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Search for "furanone" in Full Text gives 15 result(s) in Beilstein Journal of Organic Chemistry.
Entry to new spiroheterocycles via tandem Rh(II)-catalyzed O–H insertion/base-promoted cyclization involving diazoarylidene succinimides
- Alexander Yanovich,
- Anastasia Vepreva,
- Ksenia Malkova,
- Grigory Kantin and
- Dmitry Dar’in
Beilstein J. Org. Chem. 2024, 20, 561–569, doi:10.3762/bjoc.20.48
- also in the alpha position of the furanone ring. Reactions with allenic acids 11 were carried out according to a similar scheme, in the one-pot mode, without isolation of OH-insertion intermediates 12 (Scheme 4). In order to accelerate the cyclization step in this case, moderate heating was used after
- of DIPEA (60 mol %), which can be explained by the presence of EDG in the corresponding DAS. In general, the second step of the process appears to occur as endo-cyclization onto an activated multiple bond followed by migration of the remaining endocyclic double bond into the furanone ring. The
Graphical Abstract
Scheme 1: DAS spirocyclizations reported earlier and the synthetic methodology investigated in this work.
Figure 1: Examples of biologically active compounds and natural products based on THF/THP spiro-conjugates wi...
Scheme 2: An initial example on Rh(II)-catalyzed O–H insertion/base-promoted cyclization involving diazo comp...
Scheme 3: Tandem Rh2(esp)2-catalyzed O–H insertion/base-promoted cyclization involving DAS 1 and various prop...
Scheme 4: Tandem Rh2(esp)2-catalyzed O–H insertion/base-promoted cyclization involving DAS 1 and allenic acid...
Scheme 5: Tandem Rh2(esp)2-catalyzed O–H insertion/base-promoted cyclization involving various DAS 1 and 3-br...
Scheme 6: Tandem Rh2(esp)2-catalyzed O–H insertion/base-promoted cyclization involving DAS 1 and 2-(bromometh...
Scheme 7: Examples where a target spirocyclic product was not observed.
Scheme 8: Plausible mechanism of the transformations studied.
Synthesis of sulfur karrikin bioisosteres as potential neuroprotectives
- Martin Pošta,
- Václav Zima,
- Lenka Poštová Slavětínská,
- Marika Matoušová and
- Petr Beier
Beilstein J. Org. Chem. 2022, 18, 549–554, doi:10.3762/bjoc.18.57
- concentrations [11][12][13][14]. Structurally, the karrikin backbone consists of a fused pyran and a furanone ring. Each particular molecule differs in the number of methyl groups in positions C3, C5 and C7. Structures of the four most active and abundant karrikins (KAR1–KAR4) are depicted in Figure 1. The
- synthesis of these heterocycles is rather challenging, because the fused pyran and furanone system cannot be easily prepared by standard cyclization methods [15][16][17]. Although karrikins are extremely active plant growth regulators [14][18][19], their biological activity in humans was not investigated
Graphical Abstract
Figure 1: Structures of naturally occurring karrikins.
Scheme 1: i) P4S10, THF; ii) 2-chloropropionyl chloride, Et3N; iii) Ph3P, NaOAc, Ac2O.
Figure 2: Target compounds with highlighted positions of oxygen to sulfur exchange.
Scheme 2: i) Lawesson’s reagent, HMDO, toluene, MW irradiation, 120 °C, 60 min.
Scheme 3: i) P4S10 or Lawesson’s reagent, see table for conditions; ii) 2-chloropropionyl chloride, Et3N, DCM...
Scheme 4: i) LiHMDS, MeI, THF, −78 °C.
Scheme 5: i) a) NaOH, MeOH/H2O, rt, Amberlyst 15 [H+], b) AcOH 70% aq, reflux, 2 h; ii) a) EtOCOCl, pyridine,...
Scheme 6: i) Lawesson’s reagent, HMDO, toluene, MW irradiation (120 °C), 60 min.
Menadione: a platform and a target to valuable compounds synthesis
- Acácio S. de Souza,
- Ruan Carlos B. Ribeiro,
- Dora C. S. Costa,
- Fernanda P. Pauli,
- David R. Pinho,
- Matheus G. de Moraes,
- Fernando de C. da Silva,
- Luana da S. M. Forezi and
- Vitor F. Ferreira
Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43
- ) triflate-catalyzed reaction showed the best results in terms of performance, producing furanone 56 in 65% yield. Additionally, this study was also extended to the synthesis of hetero-tetracyclic derivatives containing endocyclic nitrogen atoms. The best result was obtained using triene 57, and 2.0
Graphical Abstract
Figure 1: Natural bioactive naphthoquinones.
Figure 2: Chemical structures of vitamins K.
Figure 3: Redox cycle of menadione.
Scheme 1: Selected approaches for menadione synthesis using silver(I) as a catalyst.
Scheme 2: Methylation approaches for the preparation of menadione from 1,4-naphthoquinone using tert-butyl hy...
Scheme 3: Methylation approach of 1,4-naphthoquinone using i) rhodium complexes/methylboronic acid and ii) bi...
Scheme 4: Synthesis of menadione (10) from itaconic acid.
Scheme 5: Menadione synthesis via Diels–Alder reaction.
Scheme 6: Synthesis of menadione (10) using p-cresol as a synthetic precursor.
Scheme 7: Synthesis of menadione (10) via demethoxycarbonylating annulation of methyl methacrylate.
Scheme 8: Furan 34 used as a diene in a Diels–Alder reaction for the synthesis of menadione (10).
Scheme 9: o-Toluidine as a dienophile in a Diels–Alder reaction for the synthesis of menadione (10).
Scheme 10: Representation of electrochemical synthesis of menadione.
Figure 4: Reaction sites and reaction types of menadione as substrate.
