesis of 1-indanones 64 from diethyl phthalate 61.
Scheme 22: Synthesis of 1-indanone derivatives 66 from various Meldrum’s acids 65.
Scheme 23: Synthesis of halo 1-indanones 69.
Scheme 24: Synthesis of substituted 1-indanones 71.
Scheme 25: Synthesis of spiro- and fused 1-indanones 73 and 74.
Scheme 26: Synthesis of spiro-1,3-indanodiones 77.
Scheme 27: Mechanistic pathway for the NHC-catalyzed Stetter–Aldol–Michael reaction.
Scheme 28: Synthesis of 2-benzylidene-1-indanone derivatives 88a–d.
Scheme 29: Synthesis of 1-indanone derivatives 90a–i.
Scheme 30: Synthesis of 1-indanones 96 from o-bromobenzaldehydes 93 and alkynes 94.
Scheme 31: Synthesis of 3-hydroxy-1-indanones 99.
Scheme 32: Photochemical preparation of 1-indanones 103 from ketones 100.
Scheme 33: Synthesis of chiral 3-aryl-1-indanones 107.
Scheme 34: Photochemical isomerization of 2-methylbenzil 108.
Scheme 35: Synthesis of 2-hydroxy-1-indanones 111a–c.
Scheme 36: Synthesis of 1-indanone derivatives 113 and 114 from η6-1,2-dioxobenzocyclobutene complex 112.
Scheme 37: Synthesis of nakiterpiosin (117).
Scheme 38: Synthesis of 2-alkyl-1-indanones 120.
Scheme 39: Synthesis of fluorine-containing 1-indanone derivatives 123.
Scheme 40: Synthesis of 2-benzylidene and 2-benzyl-1-indanones 126, 127 from the chalcone 124.
Scheme 41: Synthesis of 2-bromo-6-methoxy-3-phenyl-1-indanone (130).
Scheme 42: Synthesis of combretastatin A-4-like indanones 132a–s.
Figure 3: Chemical structures of investigated dienones 133 and synthesized cyclic products 134–137.
Figure 4: Chemical structures of 1-indanones and their heteroatom analogues 138–142.
Scheme 43: Synthesis of 2-phosphorylated and 2-non-phosphorylated 1-indanones 147 and 148 from β-ketophosphona...
Scheme 44: Photochemical synthesis of 1-indanone derivatives 150, 153a, 153b.
Scheme 45: Synthesis of polysubstituted-1-indanones 155, 157.
Scheme 46: Synthesis of 1-indanones 159a–g from α-arylpropargyl alcohols 158 using RhCl(PPh3)3 as a catalyst.
Scheme 47: Synthesis of optically active 1-indanones 162 via the asymmetric Rh-catalyzed isomerization of race...
Scheme 48: Mechanism of the Rh-catalyzed isomerization of α-arylpropargyl alcohols 161 to 1-indanones 162.
Figure 5: Chemical structure of abicoviromycin (168) and its new benzo derivative 169.
Scheme 49: Synthesis of racemic benzoabicoviromycin 172.
Scheme 50: Synthesis of [14C]indene 176.
Scheme 51: Synthesis of indanone derivatives 178–180.
Scheme 52: Synthesis of racemic pterosin A 186.
Scheme 53: Synthesis of trans-2,3-disubstituted 1-indanones 189.
Scheme 54: Synthesis of 3-aryl-1-indanone derivatives 192.
Scheme 55: Synthesis of 1-indanone derivatives 194 from 3-(2-iodoaryl)propanonitriles 193.
Scheme 56: Synthesis of 1-indanones 200–204 by cyclization of aromatic nitriles.
Scheme 57: Synthesis of 1,1’-spirobi[indan-3,3’-dione] derivative 208.
Scheme 58: Total synthesis of atipamezole analogues 211.
Scheme 59: Synthesis of 3-[4-(1-piperidinoethoxy)phenyl]spiro[indene-1,1’-indan]-5,5’-diol hydrochloride 216.
Scheme 60: Synthesis of 3-arylindan-1-ones 219.
Scheme 61: Synthesis of 2-hydroxy-1-indanones 222.
Scheme 62: Synthesis of the 1-indanone 224 from the THP/MOM protected chalcone epoxide 223.
Scheme 63: Synthesis of 1-indanones 227 from γ,δ-epoxy ketones 226.
