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Search for "substrate selectivity" in Full Text gives 15 result(s) in Beilstein Journal of Organic Chemistry.
Enhancing structural diversity of terpenoids by multisubstrate terpene synthases
- Min Li and
- Hui Tao
Beilstein J. Org. Chem. 2024, 20, 959–972, doi:10.3762/bjoc.20.86
- products, 3-ethyl-3-buten-1-ol (139) and 3-propyl-3-buten-1-ol (140), have potent fuel properties, highlighting the potential of this strategy for producing isoprenol analogs as next-generation biofuels (Figure 10b) [62]. Conclusion During terpenoid biosynthesis, most TSs have strict substrate selectivity
Graphical Abstract
Figure 1: Biosynthetic pathway of terpenoids. Valuable terpenoids, noncanonical C11 and C16 terpenes are show...
Figure 2: Representative terpenoids produced by plant MSTSs. a) 6 and 7 are products of PamTps1 from Plectran...
Figure 3: The structure of representative terpene products of MSTSs. a) From fungi: compounds 30–33 are produ...
Figure 4: Terpenoid products of TSs using chemically synthesized noncanonical prenyl substrates. a) Products ...
Figure 5: Biotransformation of noncanonical prenyl analogs 60–65 using two terpene synthases, limonene syntha...
Figure 6: Noncanonical substrates for mechanism studies and their conversion to new terpenoids. a) New terpen...
Figure 7: A series of prenyl diphosphate building blocks produced by different IPP methyltransferases. humMT ...
Figure 8: The structure of noncanonical prenyl substrates generated by C-methyltransferases and variants. a) ...
Figure 9: Structures of C16 terpenes identified via genome mining of C16 biosynthetic gene clusters from bact...
Figure 10: a) Precursors and final products of the MVA pathway and LMVA pathway. b) The structure of C6- and C7...
Supramolecular approaches to mediate chemical reactivity
- Pablo Ballester,
- Qi-Qiang Wang and
- Carmine Gaeta
Beilstein J. Org. Chem. 2022, 18, 1463–1465, doi:10.3762/bjoc.18.152
- catalysts were designed that showed substrate selectivity, turnover, regioselectivity, and stereoselectivity [5][6][7][8][9][10][11][12][13][14]. Supramolecular architectures with an internal cavity are potential candidates to work as supramolecular catalysts [5][6][7][8][9][10][11][12][13][14]. The first
Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis
- Prodip Howlader and
- Michael Schmittel
Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62
- distance, now though for proximity catalysis using acyl transfer. The utility of this approach was demonstrated when a duo of catalysts was used for achieving substrate selectivity [133]. In detail, nanoswitch [Cu(130)]+ was transformed into the slow rotor [Cu2(130)]2+ (k298 = 1.34 s−1) upon the addition
Graphical Abstract
Figure 1: Butterfly 1 (Figure was reprinted with permission from [45]. Copyright 2012 American Chemical Society. ...
Figure 2: Synthesis of the three-component heteroleptic molecular boat 8 and its use as a catalyst for the Kn...
Figure 3: Synthesis of the two-component triangle 14 and three-component heteroleptic prism 15 [59]. Figure was a...
Figure 4: Catalytic Michael addition reaction using the urea-decorated molecular prism 15 [59].
Figure 5: Self-assembly of two-component tetragonal prismatic architectures with different cavity size. Figur...
Figure 6: Construction of artificial LHS using rhodamine B as an acceptor and 24b as donor generating a photo...
Figure 7: Synthesis of supramolecular spheres with varying [AuCl] concentration inside the cavity. Figure was...
Figure 8: Hydroalkoxylation reaction of γ-allenol 34 in the presence of [AuCl]-encapsulated molecular spheres ...
Figure 9: Two-component heteroleptic triangles of different size containing a BINOL functionality. Figure was...
Figure 10: Asymmetric conjugate addition of chalcone 42 with trans-styrylboronic acid (43) catalyzed by BINOL-...
Figure 11: Encapsulation of monophosphoramidite-Rh(I) catalyst into a heteroleptic tetragonal prismatic cage 47...
Figure 12: (a) Representations of the basic HETPYP, HETPHEN, and HETTAP complex motifs. (b) The three-componen...
Figure 13: Two representative four-component rotors, with a (top) two-arm stator and (bottom) a four-arm stato...
Figure 14: Four-component rotors with a monohead rotator. Figure was adapted with permission from [94]. Copyright ...
Figure 15: (left) Click reaction catalyzed by rotors [Cu2(55)(60)(X)]2+. (right) Yield as a function of the ro...
Figure 16: A supramolecular AND gate. a) In truth table state (0,0) two nanoswitches serve as the receptor ens...
Figure 17: Two supramolecular double rotors (each has two rotational axes) and reference complex [Cu(78)]+ for...
Figure 18: The slider-on-deck system (82•X) (X = 83, 84, or 85). Figure is from [98] and was reprinted from the jo...
Figure 19: Catalysis of a conjugated addition reaction in the presence of the slider-on-deck system (82•X) (X ...
Figure 20: A rotating catalyst builds a catalytic machinery. For catalysis of the catalytic machinery, see Figure 21. F...
Figure 21: Catalytic machinery. Figure was adapted from [100] (“Evolution of catalytic machinery: three-component n...
Figure 22: An information system based on (re)shuffling components between supramolecular structures [99]. Figure ...