Scheme 11: DBU-catalyzed epoxidation of menadione (10).
Scheme 12: Phase-transfer catalysis for the epoxidation of menadione.
Scheme 13: Menadione epoxidation using a hydroperoxide derived from (+)-norcamphor.
Scheme 14: Enantioselective Diels–Alder reaction for the synthesis of asymmetric quinone 50 catalyzed by a chi...
Scheme 15: Optimized reaction conditions for the synthesis of anthra[9,1-bc]pyranone.
Scheme 16: Synthesis of anthra[9,1-bc]furanone, anthra[9,1-bc]pyridine, and anthra[9,1-bc]pyrrole derivatives.
Scheme 17: Synthesis of derivatives employing protected trienes.
Scheme 18: Synthesis of cyclobutene derivatives of menadione.
Scheme 19: Menadione reduction reactions using sodium hydrosulfite.
Scheme 20: Green methodology for menadiol synthesis and pegylation.
Scheme 21: Menadione reduction by 5,6-O-isopropylidene-ʟ-ascorbic acid under UV light irradiation.
Scheme 22: Selected approaches of menadione hydroacetylation to diacetylated menadiol.
Scheme 23: Thiele–Winter reaction catalyzed by Bi(OTf)3.
Scheme 24: Carbonyl condensation of menadione using resorcinol and a hydrazone derivative.
Scheme 25: Condensation reaction of menadione with thiosemicarbazide.
Scheme 26: Condensation reaction of menadione with acylhydrazides.
Scheme 27: Menadione derivatives functionalized with organochalcogens.
Scheme 28: Synthesis of selenium-menadione conjugates derived from chloromethylated menadione 84.
Scheme 29: Menadione alkylation by the Kochi–Anderson method.
Scheme 30: Menadione alkylation by diacids.
Scheme 31: Menadione alkylation by heterocycles-substituted carboxylic acids.
Scheme 32: Menadione alkylation by bromoalkyl-substituted carboxylic acids.
Scheme 33: Menadione alkylation by complex carboxylic acids.
Scheme 34: Kochi–Anderson method variations for the menadione alkylation via oxidative decarboxylation of carb...
Scheme 35: Copper-catalyzed menadione alkylation via free radicals.
Scheme 36: Nickel-catalyzed menadione cyanoalkylation.
Scheme 37: Iron-catalyzed alkylation of menadione.
Scheme 38: Selected approaches to menadione alkylation.
Scheme 39: Menadione acylation by photo-Friedel–Crafts acylation reported by Waske and co-workers.
Scheme 40: Menadione acylation by Westwood procedure.
Scheme 41: Synthesis of 3-benzoylmenadione via metal-free TBAI/TBHP system.
Scheme 42: Michael-type addition of amines to menadione reported by Kallmayer.
Scheme 43: Synthesis of amino-menadione derivatives using polyalkylamines.
Scheme 44: Selected examples for the synthesis of different amino-substituted menadione derivatives.
Scheme 45: Selected examples of Michael-type addition of complex amines to menadione (10).
Scheme 46: Addition of different natural α-amino acids to menadione.
Scheme 47: Michael-type addition of amines to menadione using silica-supported perchloric acid.
Scheme 48: Indolylnaphthoquinone or indolylnaphthalene-1,4-diol synthesis reported by Yadav et al.
Scheme 49: Indolylnaphthoquinone synthesis reported by Tanoue and co-workers.
Scheme 50: Indolylnaphthoquinone synthesis from menadione by Escobeto-González and co-workers.
Scheme 51: Synthesis of menadione analogues functionalized with thiols.
Scheme 52: Synthesis of menadione-derived symmetrical derivatives through reaction with dithiols.
Scheme 53: Mercaptoalkyl acids as nucleophiles in Michael-type addition reaction to menadione.
Scheme 54: Reactions of menadione (10) with cysteine derivatives for the synthesis of quinoproteins.
Scheme 55: Synthesis of menadione-glutathione conjugate 152 by Michael-type addition.
Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors
- Emine Kayahan,
- Mathias Jacobs,
- Leen Braeken,
- Leen C.J. Thomassen,
- Simon Kuhn,
- Tom van Gerven and
- M. Enis Leblebici
Beilstein J. Org. Chem. 2020, 16, 2484–2504, doi:10.3762/bjoc.16.202
- with a length of 11.5 m and an inner diameter of 0.8 mm were wrapped around two Pyrex® glass columns. UV lamps were placed inside the glass columns. A representative setup is given in Figure 3a. The addition of isopropanol to 2(5H)-furanone in the presence of the photosensitizer 4,4’-dimethoxy
Graphical Abstract
Figure 1: The momentum transport affects the mass transfer and the light field. All transport phenomena need ...
Figure 2: Common photomicroreactor designs: (a) Straight channel, (b) serpentine channel, (c) square serpenti...
Figure 3: Benchmarked photoreactors: (a) Microcapillaries in parallel, (b) microcapillaries in series, (c) fl...
Figure 4: Photochemical reactions that are detailed in Table 1.
Figure 5: Structured reactors designed for enhancing the mass transfer: (a) Packed bed photoreactor, (b) mono...
Figure 6: Comparison of the LED board designs of photomicroreactors: (a) CC array design, (b) MC array design...
Figure 7: Illustration of the light scattering phenomenon inside a photocatalytic flow reactor.
Figure 8: Efficiency of the absorption process in scattering situations with respect to pure absorption situa...
Figure 9: Different types of distributors: (a) Traditional or consecutive manifold, (b) bifurcation unit dist...