Scheme 64: Synthesis of 2-hydroxy-2-methylindanone (230).
Scheme 65: Synthesis of 1-indanone derivatives 234 from cyclopropanol derivatives 233.
Scheme 66: Synthesis of substituted 1-indanone derivatives 237.
Scheme 67: Synthesis of 7-methyl substituted 1-indanone 241 from 1,3-pentadiene (238) and 2-cyclopentenone (239...
Scheme 68: Synthesis of disubstituted 1-indanone 246 from the siloxydiene 244 and 2-cyclopentenone 239.
Scheme 69: Synthesis of 5-hydroxy-1-indanone (250) via the Diels–Alder reaction of 1,3-diene 248 with sulfoxid...
Scheme 70: Synthesis of halogenated 1-indanones 253a and 253b.
Scheme 71: Synthesis of 1-indanones 257 and 258 from 2-bromocyclopentenones 254.
Scheme 72: Synthesis of 1-indanone 261 from 2-bromo-4-acetoxy-2-cyclopenten-1-one (260) and 1,2-dihydro-4-viny...
Scheme 73: Synthesis of 1-indanone 265 from 1,2-dihydro-7-methoxy-4-vinylnaphthalene (262) and bromo-substitut...
Scheme 74: Synthesis of 1-indanone 268 from dihydro-3-vinylphenanthrene 266 and 4-acetoxy-2-cyclopenten-1-one (...
Scheme 75: Synthesis of 1-indanone 271 from phenylselenyl-substituted cyclopentenone 268.
Scheme 76: Synthesis of 1-indanone 272 from the trienone 270.
Scheme 77: Synthesis of the 1-indanone 276 from the aldehyde 273.
Scheme 78: Synthesis of 1-indanones 278 and 279.
Scheme 79: Synthesis of 1-indanone 285 from octa-1,7-diyne (282) and cyclopentenone 239.
Scheme 80: Synthesis of benz[f]indan-1-one (287) from cyclopentenone 239 and o-bis(dibromomethyl)benzene (286)....
Scheme 81: Synthesis of 3-methyl-substituted benz[f]indan-1-one 291 from o-bis(dibromomethyl)benzene (286) and...
Scheme 82: Synthesis of benz[f]indan-1-one (295) from the anthracene epidioxide 292.
Scheme 83: Synthesis of 1-indanone 299 from homophthalic anhydride 298 and cyclopentynone 297.
Scheme 84: Synthesis of cyano-substituted 1-indanone derivative 301 from 2-cyanomethylbenzaldehyde (300) and c...
Scheme 85: Synthesis of 1-indanone derivatives 303–305 from ketene dithioacetals 302.
Scheme 86: Synthesis of 1-indanones 309–316.
Scheme 87: Mechanism of the hexadehydro-Diels–Alder (HDDA) reaction.
Scheme 88: Synthesis of 1-indenone 318 and 1-indanones 320 and 321 from tetraynes 317 and 319.
Scheme 89: Synthesis of 1-indanone 320 from the triyn 319.
Scheme 90: Synthesis 1-indanone 328 from 2-methylfuran 324.
Scheme 91: Synthesis of 1-indanones 330 and 331 from furans 329.
Scheme 92: Synthesis of 1-indanone 333 from the cycloadduct 332.
Scheme 93: Synthesis of (S)-3-arylindan-1-ones 335.
Scheme 94: Synthesis of (R)-2-acetoxy-1-indanone 338.
Figure 6: Chemical structures of obtained cyclopenta[α]phenanthrenes 339.
Scheme 95: Synthesis of the benzoindanone 343 from arylacetaldehyde 340 with 1-trimethylsilyloxycyclopentene (...
Synthesis and optical properties of new 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles
- Anastasia S. Kostyuchenko,
- Tatyana Yu. Zheleznova,
- Anton J. Stasyuk,
- Aleksandra Kurowska,
- Wojciech Domagala,
- Adam Pron and
- Alexander S. Fisyuk
Beilstein J. Org. Chem. 2017, 13, 313–322, doi:10.3762/bjoc.13.34
- to the π–π* transition for the studied thiophene, phenyl, naphthalene and anthracene-substituted derivatives, shows a small hypsochromic shift with increasing spatial volume of the substituent R. This observation is in a full accordance with the aforementioned relationship of the molecule planarity
Graphical Abstract
Figure 1: D–A compounds 1–3.