Figure 23: Switching between dimeric heteroleptic and homoleptic complex for OFF/ON catalytic formation of rot...
Figure 24: A chemically fueled catalytic system [112]. Figure was adapted from [112]. Copyright 2021 American Chemical S...
Figure 25: (Top) Operation of a fuel acid. (Bottom) Knoevenagel addition [112].
Figure 26: Development of the yield of Knoevenagel product 118 in a fueled system [112]. Figure was reprinted with ...
Figure 27: Weak-link strategy to increased catalytic activity in epoxide opening [119]. Figure was adapted from [24]. C...
Figure 28: A ON/OFF polymerization switch based on the weak-link approach [118]. Figure was reprinted with permissi...
Figure 29: A weak-link switch turning ON/OFF a Diels–Alder reaction [132]. Figure was reprinted with permission fro...
Figure 30: A catalyst duo allowing selective activation of one of two catalytic acylation reactions [133] upon subs...
Figure 31: A four-state switchable nanoswitch (redrawn from [134]).
Figure 32: Sequential catalysis as regulated by nanoswitch 138 and catalyst 139 in the presence of metal ions ...
Figure 33: Remote control of ON/OFF catalysis administrated by two nanoswitches through ion signaling (redrawn...
Insight into functionalized-macrocycles-guided supramolecular photocatalysis
- Minzan Zuo,
- Krishnasamy Velmurugan,
- Kaiya Wang,
- Xueqi Tian and
- Xiao-Yu Hu
Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15
- advantages of the macrocycles in photocatalysis including: i) substrate selectivity, ii) controllability of the rate of photochemical reactions, iii) the close proximity to substrates in a confined space, iv) the generation of a stabilized high-energy transition state, and v) macrocyclic-cavity-size
Graphical Abstract
Figure 1: Chemical structures of representative macrocycles.
Figure 2: Ba2+-induced intermolecular [2 + 2]-photocycloaddition of crown ether-functionalized substrates 1 a...
Figure 3: Energy transfer system constructed of a BODIPY–zinc porphyrin–crown ether triad assembly bound to a...
Figure 4: The sensitizer 5 was prepared by a flavin–zinc(II)–cyclen complex for the photooxidation of benzyl ...
Figure 5: Enantiodifferentiating Z–E photoisomerization of cyclooctene sensitized by a chiral sensitizer as t...
Figure 6: Structures of the modified CDs as chiral sensitizing hosts. Adapted with permission from [24], Copyrigh...
Figure 7: Supramolecular 1:1 and 2:2 complexations of AC with the cationic β-CD derivatives 16–21 and subsequ...
Figure 8: Construction of the TiO2–AuNCs@β-CD photocatalyst. Republished with permission of The Royal Society...
Figure 9: Visible-light-driven conversion of benzyl alcohol to H2 and a vicinal diol or to H2 and benzaldehyd...
Figure 10: (a) Structures of CDs, (b) CoPyS, and (c) EY. Republished with permission of The Royal Society of C...
Figure 11: Conversion of CO2 to CO by ReP/HO-TPA–TiO2. Republished with permission of The Royal Society of Che...
Figure 12: Thiacalix[4]arene-protected TiO2 clusters for H2 evolution. Reprinted with permission from [37], Copyri...
Figure 13: 4-Methoxycalix[7]arene film-based TiO2 photocatalytic system. Reprinted from [38], Materials Today Chem...
Figure 14: (a) Photodimerization of 6-methylcoumarin (22). (b) Catalytic cycle for the photodimerization of 22...
Figure 15: Formation of a supramolecular PDI–CB[7] complex and structures of monomers and the chain transfer a...
Figure 16: Ternary self-assembled system for photocatalytic H2 evolution (a) and structure of 27 (b). Figure 16 reprodu...
Figure 17: Structures of COP-1, CMP-1, and their substrate S-1 and S-2.
Figure 18: Supramolecular self-assembly of the light-harvesting system formed by WP5, β-CAR, and Chl-b. Reprod...
Figure 19: Photocyclodimerization of AC based on WP5 and WP6.
Fluorinated phenylalanines: synthesis and pharmaceutical applications
- Laila F. Awad and
- Mohammed Salah Ayoup
Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91
- stability and substrate selectivity. 5.1. Applications of FPhe derivatives in positron emission tomography (PET) The molecular imaging technique positron emission tomography (PET) provides information on tumor metabolism, which allows for a more accurate diagnostic and therapy response in neuro-oncology
Graphical Abstract
Figure 1: Categories I–V of fluorinated phenylalanines.
Scheme 1: Synthesis of fluorinated phenylalanines via Jackson’s method.
Scheme 2: Synthesis of all-cis-tetrafluorocyclohexylphenylalanines.
Scheme 3: Synthesis of ʟ-4-[sulfono(difluoromethyl)]phenylalanine (nPt: neopentyl, TCE: trichloroethyl).
Scheme 4: Synthesis of ʟ-4-[sulfono(difluoromethyl)]phenylalanine derivatives 17.
Scheme 5: Synthesis of fluorinated Phe analogues from Cbz-protected aminomalonates.
Scheme 6: Synthesis of tetrafluorophenylalanine analogues via the 3-methyl-4-imidazolidinone auxiliary 25.
Scheme 7: Synthesis of tetrafluoro-Phe derivatives via chiral auxiliary 31.
