Search for "drug discovery" in Full Text gives 279 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122
Graphical Abstract
Scheme 1: Mn-catalyzed late-stage fluorination of sclareolide (1) and complex steroid 3.
Figure 1: Proposed reaction mechanism of C–H fluorination by a manganese porphyrin catalyst.
Scheme 2: Late-stage radiofluorination of biologically active complex molecules.
Figure 2: Proposed mechanism of C–H radiofluorination.
Scheme 3: Late-stage C–H azidation of bioactive molecules. a1.5 mol % of Mn(TMP)Cl (5) was used. bMethyl acet...
Figure 3: Proposed reaction mechanism of manganese-catalyzed C–H azidation.
Scheme 4: Mn-catalyzed late-stage C–H azidation of bioactive molecules via electrophotocatalysis. a2.5 mol % ...
Figure 4: Proposed reaction mechanism of electrophotocatalytic azidation.
Scheme 5: Manganaelectro-catalyzed late-stage azidation of bioactive molecules.
Figure 5: Proposed reaction pathway of manganaelectro-catalyzed late-stage C–H azidation.
Scheme 6: Mn-catalyzed late-stage amination of bioactive molecules. a3 Å MS were used. Protonation with HBF4⋅...
Figure 6: Proposed mechanism of manganese-catalyzed C–H amination.
Scheme 7: Mn-catalyzed C–H methylation of heterocyclic scaffolds commonly found in small-molecule drugs. aDAS...
Scheme 8: Examples of late-stage C–H methylation of bioactive molecules. aDAST activation. bFor insoluble sub...
Scheme 9: A) Mn-catalyzed late-stage C–H alkynylation of peptides. B) Intramolecular late-stage alkynylative ...
Figure 7: Proposed reaction mechanism of Mn(I)-catalyzed C–H alkynylation.
Scheme 10: Late-stage Mn-catalyzed C–H allylation of peptides and bioactive motifs.
Scheme 11: Intramolecular C–H allylative cyclic peptide formation.
Scheme 12: Late-stage C–H glycosylation of tryptophan analogues.
Scheme 13: Late-stage C–H glycosylation of tryptophan-containing peptides.
Scheme 14: Late-stage C–H alkenylation of tryptophan-containing peptides.
Scheme 15: A) Late-stage C–H macrocyclization of tryptophan-containing peptides and B) traceless removal of py...
Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112
Graphical Abstract
Figure 1: Some examples of natural products and drugs containing quaternary carbon centers.
Scheme 1: Simplified mechanism for olefin hydrofunctionalization using an electrophilic transition metal as a...
Scheme 2: Selected examples of quaternary carbon centers formed by the intramolecular hydroalkylation of β-di...
Scheme 3: Control experiments and the proposed mechanism for the Pd(II)-catalyzed intermolecular hydroalkylat...
Scheme 4: Intermolecular olefin hydroalkylation of less reactive ketones under Pd(II) catalysis using HCl as ...
Scheme 5: A) Selected examples of Pd(II)-mediated quaternary carbon center synthesis by intermolecular hydroa...
Scheme 6: Selected examples of quaternary carbon center synthesis by gold(III) catalysis. This is the first r...
Scheme 7: Selected examples of inter- (A) and intramolecular (B) olefin hydroalkylations promoted by a silver...
Scheme 8: A) Intermolecular hydroalkylation of N-alkenyl β-ketoamides under Au(I) catalysis in the synthesis ...
Scheme 9: Asymmetric pyrrolidine synthesis through intramolecular hydroalkylation of α-substituted N-alkenyl ...
Scheme 10: Proposed mechanism for the chiral gold(I) complex promotion of the intermolecular olefin hydroalkyl...
Scheme 11: Selected examples of carbon quaternary center synthesis by gold and evidence of catalytic system pa...
Scheme 12: Synthesis of a spiro compound via an aza-Michael addition/olefin hydroalkylation cascade promoted b...
Scheme 13: A selected example of quaternary carbon center synthesis using an Fe(III) salt as a catalyst for th...
Scheme 14: Intermolecular hydroalkylation catalyzed by a cationic iridium complex (Fuji (2019) [47]).
Scheme 15: Generic example of an olefin hydrofunctionalization via MHAT (Shenvi (2016) [51]).
Scheme 16: The first examples of olefin hydrofunctionalization run under neutral conditions (Mukaiyama (1989) [56]...
Scheme 17: A) Aryl olefin dimerization catalyzed by vitamin B12 and triggered by HAT. B) Control experiment to...
Scheme 18: Generic example of MHAT diolefin cycloisomerization and possible competitive pathways. Shenvi (2014...
Scheme 19: Selected examples of the MHAT-promoted cycloisomerization reaction of unactivated olefins leading t...
Scheme 20: Regioselective carbocyclizations promoted by an MHAT process (Norton (2008) [76]).
Scheme 21: Selected examples of quaternary carbon centers synthetized via intra- (A) and intermolecular (B) MH...
Scheme 22: A) Proposed mechanism for the Fe(III)/PhSiH3-promoted radical conjugate addition between olefins an...
Scheme 23: Examples of cascade reactions triggered by HAT for the construction of trans-decalin backbone uniti...
Scheme 24: A) Selected examples of the MHAT-promoted radical conjugate addition between olefins and p-quinone ...
Scheme 25: A) MHAT triggered radical conjugate addition/E1cB/lactonization (in some cases) cascade between ole...
Scheme 26: A) Spirocyclization promoted by Fe(III) hydroalkylation of unactivated olefins. B) Simplified mecha...
Scheme 27: A) Selected examples of the construction of a carbon quaternary center by the MHAT-triggered radica...
Scheme 28: Hydromethylation of unactivated olefins under iron-mediated MHAT (Baran (2015) [95]).
Scheme 29: The hydroalkylation of unactivated olefins via iron-mediated reductive coupling with hydrazones (Br...
Scheme 30: Selected examples of the Co(II)-catalyzed bicyclization of dialkenylarenes through the olefin hydro...
Scheme 31: Proposed mechanism for the bicyclization of dialkenylarenes triggered by a MHAT process (Vanderwal ...