Scheme 1: Synthesis of 3-decyl-2,2'-bithiophene-5-carboxylic acid ethyl esters 7a–c.
Scheme 2: Synthesis of ethyl esters of 5'-aryl-3-decyl-2,2'-bithiophene-5-carboxylic acids 7d–g.
Scheme 3: Synthesis of diacyl hydrazines 14b–g.
Scheme 4: Synthesis of 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles 15b–g.
Figure 2: 5'-Aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles 15b–g: a) absorption sp...
Figure 3: General structure of 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles.
Figure 4: Frontier molecular orbitals (HOMO−1, HOMO, LUMO and LUMO+1) and values for HOMO–LUMO band gaps of t...
A new class of organogelators based on triphenylmethyl derivatives of primary alcohols: hydrophobic interactions alone can mediate gelation
- Wangkhem P. Singh and
- Rajkumar S. Singh
Beilstein J. Org. Chem. 2017, 13, 138–149, doi:10.3762/bjoc.13.17
- ][24]. Similar is the case for π-stacking interaction (seen in naphthalene, anthracene, pyrene, perylene, etc.) which has been mostly used in combination with other types of secondary interactions in the discovery of many gelators [25][26]. This holds true for many other non-covalent interactions as
- interactions between the alkyl chains and the triphenylmethyl moieties. Compared to other planar aromatic molecules (such as naphthalene, anthracene, perylene, etc.), the triphenylmethyl moiety as a whole exhibits a non-planar geometry, hence π-stacking interaction between triphenylmethyl moieties may not be
Graphical Abstract
Scheme 1: Chemical structures of triphenylmethyl-based organogelators.
Figure 1: Organogels formed by TPM-G12 in (a) propan-1-ol; (b) DMSO at 0.5% w/v; (c) organogel from TPM-G5 in...
Figure 2: Plot of Tgel (gel–sol transition temperature) versus gelators at different concentrations. TPM-G12 ...
Figure 3: DSC thermograms of gels prepared from TPM-G12 in (a) Propan-1-ol and (b) DMSO.
Figure 4: SEM images of the dried gels. TPM-G12 in propan-1-ol (a) and (b), in DMSO (c) and (d); TPM-G5 in DM...
Figure 5: Stress sweep rheological experiment of TPM-G12 gel (1.5% w/v) in (a) propan-1-ol (b) DMSO.
Figure 6: FTIR spectra of gelator TPM-G12 in (a) CHCl3 and (b) xerogel in KBr.
Figure 7: Powder X-ray diffraction patterns of xerogel of (a) TPM-G12 from propan-1-ol and (b) TPM-G5 from DM...
Figure 8: Energy minimized conformational structure of (a) TPM-G12 and (b) TPM-G5 obtained using B3LYP/6-31G ...
Figure 9: Possible molecular packing arrangement in the self-assembled gel state of (a) TPM-G12 and (b) TPM-G5...
Figure 10: Time-dependent UV–vis absorption profile of (a) Direct Red 80 (b) Crystal Violet aqueous dye soluti...
cis-Diastereoselective synthesis of chroman-fused tetralins as B-ring-modified analogues of brazilin
- Dimpee Gogoi,
- Runjun Devi,
- Pallab Pahari,
- Bipul Sarma and
- Sajal Kumar Das
Beilstein J. Org. Chem. 2016, 12, 2816–2822, doi:10.3762/bjoc.12.280
- group of 5 and/or 9, leading to the formation of a stable 3°carbocation that can undergo further dehydration reactions until full aromatization to the naphthalene ring is achieved. This study would serve to help us to find the real scenario. Finally, in the presence of Lewis/Brønsted acids, substrates 6
Graphical Abstract
Figure 1: Chroman-based tetracyclic natural products 1–4 of the brazilin family and our designed, B-ring-modi...
Scheme 1: Retrosynthetic analysis of the designed B-ring-modified analogues of brazilin.
Scheme 2: The synthetic challenge associated with the synthesis of 5 by IFCEA of 6 (above) and recent literat...
Figure 2: Assessment of the IFCEA cyclization on additional substrates (±)-6b–n leading to (±)-5b–n. Reaction...
Figure 3: ORTEP diagram of 5k.
Scheme 3: Stereoselective conversion of (±)-5k into (±)-14.