Scheme 8: Synthesis of 2,5-difluoro-Phe and 2,4,5-trifluoro-Phe via Schöllkopf reagent 34.
Scheme 9: Synthesis of 2-fluoro- and 2,6-difluoro Fmoc-Phe derivatives starting from chiral auxiliary 39.
Scheme 10: Synthesis of 2-[18F]FPhe via chiral auxiliary 43.
Scheme 11: Synthesis of FPhe 49a via photooxidative cyanation.
Scheme 12: Synthesis of FPhe derivatives via Erlenmeyer azalactone synthesis.
Scheme 13: Synthesis of (R)- and (S)-2,5-difluoro Phe via the azalactone method.
Scheme 14: Synthesis of 3-bromo-4-fluoro-(S)-Phe (65).
Scheme 15: Synthesis of [18F]FPhe via radiofluorination of phenylalanine with [18F]F2 or [18F]AcOF.
Scheme 16: Synthesis of 4-borono-2-[18F]FPhe.
Scheme 17: Synthesis of protected 4-[18F]FPhe via arylstannane derivatives.
Scheme 18: Synthesis of FPhe derivatives via intermediate imine formation.
Scheme 19: Synthesis of FPhe derivatives via Knoevenagel condensation.
Scheme 20: Synthesis of FPhe derivatives 88a,b from aspartic acid derivatives.
Scheme 21: Synthesis of 2-(2-fluoroethyl)phenylalanine derivatives 93 and 95.
Scheme 22: Synthesis of FPhe derivatives via Zn2+ complexes.
Scheme 23: Synthesis of FPhe derivatives via Ni2+ complexes.
Scheme 24: Synthesis of 3,4,5-trifluorophenylalanine hydrochloride (109).
Scheme 25: Synthesis of FPhe derivatives via phenylalanine aminomutase (PAM).
Scheme 26: Synthesis of (R)-2,5-difluorophenylalanine 115.
Scheme 27: Synthesis of β-fluorophenylalanine via 2-amino-1,3-diol derivatives.
Scheme 28: Synthesis of β-fluorophenylalanine derivatives via the oxazolidinone chiral auxiliary 122.
Scheme 29: Synthesis of β-fluorophenylalanine from pyruvate hemiketal 130.
Scheme 30: Synthesis of β-fluorophenylalanine (136) via fluorination of β-hydroxyphenylalanine (137).
Scheme 31: Synthesis of β-fluorophenylalanine from aziridine derivatives.
Scheme 32: Synthesis of β-fluorophenylalanine 136 via direct fluorination of pyruvate esters.
Scheme 33: Synthesis of β-fluorophenylalanine via fluorination of ethyl 3-phenylpyruvate enol using DAST.
Scheme 34: Synthesis of β-fluorophenylalanine derivatives using photosensitizer TCB.
Scheme 35: Synthesis of β-fluorophenylalanine derivatives using Selectflour and dibenzosuberenone.
Scheme 36: Synthesis of protected β-fluorophenylalanine via aziridinium intermediate 150.
Scheme 37: Synthesis of β-fluorophenylalanine derivatives via fluorination of α-hydroxy-β-aminophenylalanine d...
Scheme 38: Synthesis of β-fluorophenylalanine derivatives from α- or β-hydroxy esters 152a and 155.
Scheme 39: Synthesis of a series of β-fluoro-Phe derivatives via Pd-catalyzed direct fluorination of β-methyle...
Scheme 40: Synthesis of series of β-fluorinated Phe derivatives using quinoline-based ligand 162 in the Pd-cat...
Scheme 41: Synthesis of β,β-difluorophenylalanine derivatives from 2,2-difluoroacetaldehyde derivatives 164a,b....
Scheme 42: Synthesis of β,β-difluorophenylalanine derivatives via an imine chiral auxiliary.
Scheme 43: Synthesis of α-fluorophenylalanine derivatives via direct fluorination of protected Phe 174.
Figure 2: Structures of PET radiotracers of 18FPhe derivatives.
Figure 3: Structures of melfufen (179) and melphalan (180) anticancer drugs.
Figure 4: Structure of gastrazole (JB95008, 181), a CCK2 receptor antagonist.
Figure 5: Dual CCK1/CCK2 antagonist 182.
Figure 6: Structure of sitagliptin (183), an antidiabetic drug.
Figure 7: Structure of retaglpitin (184) and antidiabetic drug.
Figure 8: Structure of evogliptin (185), an antidiabetic drug.
Figure 9: Structure of LY2497282 (186) a DPP-4 inhibitor for the treatment of type II diabetes.
Figure 10: Structure of ulimorelin (187).
Figure 11: Structure of GLP1R (188).
Figure 12: Structures of Nav1.7 blockers 189 and 190.
A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions
- Munmun Ghosh,
- Valmik S. Shinde and
- Magnus Rueping
Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264
- to the corresponding amino acid via electrochemical reduction of FAD in AOx by electron mediator ADPy. It should be noted that the authors also reported the limitation of this electrochemical method in terms of substrate selectivity of the enzymes used [44]. Electrochemical asymmetric oxidation using
Graphical Abstract
Figure 1: General classification of asymmetric electroorganic reactions.
Scheme 1: Asymmetric reduction of 4-acetylpyridine using a modified graphite cathode.
Scheme 2: Asymmetric hydrogenation of ketones using Raney nickel powder electrodes modified with optically ac...