Scheme 32: Enantioconvergent cross-coupling between olefins and tertiary halides (Fu (2018) [108]).
Scheme 33: Proposed mechanism for the Ni-catalyzed cross-coupling reaction between olefins and tertiary halide...
Scheme 34: Proposed catalytic cycles for a MHAT/Ni cross-coupling reaction between olefins and halides (Shenvi...
Scheme 35: Selected examples of the hydroalkylation of olefins by a dual catalytic Mn/Ni system (Shenvi (2019) ...
Scheme 36: A) Selected examples of quaternary carbon center synthesis by reductive atom transfer; TBC: 4-tert-...
Scheme 37: A) Selected examples of quaternary carbon centers synthetized by radical addition to unactivated ol...
Scheme 38: A) Selected examples of organophotocatalysis-mediated radical polyene cyclization via a PET process...
Scheme 39: A) Sc(OTf)3-mediated carbocyclization approach for the synthesis of vicinal quaternary carbon cente...
Scheme 40: Scope of the Lewis acid-catalyzed methallylation of electron-rich styrenes. Method A: B(C6F5)3 (5.0...
Scheme 41: The proposed mechanism for styrene methallylation (Oestreich (2019) [123]).
Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86
Graphical Abstract
Scheme 1: General strategy for the enantioselective synthesis of N-containing heterocycles from N-tert-butane...
Scheme 2: Methodologies for condensation of aldehydes and ketones with tert-butanesulfinamides (1).
Scheme 3: Transition models for cis-aziridines and trans-aziridines.
Scheme 4: Mechanism for the reduction of N-tert-butanesulfinyl imines.
Scheme 5: Transition models for the addition of organomagnesium and organolithium compounds to N-tert-butanes...
Scheme 6: Synthesis of 2,2-dibromoaziridines 15 from aldimines 14 and bromoform, and proposed non-chelation-c...
Scheme 7: Diastereoselective synthesis of aziridines from tert-butanesulfinyl imines.
Scheme 8: Synthesis of vinylaziridines 22 from aldimines 14 and 1,3-dibromopropene 23, and proposed chelation...
Scheme 9: Synthesis of vinylaziridines 27 from aldimines 14 and α-bromoesters 26, and proposed transition sta...
Scheme 10: Synthesis of 2-chloroaziridines 28 from aldimines 14 and dichloromethane, and proposed transition s...
Scheme 11: Synthesis of cis-vinylaziridines 30 and 31 from aldimines 14 and bromomethylbutenolide 29.
Scheme 12: Synthesis of 2-chloro-2-aroylaziridines 36 and 32 from aldimines 14, arylnitriles 34, and silyldich...
Scheme 13: Synthesis of trifluoromethylaziridines 39 and proposed transition state of the aziridination.
Scheme 14: Synthesis of aziridines 42 and proposed state transition.
Scheme 15: Synthesis of 1-substituted 2-azaspiro[3.3]heptanes, 1-phenyl-2-azaspiro[3.4]octane and 1-phenyl-2-a...
Scheme 16: Synthesis of 1-substituted 2,6-diazaspiro[3.3]heptanes 48 from chiral imines 14 and 1-Boc-azetidine...
Scheme 17: Synthesis of β-lactams 52 from chiral imines 14 and dimethyl malonate (49).
Scheme 18: Synthesis of spiro-β-lactam 57 from chiral (RS)-N-tert-butanesulfinyl isatin ketimine 53 and ethyl ...
Scheme 19: Synthesis of β-lactam 60, a precursor of (−)-batzelladine D (61) and (−)-13-epi-batzelladine D (62)...
Scheme 20: Rhodium-catalyzed asymmetric synthesis of 3-substituted pyrrolidines 66 from chiral imine (RS)-63 a...
Scheme 21: Asymmetric synthesis of 1,3-disubstituted isoindolines 69 and 70 from chiral imine 67.
Scheme 22: Asymmetric synthesis of cis-2,5-disubstituted pyrrolidines 73 from chiral imine (RS)-71.
Scheme 23: Asymmetric synthesis of 3-hydroxy-5-substituted pyrrolidin-2-ones 77 from chiral imine (RS)-74.
Scheme 24: Asymmetric synthesis of 4-hydroxy-5-substituted pyrrolidin-2-ones 80 from chiral imines 79.
Scheme 25: Asymmetric synthesis of 3-pyrrolines 82 from chiral imines 14 and ethyl 4-bromocrotonate (81).
Scheme 26: Asymmetric synthesis of γ-amino esters 84, and tetramic acid derivative 86 from chiral imines (RS)-...
Scheme 27: Asymmetric synthesis of α-methylene-γ-butyrolactams 90 from chiral imines (Z,SS)-87 and ethyl 2-bro...
Scheme 28: Asymmetric synthesis of methylenepyrrolidines 92 from chiral imines (RS)-14 and 2-(trimethysilylmet...
Scheme 29: Synthesis of dibenzoazaspirodecanes from cyclic N-tert-butanesulfinyl imines.
Scheme 30: Stereoselective synthesis of cyclopenta[c]proline derivatives 103 from β,γ-unsaturated α-amino acid...
Scheme 31: Stereoselective synthesis of alkaloids (−)-angustureine (107) and (−)-cuspareine (108).
Scheme 32: Stereoselective synthesis of alkaloids (−)-pelletierine (112) and (+)-coniine (117).
Scheme 33: Synthesis of piperidine alkaloids (+)-dihydropinidine (122a), (+)-isosolenopsin (122b) and (+)-isos...
Scheme 34: Stereoselective synthesis of the alkaloids(+)-sedamine (125) from chiral imine (SS)-119.
Scheme 35: Stereoselective synthesis of trans-5-hydroxy-6-substituted-2-piperidinones 127 and 129 from chiral ...
Scheme 36: Stereoselective synthesis of trans-5-hydroxy-6-substituted ethanone-2-piperidinones 132 from chiral...
Scheme 37: Stereoselective synthesis of trans-3-benzyl-5-hydroxy-6-substituted-2-piperidinones 136 from chiral...