Ultrasonic-assisted unusual four-component synthesis of 7-azolylamino-4,5,6,7-tetrahydroazolo[1,5-a]pyrimidines
- Yana I. Sakhno,
- Maryna V. Murlykina,
- Oleksandr I. Zbruyev,
- Anton V. Kozyryev,
- Svetlana V. Shishkina,
- Dmytro Sysoiev,
- Vladimir I. Musatov,
- Sergey M. Desenko and
- Valentyn A. Chebanov
Beilstein J. Org. Chem. 2020, 16, 281–289, doi:10.3762/bjoc.16.27
- enabled us to develop highly selective procedures for obtaining triazolo-, tetrazolo-, and pyrazolopyrimidines [4][5][16][17][18][19][20][27][28][29], as well as oxygen-bridged tetrahydropyrazolopyrimidines [4][19], furanone [17][30], and pyrrolone derivatives [5][16][17][18]. Besides the presence of an
Graphical Abstract
Scheme 1: Synthesis of tetrahydroazolopyrimidine derivatives.
Scheme 2: Various multicomponent reactions involving pyruvic acids (pyruvates) and different α-aminoazoles.
Scheme 3: Synthesis of 4-arylamino-substituted tetrahydroquinolines.
Scheme 4: Ultrasound-assisted multicomponent reactions of 3-amino-1,2,4-triazole or 5-amino-1H-pyrazole-4-car...
Scheme 5: Synthesis of 3-cyano-7-(4-methoxyphenyl)-4,7-dihydropyrazolo[1,5-a]pyrimidine-5-carboxylic acid (7)....
Scheme 6: Proposed reaction mechanism.
Figure 1: Alternative structures A and B for the tetrahydroazolopyrimidines 4.
Figure 2: Molecular structure of ethyl 5-(4-bromophenyl)-3-cyano-7-((4-cyano-1H-pyrazol-5-yl)amino)-4,5,6,7-t...
Figure 3: Chains of 4g molecules in the crystal phase.
Natural products from microbes associated with insects
- Christine Beemelmanns,
- Huijuan Guo,
- Maja Rischer and
- Michael Poulsen
Beilstein J. Org. Chem. 2016, 12, 314–327, doi:10.3762/bjoc.12.34
- )), sesquiterpenes with an unprecedented carbon skeleton that are most likely built up by an enzymatic Aldol addition. In a similar example, new cytotoxic furanone analogues (e.g., paraconfuranone A (39)) were obtained from the fungus Paraconiothyrium brasiliense isolated from the gut of the grasshopper Acrida
Graphical Abstract
Figure 1: Flow chart of the typical characterization of chemical signals from microbial interactions. (1) Che...
Figure 2: Multilateral microbe–insect interactions. (1) Insect–symbiont interactions with both partners benef...
Figure 3: a) Interactions between bacterial (endo)symbionts and insects with both partners benefiting from th...
Figure 4: Multilateral microbial interactions in fungus-growing insects. (1) Insect cultivar: protects and sh...
Figure 5: Small molecules (chemical mediators) play key roles in maintaining garden homeostasis in fungus-gro...
Figure 6: Secondary metabolites isolated from Actinobacteria from fungus-growing termites. Microtermolide A (...
Figure 7: Secondary metabolites from bacterial mutualists of solitary insects. Bafilomycin A1 (21), bafilomyc...
Figure 8: Beneficial interactions (1) between fungal symbionts and insects.
Figure 9: Secondary metabolites isolated from fungal symbionts. Cerulenin (30), helvolic acid (31), lepiochlo...
Figure 10: Predatory interactions, (1) entomopathogenic fungi use insect as prey.
Figure 11: Entomopathogenic fungi use secondary metabolites as insecticidal compounds to kill their prey. Dest...
Recent applications of ring-rearrangement metathesis in organic synthesis
- Sambasivarao Kotha,
- Milind Meshram,
- Priti Khedkar,
- Shaibal Banerjee and
- Deepak Deodhar
Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199
- the fruiting body of P. igniarius, is a well-known anticancer agent. To assemble the spiro-fused furanone core of phelligridin G, Wright and Cooper [55] have used a RRM process as a key step. Wittig olefination of furylbenzaldehyde derivative 265 using methyltriphenylphosphonium bromide in the
- pyran derivatives. RRM of various functionalized oxanorbornene systems. RRM to assemble the spiro fused-furanone core unit. (i) 129, benzene, 55 °C, 3 days; (ii) Ph3P=CH2Br, n-BuLi, THF, 0 °C; (iii) 129, benzene, 40 °C, 24 h; (iv) catalyst 2 (10 mol %), CH2Cl2, 35 °C. RRM protocol to norbornenyl sultam
Graphical Abstract
Figure 1: Ruthenium alkylidene catalysts used in RRM processes.
Figure 2: General representation of various RRM processes.
Figure 3: A general mechanism for RRM process.
Scheme 1: RRM of cyclopropene systems.
Scheme 2: RRM of cyclopropene with catalyst 2. (i) catalyst 2 (2.5 mol %), ethylene (24, 1 atm), (ii) toluene...
Scheme 3: RRM of various cyclopropene derivatives with catalyst 2. (i) catalyst 2 (2.5 mol %), CH2Cl2 (c = 0....
Scheme 4: RRM of substituted cyclopropene system with catalyst 2.
Scheme 5: RRM of cyclobutene system with catalyst 2.
Scheme 6: RRM approach to various bicyclic compounds.
Scheme 7: RRM approach to erythrina alkaloid framework.
Scheme 8: ROM–RCM sequence to lactone derivatives.
Scheme 9: RRM protocol towards the synthesis of lactone derivative 58.
Scheme 10: RRM protocol towards the asymmetric synthesis of asteriscunolide D (61).
Scheme 11: RRM strategy towards the synthesis of various macrolide rings.
Scheme 12: RRM protocol to dipiperidine system.
Scheme 13: RRM of cyclopentene system to generate the cyclohexene systems.
Scheme 14: RRM of cyclopentene system 74.