Scheme 3: Asymmetric reduction of prochiral activated olefins with a poly-ʟ-valine-coated graphite cathode.
Scheme 4: Asymmetric reduction of prochiral carbonyl compounds, oximes and gem-dibromides on a poly-ʟ-valine-...
Scheme 5: Asymmetric hydrogenation of prochiral ketones with poly[RuIII(L)2Cl2]+-modified carbon felt cathode...
Scheme 6: Asymmetric hydrogenation of α-keto esters using chiral polypyrrole film-coated cathode incorporated...
Scheme 7: Quinidine and cinchonidine alkaloid-induced asymmetric electroreduction of acetophenone.
Scheme 8: Asymmetric electroreduction of 4- and 2-acetylpyridines at a mercury cathode in the presence of a c...
Scheme 9: Enantioselective reduction of 4-methylcoumarin in the presence of catalytic yohimbine.
Scheme 10: Cinchonine-induced asymmetric electrocarboxylation of 4-methylpropiophenone.
Scheme 11: Enantioselective hydrogenation of methyl benzoylformate using an alkaloid entrapped silver cathode.
Scheme 12: Alkaloid-induced enantioselective hydrogenation using a Cu nanoparticle cathode.
Scheme 13: Alkaloid-induced enantioselective hydrogenation of aromatic ketones using a bimetallic Pt@Cu cathod...
Scheme 14: Enantioselective reduction of ketones at mercury cathode using N,N'-dimethylquininium tetrafluorobo...
Scheme 15: Asymmetric synthesis of an amino acid using an electrode modified with amino acid oxidase and elect...
Scheme 16: Asymmetric oxidation of p-tolyl methyl sulfide using chemically modified graphite anode.
Scheme 17: Asymmetric oxidation of unsymmetric sulfides using poly(amino acid)-coated electrodes.
Scheme 18: Enantioselective, electocatalytic oxidative coupling on TEMPO-modified graphite felt electrode in t...
Scheme 19: Asymmetric electrocatalytic oxidation of racemic alcohols on a TEMPO-modified graphite felt electro...
Scheme 20: Asymmetric electrocatalytic lactonization of diols on TEMPO-modified graphite felt electrodes.
Scheme 21: Asymmetric electrochemical pinacolization in a chiral solvent.
Scheme 22: Asymmetric electroreduction using a chiral supporting electrolyte.
Scheme 23: Asymmetric anodic oxidation of enol acetates using chiral supporting electrolytes.
Scheme 24: Kinetic resolution of primary amines using a chiral N-oxyl radical mediator.
Scheme 25: Chiral N-oxyl-radical-mediated kinetic resolution of secondary alcohols via electrochemical oxidati...
Scheme 26: Chiral iodoarene-mediated asymmetric electrochemical lactonization.
Scheme 27: Os-catalyzed electrochemical asymmetric dihydroxylation of olefins using the Sharpless ligand and i...
Scheme 28: Asymmetric electrochemical epoxidation of olefins catalyzed by a chiral Mn-salen complex.
Scheme 29: Asymmetric electrooxidation of 1,2-diols, and amino alcohols using a chiral copper catalyst.
Scheme 30: Mechanism of asymmetric electrooxidation of 1,2-diols, and amino alcohols using a chiral copper cat...
Scheme 31: Enantioselective electrocarboxylation catalyzed by an electrogenerated chiral [CoI(salen)]− complex....
Scheme 32: Asymmetric oxidative cross coupling of 2-acylimidazoles with silyl enol ethers.
Scheme 33: Ni-catalyzed asymmetric electroreductive cleavage of allylic β-keto ester 89.
Scheme 34: Asymmetric alkylation using a combination of electrosynthesis and a chiral Ni catalyst.
Scheme 35: Mechanism of asymmetric alkylation using a combination of electrosynthesis and a chiral Ni catalyst....
Scheme 36: Asymmetric epoxidation by electrogenerated percarbonate and persulfate ions in the presence of chir...
Scheme 37: α-Oxyamination of aldehydes via anodic oxidation catalyzed by chiral secondary amines.
Scheme 38: The α-alkylation of aldehydes via anodic oxidation catalyzed by chiral secondary amines.
Scheme 39: Mechanism of α-alkylation of aldehydes via anodic oxidation catalyzed by chiral secondary amines.
Scheme 40: Electrochemical chiral secondary amine-catalyzed intermolecular α-arylation of aldehydes.
Scheme 41: Mechanism of electrochemical chiral secondary amine-catalyzed intermolecular α-arylation of aldehyd...
Scheme 42: Asymmetric cross-dehydrogenative coupling of tertiary amines with simple ketones via an electrochem...
Scheme 43: Electroenzymatic asymmetric reduction using enoate reductase.
Scheme 44: Assymetric reduction using alcohol dehydrogenase as the electrocatalyst.
Scheme 45: Asymmetric electroreduction catalyzed by thermophilic NAD-dependent alcohol dehydrogenase.
Scheme 46: Asymmetric epoxidation of styrene by electrochemical regeneration of flavin-dependent monooxygenase....
Scheme 47: Asymmetric electroreduction using a chloroperoxidase catalyst.
Scheme 48: Asymmetric electrochemical transformation mediated by hydrophobic vitamin B12.
Scheme 49: Diastereoselective cathodic reduction of phenylglyoxalic acids substituted with amines as chiral au...