Scheme 38: Stereoselective synthesis of trans-5-hydroxy-6-substituted 2-piperidinones 139 from chiral imine 138...
Scheme 39: Stereoselective synthesis of ʟ-hydroxypipecolic acid 145 from chiral imine 144.
Scheme 40: Synthesis of 1-substituted isoquinolones 147, 149 and 151.
Scheme 41: Stereoselective synthesis of 3-substituted dihydrobenzo[de]isoquinolinones 154.
Scheme 42: Enantioselective synthesis of alkaloids (S)-1-benzyl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline (...
Scheme 43: Enantioselective synthesis of alkaloids (−)-cermizine B (171) and (+)-serratezomine E (172) develop...
Scheme 44: Stereoselective synthesis of (+)-isosolepnosin (177) and (+)-solepnosin (178) from homoallylamine d...
Scheme 45: Stereoselective synthesis of tetrahydroquinoline derivatives 184, 185 and 187 from chiral imines (RS...
Scheme 46: Stereoselective synthesis of pyridobenzofuran and pyridoindole derivatives 193 from homopropargylam...
Scheme 47: Stereoselective synthesis of 2-substituted 1,2,5,6-tetrahydropyridines 196 from chiral imines (RS)-...
Scheme 48: Stereoselective synthesis of 2-substituted trans-2,6-disubstituted piperidine 199 from chiral imine...
Scheme 49: Stereoselective synthesis of cis-2,6-disubstituted piperidines 200, and alkaloid (+)-241D, from chi...
Scheme 50: Stereoselective synthesis of 6-substituted piperidines-2,5-diones 206 and 1,7-diazaspiro[4.5]decane...
Scheme 51: Stereoselective synthesis of spirocyclic oxindoles 210 from chiral imines (RS)-53.
Scheme 52: Stereoselective synthesis of azaspiro compound 213 from chiral imine 211.
Scheme 53: Stereoselective synthesis of tetrahydroisoquinoline derivatives from chiral imines (RS)-214.
Scheme 54: Stereoselective synthesis of (−)-crispine A 223 from chiral imine (RS)-214.
Scheme 55: Synthesis of (−)-harmicine (228) using tert-butanesulfinamide through haloamide cyclization.
Scheme 56: Stereoselective synthesis of tetraponerines T1–T8.
Scheme 57: Stereoselective synthesis of phenanthroindolizidines 246a and (−)-tylophorine (246b), and phenanthr...
Scheme 58: Stereoselective synthesis of indoline, tetrahydroquinoline and tetrahydrobenzazepine derivatives 253...
Scheme 59: Stereoselective synthesis of (+)-epohelmin A (258) and (+)-epohelmin B (260) from aldimine (RS)-79.
Scheme 60: Stereoselective synthesis of (−)-epiquinamide (266) from chiral aldimine (SS)-261.
Scheme 61: Synthesis synthesis of (–)-hippodamine (273) and (+)-epi-hippodamine (272) using chiral sulfinyl am...
Scheme 62: Stereoselective synthesis of (+)-grandisine D (279) and (+)-amabiline (283).
Scheme 63: Stereoselective synthesis of (−)-epiquinamide (266) and (+)-swaisonine (291) from aldimine (SS)-126....
Scheme 64: Stereoselective synthesis of (+)-C(9a)-epi-epiquinamide (294).
Scheme 65: Stereoselective synthesis of (+)-lasubine II (298) from chiral aldimine (SS)-109.
Scheme 66: Stereoselective synthesis of (−)-epimyrtine (300a) and (−)-lasubine II (ent-302) from β-amino keton...
Scheme 67: Stereoselective synthesis of (−)-tabersonine (310), (−)-vincadifformine (311), and (−)-aspidospermi...
Scheme 68: Stereoselective synthesis of (+)-epohelmin A (258) and (+)-epohelmin B (260) from aldehyde 313 and ...
Scheme 69: Total synthesis of (+)-lysergic acid (323) from N-tert-butanesulfinamide (RS)-1.
Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82
Graphical Abstract
Figure 1: Tautomeric forms of biguanide.
Figure 2: Illustrations of neutral, monoprotonated, and diprotonated structures biguanide.
Figure 3: The main approaches for the synthesis of biguanides. The core structure is obtained via the additio...
Scheme 1: The three main preparations of biguanides from cyanoguanidine.
Scheme 2: Synthesis of butylbiguanide using CuCl2 [16].
Scheme 3: Synthesis of biguanides by the direct fusion of cyanoguanidine and amine hydrochlorides [17,18].
Scheme 4: Synthesis of ethylbiguanide and phenylbiguanide as reported by Smolka and Friedreich [14].
Scheme 5: Synthesis of arylbiguanides through the reaction of cyanoguanidine with anilines in water [19].
Scheme 6: Synthesis of aryl- and alkylbiguanides by adaptations of Cohn’s procedure [20,21].
Scheme 7: Microwave-assisted synthesis of N1-aryl and -dialkylbiguanides [22,23].
Scheme 8: Synthesis of aryl- and alkylbiguanides by trimethylsilyl activation [24,26].
Scheme 9: Synthesis of phenformin analogs by TMSOTf activation [27].
Scheme 10: Synthesis of N1-(1,2,4-triazolyl)biguanides [28].
Scheme 11: Synthesis of 2-guanidinobenzazoles by addition of ortho-substituted anilines to cyanoguanidine [30,32] and...
Scheme 12: Synthesis of 2,4-diaminoquinazolines by the addition of 2-cyanoaniline to cyanoguanidine and from 3...
Scheme 13: Reactions of anthranilic acid and 2-mercaptobenzoic acid with cyanoguanidine [24,36,37].
Scheme 14: Synthesis of disubstituted biguanides with Cu(II) salts [38].
Scheme 15: Synthesis of an N1,N2,N5-trisubstituted biguanide by fusion of an amine hydrochloride and 2-cyano-1...
Scheme 16: Synthesis of N1,N5-disubstituted biguanides by the addition of anilines to cyanoguanidine derivativ...
Scheme 17: Microwave-assisted additions of piperazine and aniline hydrochloride to substituted cyanoguanidines ...