Scheme 15: RRM approach to compound 79.
Scheme 16: RRM approach to spirocycles.
Scheme 17: RRM approach to bicyclic dihydropyrans.
Scheme 18: RCM–ROM–RCM cascade using non strained alkenyl heterocycles.
Scheme 19: First ROM–RCM–ROM–RCM cascade for the synthesis of trisaccharide 97.
Scheme 20: RRM of cyclohexene system.
Scheme 21: RRM approach to tricyclic spirosystem.
Scheme 22: RRM approach to bicyclic building block 108a.
Scheme 23: ROM–RCM protocol for the synthesis of the bicyclo[3.3.0]octene system.
Scheme 24: RRM protocol to bicyclic enone.
Scheme 25: RRM protocol toward the synthesis of the tricyclic system 118.
Scheme 26: RRM approach toward the synthesis of the tricyclic enones 122a and 122b.
Scheme 27: Synthesis of tricyclic and tetracyclic systems via RRM protocol.
Scheme 28: RRM protocol towards the synthesis of tetracyclic systems.
Scheme 29: RRM of the propargylamino[2.2.1] system.
Scheme 30: RRM of highly decorated bicyclo[2.2.1] systems.
Scheme 31: RRM protocol towards fused tricyclic compounds.
Scheme 32: RRM protocol to functionalized tricyclic systems.
Scheme 33: RRM approach to functionalized polycyclic systems.
Scheme 34: Sequential RRM approach to functionalized tricyclic ring system 166.
Scheme 35: RRM protocol to functionalized CDE tricyclic ring system of schintrilactones A and B.
Scheme 36: Sequential RRM approach to 7/5 fused bicyclic systems.
Scheme 37: Sequential ROM-RCM protocol for the synthesis of bicyclic sugar derivatives.
Scheme 38: ROM–RCM sequence of the norbornene derivatives 186 and 187.
Scheme 39: RRM approach toward highly functionalized bridge tricyclic system.
Scheme 40: RRM approach toward highly functionalized tricyclic systems.
Scheme 41: Synthesis of hexacyclic compound 203 by RRM approach.
Scheme 42: RRM approach toward C3-symmetric chiral trimethylsumanene 209.
Scheme 43: Triquinane synthesis via IMDA reaction and RRM protocol.
Scheme 44: RRM approach to polycyclic compounds.
Scheme 45: RRM strategy toward cis-fused bicyclo[3.3.0]carbocycles.
Scheme 46: RRM protocol towards the synthesis of bicyclic lactone 230.
Scheme 47: RRM approach to spiro heterocyclic compounds.
Scheme 48: RRM approach to spiro heterocyclic compounds.
Scheme 49: RRM approach to regioselective pyrrolizidine system 240.
Scheme 50: RRM approach to functionalized bicyclic derivatives.
Scheme 51: RRM approach to tricyclic derivatives 249 and 250.
Scheme 52: RRM approach to perhydroindoline derivative and spiro system.
Scheme 53: RRM approach to bicyclic pyran derivatives.
Scheme 54: RRM of various functionalized oxanorbornene systems.
Scheme 55: RRM to assemble the spiro fused-furanone core unit. (i) 129, benzene, 55 °C, 3 days; (ii) Ph3P=CH2B...
Scheme 56: RRM protocol to norbornenyl sultam systems.
Scheme 57: Ugi-RRM protocol for the synthesis of 2-aza-7-oxabicyclo system.
Scheme 58: Synthesis of spiroketal systems via RRM protocol.
Scheme 59: RRM approach to cis-fused heterotricyclic system.
Scheme 60: RRM protocol to functionalized bicyclic systems.
Scheme 61: ROM/RCM/CM cascade to generate bicyclic scaffolds.
Scheme 62: RCM of ROM/CM product.
Scheme 63: RRM protocol to bicyclic isoxazolidine ring system.
Scheme 64: RRM approach toward the total synthesis of (±)-8-epihalosaline (300).
Scheme 65: Sequential RRM approach to decalin 304 and 7/6 fused 305 systems.
Scheme 66: RRM protocol to various fused carbocyclic derivatives.
Scheme 67: RRM to cis-hydrindenol derivatives.
Scheme 68: RRM protocol towards the cis-hydrindenol derivatives.
Scheme 69: RRM approach toward the synthesis of diversed polycyclic lactams.
Scheme 70: RRM approach towards synthesis of hexacyclic compound 324.
Scheme 71: RRM protocol to generate luciduline precursor 327 with catalyst 2.
Scheme 72: RRM protocol to key building block 330.
Scheme 73: RRM approach towards the synthesis of key intermediate 335.
Scheme 74: RRM protocol to highly functionalized spiro-pyran system 339.
Scheme 75: RRM to various bicyclic polyether derivatives.
Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis
- David W. Manley and
- John C. Walton
Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173
- probably involved the coupling of the initial aminium radical cation with the radical anion formed by SET to the furanone substrate [46]. An interesting further convolution was observed in the TiO2 and ZnS promoted SCPC reactions of N,N-dimethylaniline (10) with furanone 6. A tandem radical addition
Graphical Abstract
Figure 1: Production and utilization of h+ and e– by photoactivation of a semiconductor.
Figure 2: Photoredox activity of TiO2 with moist air.
Scheme 1: TiO2 promoted oxidation of phenanthrene [29].
Scheme 2: SCPC assisted additions of allylic compounds to diazines and imines [40-42].
Scheme 3: TiO2 promoted addition and addition–cyclization reactions of tert-amines with electron-deficient al...
Scheme 4: Reactions of amines promoted by Pt-TiO2 [48,49].
Scheme 5: P25 Promoted alkylations of N-phenylmaleimide with diverse carboxylic acids [53,54]. aAccompanied by R–R d...