Scheme 50: Ni-catalyzed asymmetric electroreductive cross coupling of aryl halides with α-chloropropanoic acid...
Scheme 51: Electrochemical Mannich addition of silyloxyfuran to in situ-generated N-acyliminium ions.
Scheme 52: Stereoselective electroreductive homodimerization of cinnamates attached to a camphor-derived chira...
Scheme 53: Diastereoselective electrochemical carboxylation of chiral α-bromocarboxylic acid derivatives.
Scheme 54: Electrocatalytic stereoselective conjugate addition of chiral β-dicarbonyl compounds to methyl viny...
Scheme 55: Stereoselective electrochemical carboxylation of chiral cinnamic acid derivatives under a CO2 atmos...
Scheme 56: Electrochemical diastereoselective α-alkylation of pyrrolidines attached with phosphorus-derived ch...
Scheme 57: Electrogenerated cyanomethyl anion-induced synthesis of chiral cis-β-lactams from amides bearing ch...
Scheme 58: Diastereoselective anodic oxidation followed by intramolecular cyclization of ω-hydroxyl amides bea...
Scheme 59: Electrochemical deprotonation of Ni(II) glycinate containing (S)-BPB as a chiral auxiliary: diaster...
Scheme 60: Enantioselective electroreductive coupling of diaryl ketones with α,β-unsaturated carbonyl compound...
Scheme 61: Asymmetric total synthesis of ropivacaine and its analogues using a electroorganic reaction as a ke...
Scheme 62: Asymmetric total synthesis of (−)-crispine A and its natural enantiomer via anodic cyanation of tet...
Scheme 63: Asymmetric oxidative electrodimerization of cinnamic acid derivatives as key step for the synthesis...
Selectivity in multiple multicomponent reactions: types and synthetic applications
- Ouldouz Ghashghaei,
- Francesca Seghetti and
- Rodolfo Lavilla
Beilstein J. Org. Chem. 2019, 15, 521–534, doi:10.3762/bjoc.15.46
- helped to pave the way of combinatorial chemistry and its applications for the fast generation of pharmacological hits through library deconvolution. The reactivity of the system led to complex product mixtures, with no practical substrate selectivity. However, if in analogous experiments several
Graphical Abstract
Scheme 1: Selectivity levels found in multiple multicomponent reactions. I) Innate selectivity; II) sequentia...
Scheme 2: Indiscriminate double Ugi MCR upon pyridine-2,6-dicarboxylic acid.
Scheme 3: Representative examples of MCR-polymer synthesis. A) Biginelli HTS of polymers; B) Passerini;- C) U...
Scheme 4: Concept of multicomponent macrocyclization.
Scheme 5: Supramolecular structures out of MMCR macrocyclizations.
Scheme 6: Macrocyclization by MMCRs. A) Staudinger MCR; B) boronic-imine MCR.
Scheme 7: Selective Sequential MMCRs. A and B) MCRs involving terephthalaldehyde; C) Multiple GBB processes w...
Scheme 8: Biased substrates for selective MMCRs.
Scheme 9: The Union concept. A) Asinger–Ugi combination; B) Passerini–Ugi/azide from anthranilic acid; C) Pas...
Scheme 10: Relevant examples of consecutive MCRs exploiting the Union Concept. A) Petasis-Ugi combination; B) ...
Scheme 11: Selective MMCRs featuring FGs with distinct reactivity along the sequence. A) Synthesis of aminomet...
Scheme 12: High order MMCRs. A) Ugi/Ugi–Smiles 7C combination; B) imidazoline-N-cyanomethylamide-Ugi union lea...
Scheme 13: Consecutive Ugi 4CR-deprotection–Ugi 4CR strategy towards A) PNA oligomers and B) peptidic tetrazol...
Scheme 14: Sequential Ugi 4CR-deprotection access to cyclopeptoids.
Scheme 15: Stepwise access to 6-aminopenicillanic acid derivative through an Asinger, deprotection, Joullié ap...
Scheme 16: A triple MCR-deprotection approach affording anticancer peptidomimetics.
Nanoreactors for green catalysis
- M. Teresa De Martino,
- Loai K. E. A. Abdelmohsen,
- Floris P. J. T. Rutjes and
- Jan C. M. van Hest
Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61
- substrates were subsequently tested using 10 mol % of this catalyst in water at room temperature. The achievement of this study was not only on the stereoselectivity of the catalysts, but also on the substrate selectivity (Table 4): the preferred substrates are water-insoluble, suggesting that the reaction
- was carried out in organic solvent [80] (Figure 4). As depicted in Table 5, substrate selectivity was observed when catalytic polymersomes were used, reasonably ascribed to a concentration effect, with more hydrophobic substrates leading to an increased local concentration around the catalyst in the
Graphical Abstract
Figure 1: Assembly of catalyst-functionalized amphiphilic block copolymers into polymer micelles and vesicles...
Scheme 1: C–N bond formation under micellar catalyst conditions, no organic solvent involved. Adapted from re...
Scheme 2: Suzuki−Miyaura couplings with, or without, ppm Pd. Conditions: ArI 0.5 mmol 3a, Ar’B(OH)2 (0.75–1.0...
Figure 2: PQS (4a), PQS attached proline catalyst 4b. Adapted from reference [26]. Copyright 2012 American Chemic...
Figure 3: 3a) Schematic representation of a Pickering emulsion with the enzyme in the water phase (i), or wit...