Scheme 18: Synthesis of N1,N5-alkyl-substituted biguanides by TMSOTf activation [27].
Scheme 19: Additions of oxoamines hydrochlorides to dimethylcyanoguanidine [49].
Scheme 20: Unexpected cyclization of pyridylcyanoguanidines under acidic conditions [50].
Scheme 21: Example of industrial synthesis of chlorhexidine [51].
Scheme 22: Synthesis of symmetrical N1,N5-diarylbiguanides from sodium dicyanamide [52,53].
Scheme 23: Synthesis of symmetrical N1,N5-dialkylbiguanides from sodium dicyanamide [54-56].
Scheme 24: Stepwise synthesis of unsymmetrical N1,N5-trisubstituted biguanides from sodium dicyanamide [57].
Scheme 25: Examples for the synthesis of unsymmetrical biguanides [58].
Scheme 26: Examples for the synthesis of an 1,3-diaminobenzoquinazoline derivative by the SEAr cyclization of ...
Scheme 27: Major isomers formed by the SEAr cyclization of symmetric biguanides derived from 2- and 3-aminophe...
Scheme 28: Lewis acid-catalyzed synthesis of 8H-pyrrolo[3,2-g]quinazoline-2,4-diamine [63].
Scheme 29: Synthesis of [1,2,4]oxadiazoles by the addition of hydroxylamine to dicyanamide [49,64].
Scheme 30: Principle of “bisamidine transfer” and analogy between the reactions with N-amidinopyrazole and N-a...
Scheme 31: Representative syntheses of N-amidino-amidinopyrazole hydrochloride [68,69].
Scheme 32: First examples of biguanide syntheses using N-amidino-amidinopyrazole [66].
Scheme 33: Example of “biguanidylation” of a hydrazide substrate [70].
Scheme 34: Example for the synthesis of biguanides using S-methylguanylisothiouronium iodide as “bisamidine tr...
Scheme 35: Synthesis of N-substituted N1-cyano-S-methylisothiourea precursors.
Scheme 36: Addition routes on N1-cyano-S-methylisothioureas.
Scheme 37: Synthesis of an hydroxybiguanidine from N1-cyano-S-methylisothiourea [77].
Scheme 38: Synthesis of an N1,N2,N3,N4,N5-pentaarylbiguanide from the corresponding triarylguanidine and carbo...
Scheme 39: Reactions of N,N,N’,N’-tetramethylguanidine (TMG) with carbodiimides to synthesize hexasubstituted ...
Scheme 40: Microwave-assisted addition of N,N,N’,N’-tetramethylguanidine to carbodiimides [80].
Scheme 41: Synthesis of N1-aryl heptasubstituted biguanides via a one-pot biguanide formation–copper-catalyzed ...
Scheme 42: Formation of 1,2-dihydro-1,3,5-triazine derivatives by the reaction of guanidine with excess carbod...
Scheme 43: Plausible mechanism for the spontaneous cyclization of triguanides [82].
Scheme 44: a) Formation of mono- and disubstituted (iso)melamine derivatives by the reaction of biguanides and...
Scheme 45: Reactions of 2-aminopyrimidine with carbodiimides to synthesize 2-guanidinopyrimidines as “biguanid...
Scheme 46: Non-catalyzed alternatives for the addition of 2-aminopyrimidine derivatives to carbodiimides. A) h...
Scheme 47: Addition of guanidinomagnesium halides to substituted cyanamides [90].
Scheme 48: Microwave-assisted synthesis of [11C]metformin by the reaction of 11C-labelled dimethylcyanamide an...
Scheme 49: Formation of 4-amino-6-dimethylamino[1,3,5]triazin-2-ol through the reaction of Boc-guanidine and d...
Scheme 50: Formation of 1,3,5-triazine derivatives via the addition of guanidines to substituted cyanamides [92].
Scheme 51: Synthesis of biguanide by the reaction of O-alkylisourea and guanidine [93].
Scheme 52: Aromatic nucleophilic substitution of guanidine on 2-O-ethyl-1,3,5-triazine [95].
Scheme 53: Synthesis of N1,N2-disubstituted biguanides by the reaction of guanidine and thioureas in the prese...
Scheme 54: Cyclization reactions involving condensations of guanidine(-like) structures with thioureas [97,98].
Scheme 55: Condensations of guanidine-like structures with thioureas [99,100].
Scheme 56: Condensations of guanidines with S-methylisothioureas [101,102].
Scheme 57: Addition of 2-amino-1,3-diazaaromatics to S-alkylisothioureas [103,104].
Scheme 58: Addition of guanidines to 2-(methylsulfonyl)pyrimidines [105].
Scheme 59: An example of a cyclodesulfurization reaction to a fused 3,5-diamino-1,2,4-triazole [106].
Scheme 60: Ring-opening reactions of 1,3-diaryl-2,4-bis(arylimino)-1,3-diazetidines [107].
Scheme 61: Formation of 3,5-diamino-1,2,4-triazole derivatives via addition of hydrazines to 1,3-diazetidine-2...
Scheme 62: Formation of a biguanide via the addition of aniline to 1,2,4-thiadiazol-3,5-diamines, ring opening...
Figure 4: Substitution pattern of biguanides accessible by synthetic pathways a–h.
Beilstein J. Org. Chem. 2021, 17, 991–1000, doi:10.3762/bjoc.17.81
Graphical Abstract
Figure 1: Structures and numbering of berberine (1a), berberrubine (1b) and 9-O-aryl-substituted berberine de...
Scheme 1: Synthesis of 10-O-arylated berberine derivatives 5a–e.
Scheme 2: Cu2+-catalyzed demethylation of berberrubine (1b).
Figure 2: Temperature dependent emission spectra of derivatives 5a and 5d (c = 10 µM, with 0.25% v/v DMSO) in...
Figure 3: Photometric titration of 5a (A) and 5d (B) (cLigand = 20 μM) with ct DNA (1) in BPE buffer (cNa+ = ...