Scheme 6: SCPC cyclizations of aryloxyacetic acids with suitably sited alkene acceptors [54]. aYields in brackets...
Scheme 7: TiO2 promoted reactions of aryloxyacetic acids with maleic anhydride and maleimides [53,54].
Scheme 8: Photoredox addition–cyclization reactions of aryloxyacetic and related acids promoted by maleimide [63]....
Scheme 9: SCPC promoted homo-couplings and macrocyclizations with carboxylic acids [64].
Scheme 10: TiO2 promoted alkylations of alkenes with silanes [66] and thiols [67].
Scheme 11: TiO2 reduction of a nitrochromenone derivative [70].
Scheme 12: TiO2 mediated hydrodehalogenations and cyclizations of organic iodides [71].
Scheme 13: TiO2 promoted hydrogenations of maleimides, maleic anhydride and aromatic aldehydes [79].
Scheme 14: Mechanistic sketch of SCPC hydrogenation of aryl aldehydes.
Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules
- Thilo Focken and
- Stephen Hanessian
Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195
- through a conjugate addition sequence employing phosphonamide 28c, thereby setting two of the three stereocenters of the five-membered ring in a single step. Thus, deprotonation of chiral phosphonamide 28c and addition of the anion to 2(5H)-furanone (176) at −100 ºC, followed by trapping with excess
Graphical Abstract
Figure 1: Examples of phosphonamide reagents used in stereoselective synthesis.
Figure 2: Natural products and bioactive molecules synthesized using phosphonamide-based chemistry (atoms, bo...
Scheme 1: Olefination with cyclic phosphonamide anions, mechanistic rationale, and selected examples 27a–d [18].
Scheme 2: Asymmetric olefination with chiral phosphonamide anions and selected examples 31a–d [1,22].
Scheme 3: Synthesis of α-substituted phosphonic acids 33a–e by asymmetric alkylation of chiral phosphonamide ...
Scheme 4: Asymmetric conjugate additions of C2-symmetric chiral phosphonamide anions to cyclic enones, lacton...
Scheme 5: Asymmetric conjugate additions of P-chiral phosphonamide anions generated from 40a and 44a to cycli...
Scheme 6: Asymmetric cyclopropanation with chiral chloroallyl phosphonamide 47, mechanistic rationale, and se...
Scheme 7: Asymmetric cyclopropanation with chiral chloromethyl phosphonamide 28d [59].
Scheme 8: Stereoselective synthesis of cis-aziridines 57 from chiral chloroallyl phosphonamide 47a [62].
Scheme 9: Synthesis of phosphonamides by (A) Arbuzov reaction, (B) condensation of diamines with phosphonic a...
Figure 3: Original and revised structure of polyoxin A (69) [24-26].
Scheme 10: Synthesis of (E)-polyoximic acid (9) [24-26].
Figure 4: Key assembly strategy of acetoxycrenulide (10) [41,42].
Scheme 11: Total synthesis of (+)-acetoxycrenulide (10) [41,42].
Scheme 12: Synthesis squalene synthase inhibitor 19 by asymmetric sulfuration (A) and asymmetric alkylation (B...
Figure 5: Key assembly strategy of fumonisin B2 (20) and its tricarballylic acid fragment 105 [45,46].
Scheme 13: Final steps of the total synthesis of fumonisin B2 (20) [45,46].
Figure 6: Selected examples of two subclasses of β-lactam antibiotics – carbapenems (111 and 112) and trinems...
Scheme 14: Synthesis of tricyclic β-lactam antibiotic 123 [97].
Scheme 15: Total synthesis of (−)-anthoplalone (8) [56].
Figure 7: Protein tyrosine phosphatase (PTP) inhibitors 130, 131 and model compounds 16, 132 and 133 [68].
Scheme 16: Synthesis of model PTP inhibitors 16a,b [68].
Scheme 17: Synthesis of aziridine hydroxamic acid 17 as MMP inhibitor [63].
Scheme 18: Synthesis of methyl jasmonate (11) [48].
Figure 8: Structures of nudiflosides A (137) and D (13) [49].
Scheme 19: Total synthesis of the pentasubstituted cyclopentane core 159 of nudiflosides A (151) and D (13) an...
Figure 9: L-glutamic acid (161) and constrained analogues [57,124].
Scheme 20: Stereoselective synthesis of DCG-IV (162) [57].
Scheme 21: Stereoselective synthesis of mGluR agonist 21 [124].
Figure 10: Key assembly strategy of berkelic acid (15) [43].
Scheme 22: Total synthesis of berkelic acid (15) [43].
Figure 11: Key assembly strategy of jerangolid A (22) and ambruticin S (14) [27,28].
Scheme 23: Final assembly steps in the total synthesis of jerangolid A [27].
Scheme 24: Key assembly steps in the total synthesis of ambruticin S (14) [28].
Figure 12: General steroid construction strategy based on conjugate addition of 212 to cyclopentenone 48, exem...
Scheme 25: Total synthesis of estrone (12) [44].
A tandem Mannich addition–palladium catalyzed ring-closing route toward 4-substituted-3(2H)-furanones
- Jubi John,
- Eliza Târcoveanu,
- Peter G. Jones and
- Henning Hopf
Beilstein J. Org. Chem. 2014, 10, 1462–1470, doi:10.3762/bjoc.10.150
- . Keywords: aza-prostaglandin analogue; 3(2H)-furanone; Mannich addition; palladium catalysis; tandem reaction; Introduction Organic chemists welcome the introduction of facile tandem protocols because of the advantages of multiple bond formation in one-pot processes, which in turn makes the process
- closure of the primary adduct to form the furanone. In this paper, we report our investigations that extend the reaction to heteroatom-containing electrophiles such as imines and diazo esters. Results and Discussion Following the work on nitrostyrenes, Yan et al. also reported a two-step asymmetric route
- commenced our investigations with the reaction of tosylimine 1a and ethyl 4-chloroacetoacetate (2a) in the presence of 5 mol % of Pd(PPh3)4 and 2.0 equivalents of Na2CO3, in dioxane at 50 °C for 10 hours. The reaction afforded 4-substituted-3(2H)-furanone 3 in 57% yield (Scheme 2). Interestingly, we could
Graphical Abstract
Figure 1: Bioactive molecules I [19], II [26], III & IV [21,22] with 3(2H)-furanone moiety.