Scheme 3: Cascade reaction with GOx and Myo. Adapted from reference [82].
Figure 4: Cross-linked polymersomes with Cu(OTf)2 catalyst. Reprinted with permission from [15].
Figure 5: Schematic representation of enzymatic polymerization in polymersomes. (A) CALB in the aqueous compa...
Figure 6: Representation of DSN-G0. Reprinted with permission from [100].
Figure 7: The multivalent esterase dendrimer 5 catalyzes the hydrolysis of 8-acyloxypyrene 1,3,6-trisulfonate...
Figure 8: Conversion of 4-NP in five successive cycles of reduction, catalyzed by Au@citrate, Au@PEG and Au@P...
A non-canonical peptide synthetase adenylates 3-methyl-2-oxovaleric acid for auriculamide biosynthesis
- Daniel Braga,
- Dirk Hoffmeister and
- Markus Nett
Beilstein J. Org. Chem. 2016, 12, 2766–2770, doi:10.3762/bjoc.12.274
- with gramicidin synthetase from Bacillus brevis led to the identification of ten positions within an A domain (PheA), collectively referred to as nonribosomal code [14], that control substrate selectivity. Further research started to establish a relationship between this code and structural
Graphical Abstract
Figure 1: Herpetosiphon natural products auriculamide (1) and siphonazole (2).
Figure 2: Organisation of the aul biosynthetic gene cluster. Circles illustrate the domain architecture of th...
Figure 3: Testing of AulA (A1-A2-KR-PCP) and a truncated variant (A2-KR-PCP) in the ATP-[32P]pyrophosphate ex...
Organic chemistry meets polymers, nanoscience, therapeutics and diagnostics
- Vincent M. Rotello
Beilstein J. Org. Chem. 2016, 12, 1638–1646, doi:10.3762/bjoc.12.161
- complex behaves differently than either of the two components. A prime example of this synergy is when we showed that nanoparticle–enzyme complexes showed altered substrate selectivity [51], with the particle dictating the enzyme kinetics by acting as a "filter" for substrate and product [47]. Another
Graphical Abstract
Figure 1: Flavoenzyme model system for determining the role of aromatic stacking in flavin redox processes. R...
Figure 2: Recognition element-functionalized polymers for 'plug and play' modification and self-assembly.
Figure 3: Recognition-mediated assembly of nanoparticle–polymer constructs. Reproduced from [24].
Figure 4: Cytosolic delivery of GFP to cells using nanoparticle-stabilized nanocapsules. Adapted with permiss...
Figure 5: Rapid determination of therapeutic mechanisms using three-channel nanoparticle fluorescent protein ...
Biosynthesis of oxygen and nitrogen-containing heterocycles in polyketides
- Franziska Hemmerling and
- Frank Hahn
Beilstein J. Org. Chem. 2016, 12, 1512–1550, doi:10.3762/bjoc.12.148
- . himastatinicus, both, glutarimides and lactones were obtained from respective substrate conversions. Thus, the domains can be seen as functionally equivalent [133]. Supported by kinetic analyses and mutational studies it was shown that B-domains, neither have an influence on the substrate selectivity nor on the
Graphical Abstract
Scheme 1: Schematic description of the cyclisation reaction catalysed by TE domains. In most cases, the nucle...
Scheme 2: Mechanisms for the formation of oxygen heterocycles. The degree of substitution can differ from tha...
Scheme 3: Pyran-ring formation in pederin (24) biosynthesis. Incubation of recombinant PedPS7 with substrate ...
Scheme 4: The domain AmbDH3 from ambruticin biosynthesis catalyses the dehydration of 25 and subsequent cycli...
Scheme 5: SalBIII catalyses dehydration of 29 and subsequent cyclisation to tetrahydropyran 30 [18].
Figure 1: All pyranonaphtoquinones contain either the naphtha[2,3-c]pyran-5,10-dione (32) or the regioisomeri...
Scheme 6: Pyran-ring formation in actinorhodin (34) biosynthesis. DNPA: 4-dihydro-9-hydroxy-1-methyl-10-oxo-3H...
Scheme 7: Pyran formation in granaticin (36) biosynthesis. DNPA: 4-dihydro-9-hydroxy-1-methyl-10-oxo-3H-napht...
Scheme 8: Pyran formation in alnumycin (37) biosynthesis. Adapted from [21].
Scheme 9: Biosynthesis of pseudomonic acid A (61). The pyran ring is initially formed in 57 after dehydrogena...
Scheme 10: Epoxidation–cyclisation leads to the formation of the tetrahydropyran ring in the western part of t...
Scheme 11: a) Nonactin (70) is formed from heterodimers of (−)(+)-dimeric nonactic acid and (+)(−)-dimeric non...
Figure 2: Pamamycins (73) are macrodiolide antibiotics containing three tetrahydrofuran moieties, which are a...
Scheme 12: A PS domain homolog in oocydin A (76) biosynthesis is proposed to catalyse furan formation via an o...
Scheme 13: Mechanism of oxidation–furan cyclisation by AurH, which converts (+)-deoxyaureothin (77) into (+)-a...
Scheme 14: Leupyrrin A2 (80) and the proposed biosynthesis of its furylidene moiety [69,70].
Scheme 15: Asperfuranone (93) biosynthesis, adapted from [75].
Figure 3: The four major aflatoxins produced by Aspergilli are the types B1, B2, G1 and G2 (94–97). In the di...