Figure 4: Fluorimetric titration of 5a (A) and 5d (B, cLigand = 20 μM) with ct DNA (1) in BPE buffer (cNa+ = ...
Figure 5: CD and LD spectra of ct DNA (1 and 2, cDNA = 20 μM; in BPE buffer: 10 mM, pH 7.0; with 5% v/v DMSO)...
Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77
Graphical Abstract
Scheme 1: General strategy for the synthesis of THPs.
Scheme 2: Developments towards the Prins cyclization.
Scheme 3: General stereochemical outcome of the Prins cyclization.
Scheme 4: Regioselectivity in the Prins cyclization.
Scheme 5: Mechanism of the oxonia-Cope reaction in the Prins cyclization.
Scheme 6: Cyclization of electron-deficient enantioenriched alcohol 27.
Scheme 7: Partial racemization through 2-oxonia-Cope allyl transfer.
Scheme 8: Partial racemization by reversible 2-oxonia-Cope rearrangement.
Scheme 9: Rychnovsky modification of the Prins cyclization.
Scheme 10: Synthesis of (−)-centrolobine and the C22–C26 unit of phorboxazole A.
Scheme 11: Axially selective Prins cyclization by Rychnovsky et al.
Scheme 12: Mechanism for the axially selectivity Prins cyclization.
Scheme 13: Mukaiyama aldol–Prins cyclization reaction.
Scheme 14: Application of the aldol–Prins reaction.
Scheme 15: Hart and Bennet's acid-promoted Prins cyclization.
Scheme 16: Tetrahydropyran core of polycarvernoside A as well as (−)-clavoslide A and D.
Scheme 17: Scheidt and co-workers’ route to tetrahydropyran-4-one.
Scheme 18: Mechanism for the Lewis acid-catalyzed synthesis of tetrahydropyran-4-one.
Scheme 19: Hoveyda and co-workers’ strategy for 2,6-disubstituted 4-methylenetetrahydropyran.
Scheme 20: Funk and Cossey’s ene-carbamates strategy.
Scheme 21: Yadav and Kumar’s cyclopropane strategy for THP synthesis.
Scheme 22: 2-Arylcylopropylmethanolin in centrolobine synthesis.
Scheme 23: Yadav and co-workers’ strategy for the synthesis of THP.
Scheme 24: Yadav and co-workers’ Prins–Ritter reaction sequence for 4-amidotetrahydropyran.
Scheme 25: Yadav and co-workers’ strategy to prelactones B, C, and V.
Scheme 26: Yadav and co-workers’ strategy for the synthesis of (±)-centrolobine.
Scheme 27: Loh and co-workers’ strategy for the synthesis of zampanolide and dactylolide.
Scheme 28: Loh and Chan’s strategy for THP synthesis.
Scheme 29: Prins cyclization of cyclohexanecarboxaldehyde.
Scheme 30: Prins cyclization of methyl ricinoleate (127) and benzaldehyde (88).
Scheme 31: AlCl3-catalyzed cyclization of homoallylic alcohol 129 and aldehyde 130.
Scheme 32: Martín and co-workers’ stereoselective approach for the synthesis of highly substituted tetrahydrop...
Scheme 33: Ene-IMSC strategy by Marko and Leroy for the synthesis of tetrahydropyran.
Scheme 34: Marko and Leroy’s strategy for the synthesis of tetrahydropyrans 146.
Scheme 35: Sakurai dimerization/macrolactonization reaction for the synthesis of cyanolide A.
Scheme 36: Hoye and Hu’s synthesis of (−)-dactyloide by intramolecular Sakurai cyclization.
Scheme 37: Minehan and co-workers’ strategy for the synthesis of THPs 157.
Scheme 38: Yu and co-workers’ allylic transfer strategy for the construction of tetrahydropyran 161.
Scheme 39: Reactivity enhancement in intramolecular Prins cyclization.
Scheme 40: Floreancig and co-workers’ Prins cyclization strategy to (+)-dactyloide.
Scheme 41: Panek and Huang’s DHP synthesis from crotylsilanes: a general strategy.
Scheme 42: Panek and Huang’s DHP synthesis from syn-crotylsilanes.
Scheme 43: Panek and Huang’s DHP synthesis from anti-crotylsilanes.
Scheme 44: Roush and co-workers’ [4 + 2]-annulation strategy for DHP synthesis [82].
Scheme 45: TMSOTf-promoted annulation reaction.
Scheme 46: Dobb and co-workers’ synthesis of DHP.
Scheme 47: BiBr3-promoted tandem silyl-Prins reaction by Hinkle et al.
Scheme 48: Substrate scope of Hinkle and co-workers’ strategy.
Scheme 49: Cho and co-workers’ strategy for 2,6 disubstituted 3,4-dimethylene-THP.
Scheme 50: Furman and co-workers’ THP synthesis from propargylsilane.
Scheme 51: THP synthesis from silyl enol ethers.
Scheme 52: Rychnovsky and co-workers’ strategy for THP synthesis from hydroxy-substituted silyl enol ethers.
Scheme 53: Li and co-workers’ germinal bissilyl Prins cyclization strategy to (−)-exiguolide.
Scheme 54: Xu and co-workers’ hydroiodination strategy for THP.
Scheme 55: Wang and co-workers’ strategy for tetrahydropyran synthesis.
Scheme 56: FeCl3-catalyzed synthesis of DHP from alkynylsilane alcohol.
Scheme 57: Martín, Padrón, and co-workers’ proposed mechanism of alkynylsilane Prins cyclization for the synth...
Scheme 58: Marko and co-workers’ synthesis of 2,6-anti-configured tetrahydropyran.
Scheme 59: Loh and co-workers’ strategy for 2,6-syn-tetrahydropyrans.
Scheme 60: Loh and co-workers’ strategy for anti-THP synthesis.
Scheme 61: Cha and co-workers’ strategy for trans-2,6-tetrahydropyran.
Scheme 62: Mechanism proposed by Cha et al.
Scheme 63: TiCl4-mediated cyclization to trans-THP.
Scheme 64: Feng and co-workers’ FeCl3-catalyzed Prins cyclization strategy to 4-hydroxy-substituted THP.