Scheme 1: Pd-catalyzed synthesis of 3(2H)-furanones from activated alkenes [40].
Scheme 2: Pd-catalyzed synthesis of 3(2H)-furanone from tosylimine 1a.
Figure 2: Generalisation with aromatic and aliphatic imines (reaction conditions: 1 (1.0 equiv), 2 (1.1 equiv...
Figure 3: Thermal ellipsoid diagrams (50% probability levels) of 4-substituted-3(2H)-furanones 7 (above) and ...
Scheme 3: Mechanism of formation of the 3(2H)-furanone derivative from an imine.
Scheme 4: Pd-catalyzed synthesis of 3(2H)-furanone from diazoester 19a.
Figure 4: Generalisation with diazo esters (reaction conditions: 19 (1.0 equiv), 2 (1.1 equiv), Pd(PPh3)4 (5 ...
Scheme 5: Synthesis of aza-prostaglandin analogue.
Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis
- Sebastian Krüger and
- Tanja Gaich
Beilstein J. Org. Chem. 2014, 10, 163–193, doi:10.3762/bjoc.10.14
- acid was converted to the corresponding anhydride, which could be reduced to the alcohol using NaBH4, followed by reoxidation with DMP to yield aldehyde 154. Attachment of furanone enolate 155 [134][135], followed by reoxidation yielded tricycle 156. Deprotection of the amine and the MOM-protected
Graphical Abstract
Scheme 1: Vogel’s first approach towards the divinylcyclopropane rearrangement [4] and characterization of cis-d...
Scheme 2: Transition states for the Cope rearrangement and the related DVCPR. Ts = transition state.
Scheme 3: Two possible mechanisms of trans-cis isomerizations of divinylcyclopropanes.
Scheme 4: Proposed biosynthesic pathway to ectocarpene (21), an inactive degradation product of a sexual pher...
Scheme 5: Proposed biosynthesis of occidenol (25) and related natural compounds.
Scheme 6: Gaich’s bioinspired system using the DVCPR to mimick the dimethylallyltryptophan synthase. DMAPP = ...
Scheme 7: Iguchi’s total synthesis of clavubicyclone, part 1.
Scheme 8: Iguchi’s total synthesis of clavubicyclone, part 2.
Scheme 9: Wender’s syntheses of the two pseudoguainanes confertin (50) and damsinic acid (51) and Pier’s appr...
Scheme 10: Overman’s total synthesis of scopadulcic acid B.
Scheme 11: Davies’ total syntheses of tremulenolide A and tremulenediol A.
Scheme 12: Davies formal [4 + 3] cycloaddition approach towards the formal synthesis of frondosin B.
Scheme 13: Davies and Sarpongs formal [4 + 3]-cycloaddition approach towards barekoxide (106) and barekol (107...
Scheme 14: Davies formal [4 + 3]-cycloaddition approach to 5-epi-vibsanin E (115) containing an intermediate c...
Scheme 15: Echavarren’s total synthesis of schisanwilsonene A (126) featuring an impressive gold-catalzed casc...
Scheme 16: Davies early example of a formal [4 + 3]-cycloaddition in alkaloids synthesis.
Scheme 17: Fukuyama’s total synthesis of gelsemine, part 1.
Scheme 18: Fukuyama’s total synthesis of gelsemine, featuring a divinylcyclopropane rearrangement, part 2.
Scheme 19: Kende’s total synthesis of isostemofoline, using a formal [4 + 3]-cycloaddition, including an inter...
Scheme 20: Danishefsky’s total synthesis of gelsemine, part 1.
Scheme 21: Danishefsky’s total synthesis of gelsemine, part 2.
Scheme 22: Fukuyama’s total synthesis of gelsemoxonine.
Scheme 23: Wender’s synthetic access to the core skeleton of tiglianes, daphnanes and ingenanes.
Scheme 24: Davies’ approach towards the core skeleton of CP-263,114 (212).
Scheme 25: Wood’s approach towards actinophyllic acid.
Scheme 26: Takeda’s approach towards the skeleton of the cyanthins, utilitizing the divinylcyclopropane rearra...
Scheme 27: Donaldson’s organoiron route towards the guianolide skeleton.
Scheme 28: Stoltz’s tandem Wolff/DVCPR rearrangement.
Scheme 29: Stephenson’s tandem photocatalysis/arylvinylcyclopropane rearrangement.
Scheme 30: Padwa’s rhodium cascade involving a DVCPR.
Scheme 31: Matsubara’s version of a DVCPR.
Scheme 32: Toste’s tandem gold-catalyzed Claisen-rearrangement/DVCPR.
Scheme 33: Ruthenium- and gold-catalyzed versions of tandem reactions involving a DVCPR.
Scheme 34: Tungsten, platinum and gold catalysed cycloisomerizations leading to a DVCPR.
Scheme 35: Reisman’s total synthesis of salvileucalin B, featuring an (undesired) vinylcyclopropyl carbaldehyd...
Scheme 36: Studies on the divinylepoxide rearrangement.
Scheme 37: Studies on the vinylcyclopropanecarbonyl rearrangement.
Scheme 38: Nitrogen-substituted variants of the divinylcyclopropane rearrangement.