Scheme 16: Overview on aflatoxin B1 (94) biosynthesis. HOMST = 11-hydroxy-O-methylsterigmatocystin [78,79,82-106].
Scheme 17: A zipper mechanism leads to the formation of oxygen heterocycles in monensin biosynthesis [109-111].
Scheme 18: Formation of the 2,6-dioxabicyclo[3.2.1]octane (DBO) ring system in aurovertin B (118) biosynthesis ...
Figure 4: Structures of the epoxide-containing polyketides epothilone A (119) and oleandomycin (120) [123-125].
Scheme 19: Structures of phoslactomycin B (121) (a) and jerangolid A (122) (b). The heterocycle-forming steps ...
Scheme 20: a) Structures of rhizoxin (130) and cycloheximide (131). Model for the formation of δ-lactones (b) ...
Scheme 21: EncM catalyses a dual oxidation sequence and following processing of the highly reactive intermedia...
Figure 5: Mesomeric structures of tetronates [138,139].
Figure 6: Structures of tetronates for which gene clusters have been sequenced. The tetronate moiety is shown...
Scheme 22: Conserved steps for formation and processing in several 3-acyl-tetronate biosynthetic pathways were...
Scheme 23: In versipelostatin A (153) biosynthesis, VstJ is a candidate enzyme for catalysing the [4 + 2] cycl...
Scheme 24: a) Structures of some thiotetronate antibiotics. b) Biosynthesis of thiolactomycin (165) as propose...
Scheme 25: Aureusidine synthase (AS) catalyses phenolic oxidation and conjugate addition of chalcones leading ...
Scheme 26: a) Oxidative cyclisation is a key step in the biosynthesis of spirobenzofuranes 189, 192 and 193. b...
Scheme 27: A bicyclisation mechanism forms a β-lactone and a pyrrolidinone and removes the precursor from the ...
Scheme 28: Spontaneous cyclisation leads to off-loading of ebelactone A (201) from the PKS machinery [163].
Scheme 29: Mechanisms for the formation of nitrogen heterocycles.
Scheme 30: Biosynthesis of highly substituted α-pyridinones. a) Feeding experiments confirmed the polyketide o...
Scheme 31: Acridone synthase (ACS) catalyses the formation of 1,3-dihydroxy-N-methylacridone (224) by condensa...
Scheme 32: A Dieckmann condensation leads to the formation of a 3-acyl-4-hydroxypyridin-2-one 227 and removes ...
Scheme 33: a) Biosynthesis of the pyridinone tenellin (234). b) A radical mechanism was proposed for the ring-...
Scheme 34: a) Oxazole-containing PKS–NRPS-derived natural products oxazolomycin (244) and conglobatin (245). b...
Scheme 35: Structure of tetramic acids 251 (a) and major tautomers of 3-acyltetramic acids 252a–d (b). Adapted...
Scheme 36: Equisetin biosynthesis. R*: terminal reductive domain. Adapted from [202].
Scheme 37: a) Polyketides for which a similar biosynthetic logic was suggested. b) Pseurotin A (256) biosynthe...
Figure 7: Representative examples of PTMs with varying ring sizes and oxidation patterns [205,206].
Scheme 38: Ikarugamycin biosynthesis. Adapted from [209-211].
Scheme 39: Tetramate formation in pyrroindomycin aglycone (279) biosynthesis [213-215].
Scheme 40: Dieckmann cyclases catalyse tetramate or 2-pyridone formation in the biosynthesis of, for example, ...
Learning from the unexpected in life and DNA self-assembly
- Jennifer M. Heemstra
Beilstein J. Org. Chem. 2015, 11, 2713–2720, doi:10.3762/bjoc.11.292
- potential to provide throughput on the order of 105–106 samples per day [18]. We envisioned that aptamers could serve as powerful recognition elements for fluorescence-based high-throughput enantiopurity measurement, and the first key element to our approach was the concept of reciprocal chiral substrate
- selectivity. According to this principle, aptamers having the same sequence, but synthesized from opposite enantiomers of DNA, will bind to opposite enantiomers of a target molecule with identical affinity and selectivity [19]. The second key element to our approach was the ability of DNA structure-switching
Graphical Abstract
Figure 1: The common thread that is woven throughout our research program is the utilization of nucleic acid ...
Figure 2: Split aptamers use molecular recognition to drive the assembly of two DNA strands. Placing reactive...
Figure 3: Split aptamer ligation can be used to construct an enzyme-linked assay for small-molecule detection...
Figure 4: (a) In contrast to the more typical hairpin aptamer structure, we hypothesized that the three-way j...
Figure 5: Structure switching biosensors convert the presence of a target into a dose-dependent fluorescence ...
Figure 6: The author intensely focused on climbing the boulder problem “The Angler” during a research group o...
Dicarboxylic esters: Useful tools for the biocatalyzed synthesis of hybrid compounds and polymers
- Ivan Bassanini,
- Karl Hult and
- Sergio Riva
Beilstein J. Org. Chem. 2015, 11, 1583–1595, doi:10.3762/bjoc.11.174
- second step for polymerisation or crosslinking without the lipase. By exploiting the substrate selectivity of lipases it is possible to obtain well-defined telechelics in a one-pot, or even one-step reaction. In 1997 Uyama et al. were the first to produce telechelic polyesters from the monomers divinyl
Graphical Abstract
Scheme 1: Activated derivatives of dicarboxylic acids.