Scheme 65: Selectivity profile of the Prins cyclization under participation of an iron ligand.
Scheme 66: Sequential reactions involving Prins cyclization.
Scheme 67: Banerjee and co-workers’ strategy of Prins cyclization from cyclopropane carbaldehydes and propargy...
Scheme 68: Mullen and Gagné's (R)-[(tolBINAP)Pt(NC6F5)2][SbF6]2-catalyzed asymmetric Prins cyclization strateg...
Scheme 69: Yu and co-workers’ DDQ-catalyzed asymmetric Prins cyclization strategy to trisubstituted THPs.
Scheme 70: Lalli and Weghe’s chiral-Brønsted-acid- and achiral-Lewis-acid-promoted asymmetric Prins cyclizatio...
Scheme 71: List and co-workers’ iIDP Brønsted acid-promoted asymmetric Prins cyclization strategy.
Scheme 72: Zhou and co-workers’ strategy for chiral phosphoric acid (CPA)-catalyzed cascade Prins cyclization.
Scheme 73: List and co-workers’ approach for asymmetric Prins cyclization using chiral imidodiphosphoric acid ...
Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71
Graphical Abstract
Figure 1: Marketed drugs with acridine moiety.
Scheme 1: Synthesis of 4-arylacridinediones.
Scheme 2: Proposed mechanism for acridinedione synthesis.
Scheme 3: Synthesis of tetrahydrodibenzoacridinones.
Scheme 4: Synthesis of naphthoacridines.
Scheme 5: Plausible mechanism for naphthoacridines.
Figure 2: Benzoazepines based potent molecules.
Scheme 6: Synthesis of azepinone.
Scheme 7: Proposed mechanism for azepinone formation.
Scheme 8: Synthesis of benzoazulenen-1-one derivatives.
Scheme 9: Proposed mechanism for benzoazulene-1-one synthesis.
Figure 3: Indole-containing pharmacologically active molecules.
Scheme 10: Synthesis of functionalized indoles.
Scheme 11: Plausible mechanism for the synthesis of functionalized indoles.
Scheme 12: Synthesis of spirooxindoles.
Scheme 13: Synthesis of substituted spirooxindoles.
Scheme 14: Plausible mechanism for the synthesis of substituted spirooxindoles.
Scheme 15: Synthesis of pyrrolidinyl spirooxindoles.
Scheme 16: Proposed mechanism for pyrrolidinyl spirooxindoles.
Figure 4: Pyran-containing biologically active molecules.
Scheme 17: Synthesis of functionalized benzopyrans.
Scheme 18: Plausible mechanism for synthesis of benzopyran.
Scheme 19: Synthesis of indoline-spiro-fused pyran derivatives.
Scheme 20: Proposed mechanism for indoline-spiro-fused pyran.
Scheme 21: Synthesis of substituted naphthopyrans.
Figure 5: Marketed drugs with pyrrole ring.
Scheme 22: Synthesis of tetra-substituted pyrroles.
Scheme 23: Mechanism for silica-supported PPA-SiO2-catalyzed pyrrole synthesis.
Scheme 24: Synthesis of pyrrolo[1,10]-phenanthrolines.
Scheme 25: Proposed mechanism for pyrrolo[1,10]-phenanthrolines.
Figure 6: Marketed drugs and molecules containing pyrimidine and pyrimidinones skeletons.
Scheme 26: MWA-MCR pyrimidinone synthesis.
Scheme 27: Two proposed mechanisms for pyrimidinone synthesis.
Scheme 28: MWA multicomponent synthesis of dihydropyrimidinones.
Scheme 29: Proposed mechanism for dihydropyrimidinones.
Figure 7: Biologically active fused pyrimidines.
Scheme 30: MWA- MCR for the synthesis of pyrrolo[2,3-d]pyrimidines.
Scheme 31: Proposed mechanism for pyrrolo[2,3-d]pyrimidines.
Scheme 32: Synthesis of substituted pyrrolo[2,3-d]pyrimidine-2,4-diones.
Scheme 33: Probable pathway for pyrrolo[2,3-d]pyrimidine-2,4-diones.
Scheme 34: Synthesis of pyridopyrimidines.
Scheme 35: Plausible mechanism for the synthesis of pyridopyrimidines.
Scheme 36: Synthesis of dihydropyridopyrimidine and dihydropyrazolopyridine.
Scheme 37: Proposed mechanism for the formation of dihydropyridopyrimidine.
Scheme 38: Synthesis of thiopyrano[4,3-d]pyrimidines.
Scheme 39: Plausible mechanism for the synthesis of thiopyrano[4,3-d]pyrimidines.
Scheme 40: Synthesis of decorated imidazopyrimidines.
Scheme 41: Proposed mechanism for imidazopyrimidine synthesis.
Figure 8: Pharmacologically active molecules containing purine bases.
Scheme 42: Synthesis of aza-adenines.
Scheme 43: Synthesis of 5-aza-7-deazapurines.
Scheme 44: Proposed mechanism for deazapurines synthesis.
Figure 9: Biologically active molecules containing pyridine moiety.
Scheme 45: Synthesis of steroidal pyridines.
Scheme 46: Proposed mechanism for steroidal pyridine.
Scheme 47: Synthesis of N-alkylated 2-pyridones.
Scheme 48: Two possible mechanisms for pyridone synthesis.
Scheme 49: Synthesis of pyridone derivatives.
Scheme 50: Postulated mechanism for synthesis of pyridone.
Figure 10: Biologically active fused pyridines.
Scheme 51: Benzimidazole-imidazo[1,2-a]pyridines synthesis.
Scheme 52: Mechanism for the synthesis of benzimidazole-imidazo[1,2-a]pyridines.
Scheme 53: Synthesis of pyrazolo[3,4-b]pyridine-5-spirocycloalkanedione derivatives.
Scheme 54: Proposed mechanism for spiro-pyridines.
Scheme 55: Functionalized macrocyclane-fused pyrazolo[3,4-b]pyridine derivatives.
Scheme 56: Mechanism postulated for macrocyclane-fused pyrazolo[3,4-b]pyridine.