Stereodivergent synthesis of jaspine B and its isomers using a carbohydrate-derived alkoxyallene as C3-building block
- Volker M. Schmiedel,
- Stefano Stefani and
- Hans-Ulrich Reissig
Beilstein J. Org. Chem. 2013, 9, 2564–2569, doi:10.3762/bjoc.9.291
- -azido group overcoming the steric hindrance of the slim alkyl chain. We assume that in both diastereomers the azido group occupies a pseudoaxial position shielding this face of the furanone ring and therefore steers the hydride attack to the other side. Similar observations have been reported for the
Graphical Abstract
Scheme 1: Structure of jaspine B 1 and its stereoisomers 2–4.
Scheme 2: Retrosynthetic analysis of jaspine B leading to pentadecanal and an alkoxyallene.
Scheme 3: Synthesis of racemic dihydrofuran 8.
Scheme 4: Synthesis of racemic jaspine B rac-1 and its diastereomer rac-2.
Scheme 5: Synthesis of dihydrofurans 14 and 15.
Scheme 6: Synthesis of jaspine B (1) and its (2S,3R,4R)-diastereomer 2.
Scheme 7: Protection and separation of the diastereomers.
Scheme 8: Reduction of the separated diastereomers leading to jaspine B (1) and its diastereomer 2.
Scheme 9: Route to ent-jaspine B (3) and the (2R,3S,4S)-diastereomer 4.
Microflow photochemistry: UVC-induced [2 + 2]-photoadditions to furanone in a microcapillary reactor
- Sylvestre Bachollet,
- Kimitada Terao,
- Shin Aida,
- Yasuhiro Nishiyama,
- Kiyomi Kakiuchi and
- Michael Oelgemöller
Beilstein J. Org. Chem. 2013, 9, 2015–2021, doi:10.3762/bjoc.9.237
- , Takayama-cho, Ikoma, Nara 630-0101, Japan 10.3762/bjoc.9.237 Abstract [2 + 2]-Cycloadditions of cyclopentene and 2,3-dimethylbut-2-ene to furanone were investigated under continuous-flow conditions. Irradiations were conducted in a FEP-microcapillary module which was placed in a Rayonet chamber
- chemistry; furanone; microflow chemistry; photochemistry; Introduction Continuous-flow chemistry has recently emerged as a new methodology in organic chemistry [1][2][3][4]. The combination of microstructured dimensions and flow operations has also proven advantageous for photochemical applications [5][6
- concentrated to dryness and the crude product was analyzed by 1H NMR spectroscopy. Conversions were determined by comparing the integration areas of selected signals from the starting furanone and the cycloaddition product. In selected cases, the pure products were isolated by column chromatography for
Graphical Abstract
Scheme 1: General [2 + 2]-cycloaddition of furanones with alkenes.
Figure 1: Rayonet chamber reactor (RMR-600; Southern New England) with quartz test tubes. A 10 AU-cent coin i...
Figure 2: Microcapillary reactor. (a) Setup with inserted μ-capillary unit. A 10 AU-cent coin is shown for co...
Figure 3: (a) UV-spectrum of 1 (in MeCN) vs emission spectrum of the UVC lamp. (b) Light-penetration profile ...
Scheme 2: [2 + 2]-Cycloadditions of furanone 1 with cyclopentene (2).
Scheme 3: [2 + 2]-Cycloadditions of furanone 1 with 2,3-dimethylbut-2-ene (4).
Flow photochemistry: Old light through new windows
- Jonathan P. Knowles,
- Luke D. Elliott and
- Kevin I. Booker-Milburn
Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229
Graphical Abstract
Figure 1: An immersion-well batch reactor with 125 W medium pressure Hg lamp.
Figure 2: Transmission profile of a 0.05 M solution, ε = 200 M−1 cm−1.
Figure 3: Schematic of a typical microflow photochemical reactor (above) and detail of a triple-channel micro...
Figure 4: Schematic of a typical macroflow photochemical reactor (above) and images of the FEP photochemical ...
Scheme 1: [2 + 2] photocycloadditions of enones with enol derivatives.
Scheme 2: Competing reactions in an intramolecular [2 + 2] photocycloaddition.
Scheme 3: Diastereocontrolled cycloaddition of a cyclic enone with cyclopentene.
Scheme 4: Comparison of yields and reaction times for a batch reactor with a microflow system.
Scheme 5: Intramolecular [2 + 2] photocycloaddition.
Scheme 6: Paterno–Büchi reaction of benzophenone with an allylic alcohol.
Scheme 7: Photooxygenation of cyclopentadiene.
Scheme 8: Preparation of the anthelmintic ascaridole 23.
Scheme 9: Production of rose oxide 27 from (−)-β-citronellol (24).
Scheme 10: Photocatalytic alkylation of benzylamine.
Scheme 11: Photocatalytic reduction of 4-nitroacetophenone.
Scheme 12: Conversion of L-lysine to L-pipecolinic acid.
Scheme 13: Photocatalytic hydrodehalogenation.
Scheme 14: Photocatalytic aza-Henry reactions.
Scheme 15: Photocatalytic α-alkylation of aliphatic ketones.
Scheme 16: Decarboxylative photochemical additions.
Scheme 17: Photochemical addition of isopropanol to furanones.
Scheme 18: Photochemical addition of methanol to limonene.
Scheme 19: Light-promoted reduction of flavone.
Scheme 20: Photoreduction of benzophenone with benzhydrol.
Scheme 21: Barton reaction in a microflow system.
Scheme 22: Microflow synthesis of vitamin D3.
Scheme 23: photochemical chlorination of cyclohexane.
Scheme 24: photochemical cyanation of pyrene.
Scheme 25: Intermolecular [2 + 2] cycloaddition of maleimide (76) and intramolecular [2 + 2] cycloaddition of ...