Figure 1: Example of natural compounds selectively acylated with dicarboxylic esters.
Figure 2: C6-dicarboxylic acid diesters derivatives of NAG-thiazoline.
Figure 3: Sylibin dimers obtained by CAL-B catalyzed trans-acylation reactions.
Scheme 2: Biocatalyzed synthesis of paclitaxel derivatives.
Figure 4: 5-Fluorouridine derivatives obtained by CAL-B catalysis.
Scheme 3: Biocatalyzed synthesis of hybrid diesters 17 and 18.
Scheme 4: Hybrid derivatives of sylibin.
Figure 5: Bolaamphiphilic molecules containing (L)- and/or (D)-isoascorbic acid moieties.
Figure 6: Doxorubicin (29) trapped in a polyester made of glycolate, sebacate and 1,4-butandiol units.
Figure 7: Polyesters containing functionalized pentofuranose derivatives.
Figure 8: Polyesters containing disulfide moieties.
Figure 9: Polyesters containing epoxy moieties.
Figure 10: Biocatalyzed synthesis of polyesters containing glycerol.
Figure 11: Iataconic (34) and malic (35) acid.
Figure 12: Oxidized poly(hexanediol-2-mercaptosuccinate) polymer.
Figure 13: C-5-substituted isophthalates.
Figure 14: Curcumin-based polyesters.
Figure 15: Silylated polyesters.
Figure 16: Polyesters containing reactive ether moieties.
Figure 17: Polyesters obtained by CAL-B-catalyzed condensation of dicarboxylic esters and N-substituted dietha...
Figure 18: Polyesters comprising mexiletine (38) moieties.
Figure 19: Poly(amide-co-ester)s comprising a terminal hydroxy moiety.
Figure 20: Polymer comprising α-oxydiacid moieties.
Figure 21: Telechelics with methacrylate ends.
Figure 22: Telechelics with allyl-ether ends.
Figure 23: Telechelics with ends functionalized as epoxides.
Biosynthesis of rare hexoses using microorganisms and related enzymes
- Zijie Li,
- Yahui Gao,
- Hideki Nakanishi,
- Xiaodong Gao and
- Li Cai
Beilstein J. Org. Chem. 2013, 9, 2434–2445, doi:10.3762/bjoc.9.281
- biosynthesis and enzymatic production of rare hexoses, including ketohexoses, aldohexoses, and sugar alcohols (hexitols). To improve the production of these rare sugars, strategies for enhancing the catalytic efficiency and/or substrate selectivity of related enzymes are also discussed. Review I. Biosynthesis
Graphical Abstract
Scheme 1: Synthesis of D-tagatose from D-galactose using L-arabinose isomerase.
Scheme 2: Synthesis of D-psicose from D-fructose using D-tagatose 3-epimerase/D-psicose 3-epimerase.
Figure 1: The active site in D-psicose 3-epimerase (DPEase) in the presence of D-fructose, showing the metal ...
Scheme 3: Enzymatic synthesis of D-psicose using aldolase FucA.
Scheme 4: Proposed pathway of the D-sorbose synthesis from galactitol or L-glucitol.
Scheme 5: Simultaneous enzymatic synthesis of D-sorbose and D-psicose.
Scheme 6: Biosynthesis of L-tagatose.
Scheme 7: Preparative-scale synthesis of L-tagatose and L-fructose using aldolase.
Scheme 8: Biosynthesis of L-fructose.
Scheme 9: Preparative-scale synthesis of L-fructose using aldolase RhaD.
Scheme 10: Chemoenzymatically synthesis of 1-deoxy-L-fructose [8].
Scheme 11: Potential enzymes (isomerases) for the bioconversion of D-psicose to D-allose.
Scheme 12: Three-step bioconversion of D-glucose to D-allose.
Scheme 13: Biosynthesis of L-glucose.
Scheme 14: Enzymatic synthesis of L-talose and D-gulose.
Scheme 15: Enzymatic synthesis of L-galactose.
Scheme 16: Enzymatic synthesis of L-fucose.
Scheme 17: Synthesis of allitol from D-fructose using a multi-enzyme system.
Scheme 18: Biosynthesis of D-talitol via C-2 reduction of rare sugars.
Scheme 19: Biosynthesis of L-sorbitol via C-2 reduction of rare sugars.
Utilizing the σ-complex stability for quantifying reactivity in nucleophilic substitution of aromatic fluorides
- Magnus Liljenberg,
- Tore Brinck,
- Tobias Rein and
- Mats Svensson
Beilstein J. Org. Chem. 2013, 9, 791–799, doi:10.3762/bjoc.9.90
- structure of the σ-complex resembles the rate-limiting transition state and that this provides a rationale for the observed correlations between the SS and the reaction rate. Keywords: computational; DFT; nucleophilic aromatic substitution; reactivity; substrate selectivity; reactive intermediates
Graphical Abstract
Figure 1: The structures investigated in the amination of heterocyclic and carbocyclic derivatives (series A ...
Figure 2: –log k as a function of SS in water for series A and B.
Figure 3: The structures investigated in the methoxylation of polychlorofluorobenzene derivatives (series C) ...
Figure 4: −log k as a function of SS in methanol for series C.
Figure 5: Optimized geometries, relative energies, and imaginary frequencies for the transition states and th...