Scheme 57: Generation of pyrazolo[3,4-b]pyridines.
Scheme 58: Proposed mechanism for the synthesis of pyrazolo[3,4-b]pyridines.
Scheme 59: Proposed mechanism for the synthesis of azepinoindole.
Figure 11: Pharmaceutically important molecules with quinoline moiety.
Scheme 60: Povarov-mediated quinoline synthesis.
Scheme 61: Proposed mechanism for Povarov reaction.
Scheme 62: Synthesis of pyrazoloquinoline.
Scheme 63: Plausible mechanism for pyrazoloquinoline synthesis.
Figure 12: Quinazolinones as pharmacologically significant scaffolds.
Scheme 64: Four-component reaction for dihydroquinazolinone.
Scheme 65: Proposed mechanism for dihydroquinazolinones.
Scheme 66: Synthesis purine quinazolinone and PI3K-δ inhibitor.
Scheme 67: Synthesis of fused benzothiazolo/benzoimidazoloquinazolinones.
Scheme 68: Proposed mechanism for fused benzothiazolo/benzoimidazoloquinazolinones.
Scheme 69: On-water reaction for synthesis of thiazoloquinazolinone.
Scheme 70: Proposed mechanism for the thiazoloquinazolinone synthesis.
Scheme 71: β-Cyclodextrin-mediated synthesis of indoloquinazolinediones.
Scheme 72: Proposed mechanism for synthesis of indoloquinazolinediones.
Figure 13: Triazoles-containing marketted drugs and pharmacologically active molecules.
Scheme 73: Cu(I) DAPTA-catalyzed 1,2,3-triazole formation.
Scheme 74: Mechanism for Cu(I) DAPTA-catalyzed triazole formation.
Scheme 75: Synthesis of β-hydroxy-1,2,3-triazole.
Scheme 76: Proposed mechanism for synthesis of β-hydroxy-1,2,3-triazoles.
Scheme 77: Synthesis of bis-1,2,4-triazoles.
Scheme 78: Proposed mechanism for bis-1,2,4-triazoles synthesis.
Figure 14: Thiazole containing drugs.
Scheme 79: Synthesis of a substituted thiazole ring.
Scheme 80: Synthesis of pyrazolothiazoles.
Figure 15: Chromene containing drugs.
Scheme 81: Magnetic nanocatalyst-mediated aminochromene synthesis.
Scheme 82: Proposed mechanism for the synthesis of chromenes.
Beilstein J. Org. Chem. 2021, 17, 431–438, doi:10.3762/bjoc.17.39
Graphical Abstract
Scheme 1: Chemistry of the CF3 anion generated from HCF3. a) Decomposition of the trifluoromethyl anion to di...
Figure 1: Trifluoromethyl ketones. a) Hydrolysis of trifluoromethyl ketones. b) Selected examples of biologic...
Scheme 2: Trifluoromethylation of esters by HCF3 by a) Russell and Roques (1998), b) Prakash and co-workers (...
Scheme 3: Substrate scope of esters 1 for trifluoromethylation by HCF3 under the optimized conditions. aDeter...
Beilstein J. Org. Chem. 2021, 17, 319–324, doi:10.3762/bjoc.17.29
Graphical Abstract
Figure 1: Biologically active di- and tetrahydropyridazines.
Scheme 1: Recyclization of hydroxypyrrolines with hydrazine derivatives.
Scheme 2: Synthesis of tetrahydropyridazines 3.
Scheme 3: Synthesis of dihydropyridazines 4.
Scheme 4: Recyclization of hydroxypyrroline 1a with hydrazides 2d and 2e.
Scheme 5: A proposed mechanism for the recyclization of hydroxypyrrolines 1 with hydrazides 2.
Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25
Graphical Abstract
Scheme 1: Synthesis of 1,1-difluoro-2,3-dimethylcyclopropane (2).
Scheme 2: Cyclopropanation via dehydrohalogenation of chlorodifluoromethane.
Scheme 3: Difluorocyclopropanation of methylstyrene 7 using dibromodifluoromethane and zinc.
Scheme 4: Synthesis of difluorocyclopropanes from the reaction of dibromodifluoromethane and triphenylphosphi...
Scheme 5: Generation of difluorocarbene in a catalytic two-phase system and its addition to tetramethylethyle...
Scheme 6: The reaction of methylstyrene 7 with chlorodifluoromethane (11) in the presence of a tetraarylarson...
Scheme 7: Pyrolysis of sodium chlorodifluoroacetate (12) in refluxing diglyme in the presence of alkene 13.
Scheme 8: Synthesis of boron-substituted gem-difluorocyclopropanes 16.
Scheme 9: Addition of sodium bromodifluoroacetate (17) to alkenes.
Scheme 10: Addition of sodium bromodifluoroacetate (17) to silyloxy-substituted cyclopropanes 20.
Scheme 11: Synthesis of difluorinated nucleosides.
Scheme 12: Addition of butyl acrylate (26) to difluorocarbene generated from TFDA (25).
Scheme 13: Addition of difluorocarbene to propargyl esters 27 and conversion of the difluorocyclopropenes 28 t...
Scheme 14: The generation of difluorocyclopropanes using MDFA 30.
Scheme 15: gem-Difluorocyclopropanation of styrene (32) using difluorocarbene generated from TMSCF3 (31) under...
Scheme 16: Synthesis of a gem-difluorocyclopropane derivative using HFPO (41) as a source of difluorocarbene.
Scheme 17: Cyclopropanation of (Z)-2-butene in the presence of difluorodiazirine (44).
Scheme 18: The cyclopropanation of 1-octene (46) using Seyferth's reagent (45) as a source of difluorocarbene.
Scheme 19: Alternative approaches for the difluorocarbene synthesis from trimethyl(trifluoromethyl)tin (48).
Scheme 20: Difluorocyclopropanation of cyclohexene (49).
Scheme 21: Synthesis of difluorocyclopropane derivative 53 using bis(trifluoromethyl)cadmium (51) as the diflu...
Scheme 22: Addition of difluorocarbene generated from tris(trifluoromethyl)bismuth (54).