Scheme 26: Intramolecular [5 + 2] cycloaddition of maleimide under flow conditions.
Scheme 27: Intramolecular [5 + 2] cycloaddition as a key step in the synthesis of (±)-neostenine.
Scheme 28: In situ generation of a thioaldehyde by photolysis of a phenacyl sulfide.
Scheme 29: Photodimerisation of maleic anhydride.
Scheme 30: [2 + 2] cycloaddition of a chiral enone with ethylene.
Scheme 31: Intramolecular [2 + 2] cycloaddition of a cyclopentenone.
Scheme 32: Photochemical Wolff rearrangement and cyclisation to β-lactams.
Scheme 33: Photochemical rearrangement of aryl azides.
Scheme 34: Rearrangement of quinoline N-oxides to quinolones.
Scheme 35: Photochemical rearrangement of cyclobutenones.
Scheme 36: Photoisomerisation en route to a vitamin-D derivative.
Scheme 37: Schematic of the Seeberger photooxygenation apparatus and sensitised photooxygenation of citronello...
Scheme 38: Sensitised photooxygenation of dihydroartemisinic acid.
Scheme 39: Photochemical preparation of CpRu(MeCN)3PF6.
Scheme 40: In situ photochemical generation and reaction of a [CpRu]+ catalyst.
Scheme 41: Intermolecular alkene–alkyne coupling with photogenerated catalyst.
Scheme 42: PET deoxygenation of nucleosides.
Scheme 43: Photochemical defluorination of DABFT.
Scheme 44: Aromatic azide reduction by visible-light-mediated photocatalysis.
Scheme 45: Examples of visible-light-mediated reactions.
Scheme 46: Visible-light-mediated formation of iminium ions.
Scheme 47: Examples of visible-light-mediated photocatalytic reactions.
Scheme 48: Anhydride formation from a visible-light-mediated process.
Scheme 49: Light-mediated conjugate addition of glycosyl bromide 141 to acrolein.
Scheme 50: Visible-light-mediated photocyclisation to [5]helicene.
When cyclopropenes meet gold catalysts
- Frédéric Miege,
- Christophe Meyer and
- Janine Cossy
Beilstein J. Org. Chem. 2011, 7, 717–734, doi:10.3762/bjoc.7.82
- products: Furanone 35a (52%) and indene 36a (20%). The former compound arose from intramolecular trapping of the intermediate organogold species 37a by the carbonyl group of the ester at C3, followed by hydrolysis of the resulting α-methoxyfuran 38a. A similar result was reported by Wang et al. [21
- two compounds: Furanone 35a (40%) and indene 36a (39%) both devoid of a trimethylsilyl group. Since protodesilylation took place readily, it is likely that the allylic silanes 35’e and 36’e were the initially generated products. Their formation could be explained by regioselective electrophilic
Graphical Abstract
Scheme 1: General reactivity of cyclopropenes in the presence of gold catalysts.
Scheme 2: Cationic organogold species generated from cyclopropenone acetals.
Scheme 3: Rotation barriers around the C2–C3 bond (M06 DFT calculations).
Scheme 4: Au–C1 bond length in organogold species of type D.
Scheme 5: Gold-catalyzed addition of alcohols or water to cyclopropene 8.
Scheme 6: Gold-catalyzed addition of alcohols to cyclopropene 10.
Scheme 7: Mechanism of the gold-catalyzed addition of alcohols to cyclopropenes.
Scheme 8: Synthesis of tert-allylic ethers from cyclopropenes and allenes.
Scheme 9: Oxidation of the intermediate gold–carbene with diphenylsulfoxide.
Scheme 10: Gold, copper and Lewis acid-catalyzed reactions of cyclopropene 18.
Scheme 11: Mechanism of the Lewis acid-catalyzed reactions of cyclopropene 18.
Scheme 12: Gold-catalyzed rearrangement of vinylcyclopropenes 25.
Scheme 13: Gold-catalyzed rearrangement of cyclopropenes 27 to indenes 28.
Scheme 14: Gold-catalyzed rearrangement of cyclopropenes 29 to indenes 30.
Scheme 15: Gold-catalyzed rearrangement of cyclopropenyl ester 34a.
Scheme 16: Gold-catalyzed reactions of cyclopropenyl esters 34b–34d.
Scheme 17: Gold-catalyzed reactions of cyclopropenylsilane 34e.
Scheme 18: Gold-catalyzed rearrangement of cyclopropenylmethyl acetates.
Scheme 19: Mechanism of the gold-catalyzed rearrangement of cyclopropenes 39.
Scheme 20: Gold-catalyzed cyclopropanation of styrene with cyclopropene 8.
Scheme 21: Representative reactions of carbene precursors on gold metal.
Scheme 22: Intermolecular olefin cyclopropanation with gold carbenes generated from cyclopropenes.
Scheme 23: Gold-catalyzed formation of trienes from cyclopropenes and furans.
Scheme 24: Gold-catalyzed formation of trienes from cyclopropenes and furans.
Scheme 25: Gold-catalyzed formation of trienes from cyclopropenes and furans.
Scheme 26: Gold-catalyzed cycloisomerization of cyclopropene-ene 59.
Scheme 27: Gold-catalyzed cycloisomerization of substituted allyl cyclopropenyl carbinyl ethers 62a–62f.
Scheme 28: Gold-catalyzed cycloisomerization of cyclopropene-enes.
Scheme 29: Gold-catalyzed cycloisomerization of cyclopropene-ynes.
Scheme 30: Formation of products arising from a double cleavage process in the gold-catalyzed cycloisomerizati...
Scheme 31: Gold-catalyzed cycloisomerization of cyclopropene-ynes involving a double cleavage process.
Scheme 32: Gold-catalyzed reaction of cyclopropene-ynes, cyclopropene-enes and cyclopropene-allenes.