Scheme 23: Addition of a stable (trifluoromethyl)zinc reagent to styrenes.
Scheme 24: The preparation of 2,2-difluorocyclopropanecarboxylic acids of type 58.
Scheme 25: Difluorocyclopropanation via Michael cyclization.
Scheme 26: Difluorocyclopropanation using N-acylimidazolidinone 60.
Scheme 27: Difluorocyclopropanation through the cyclization of phenylacetonitrile (61) and 1,2-dibromo-1,1-dif...
Scheme 28: gem-Difluoroolefins 64 for the synthesis of functionalized cyclopropanes 65.
Scheme 29: Preparation of aminocyclopropanes 70.
Scheme 30: Synthesis of fluorinated methylenecyclopropane 74 via selenoxide elimination.
Scheme 31: Reductive dehalogenation of (1R,3R)-75.
Scheme 32: Synthesis of chiral monoacetates by lipase catalysis.
Scheme 33: Transformation of (±)-trans-81 using Rhodococcus sp. AJ270.
Scheme 34: Transformation of (±)-trans-83 using Rhodococcus sp. AJ270.
Scheme 35: Hydrogenation of difluorocyclopropenes through enantioselective hydrocupration.
Scheme 36: Enantioselective transfer hydrogenation of difluorocyclopropenes with a Ru-based catalyst.
Scheme 37: The thermal transformation of trans-1,2-dichloro-3,3-difluorocyclopropane (84).
Scheme 38: cis–trans-Epimerization of 1,1-difluoro-2,3-dimethylcyclopropane.
Scheme 39: 2,2-Difluorotrimethylene diradical intermediate.
Scheme 40: Ring opening of stereoisomers 88 and 89.
Scheme 41: [1,3]-Rearrangement of alkenylcyclopropanes 90–92.
Scheme 42: Thermolytic rearrangement of 2,2-difluoro-1-vinylcyclopropane (90).
Scheme 43: Thermal rearrangement for ethyl 3-(2,2-difluoro)-3-phenylcyclopropyl)acrylates 93 and 95.
Scheme 44: Possible pathways of the ring opening of 1,1-difluoro-2-vinylcyclopropane.
Scheme 45: Equilibrium between 1,1-difluoro-2-methylenecyclopropane (96) and (difluoromethylene)cyclopropane 97...
Scheme 46: Ring opening of substituted 1,1-difluoro-2,2-dimethyl-3-methylenecyclopropane 98.
Scheme 47: 1,1-Difluorospiropentane rearrangement.
Scheme 48: Acetolysis of (2,2-difluorocyclopropyl)methyl tosylate (104) and (1,1-difluoro-2-methylcyclopropyl)...
Scheme 49: Ring opening of gem-difluorocyclopropyl ketones 106 and 108 by thiolate nucleophiles.
Scheme 50: Hydrolysis of gem-difluorocyclopropyl acetals 110.
Scheme 51: Ring-opening reaction of 2,2-difluorocyclopropyl ketones 113 in the presence of ionic liquid as a s...
Scheme 52: Ring opening of gem-difluorocyclopropyl ketones 113a by MgI2-initiated reaction with diarylimines 1...
Scheme 53: Ring-opening reaction of gem-difluorocyclopropylstannanes 117.
Scheme 54: Preparation of 1-fluorovinyl vinyl ketone 123 and the synthesis of 2-fluorocyclopentenone 124. TBAT...
Scheme 55: Iodine atom-transfer ring opening of 1,1-difluoro-2-(1-iodoalkyl)cyclopropanes 125a–c.
Scheme 56: Ring opening of bromomethyl gem-difluorocyclopropanes 130 and formation of gem-difluoromethylene-co...
Scheme 57: Ring-opening aerobic oxidation reaction of gem-difluorocyclopropanes 132.
Scheme 58: Dibrominative ring-opening functionalization of gem-difluorocyclopropanes 134.
Scheme 59: The selective formation of (E,E)- and (E,Z)-fluorodienals 136 and 137 from difluorocyclopropyl acet...
Scheme 60: Proposed mechanism for the reaction of difluoro(methylene)cyclopropane 139 with Br2.
Scheme 61: Thermal rearrangement of F2MCP 139 and iodine by CuI catalysis.
Scheme 62: Synthesis of 2-fluoropyrroles 142.
Scheme 63: Ring opening of gem-difluorocyclopropyl ketones 143 mediated by BX3.
Scheme 64: Lewis acid-promoted ring-opening reaction of 2,2-difluorocyclopropanecarbonyl chloride (148).
Scheme 65: Ring-opening reaction of the gem-difluorocyclopropyl ketone 106 by methanolic KOH.
Scheme 66: Hydrogenolysis of 1,1-difluoro-3-methyl-2-phenylcyclopropane (151).
Scheme 67: Synthesis of monofluoroalkenes 157.
Scheme 68: The stereoselective Ag-catalyzed defluorinative ring-opening diarylation of 1-trimethylsiloxy-2,2-d...
Scheme 69: Synthesis of 2-fluorinated allylic compounds 162.
Scheme 70: Pd-catalyzed cross-coupling reactions of gem-difluorinated cyclopropanes 161.
Scheme 71: The (Z)-selective Pd-catalyzed ring-opening sulfonylation of 2-(2,2-difluorocyclopropyl)naphthalene...
Figure 1: Structures of zosuquidar hydrochloride and PF-06700841.
Scheme 72: Synthesis of methylene-gem-difluorocyclopropane analogs of nucleosides.
Figure 2: Anthracene-difluorocyclopropane hybrid derivatives.
Figure 3: Further examples of difluorcyclopropanes in modern drug discovery.
Beilstein J. Org. Chem. 2021, 17, 203–209, doi:10.3762/bjoc.17.20
Graphical Abstract
Scheme 1: Flow generation and transformation of 2H-azirines.
Scheme 2: Flow synthesis of 2H-azirines from vinyl azides. aThe solution of vinyl azide was re-introduced twi...
Scheme 3: Mixed flow-batch approach for the preparation of functionalized NH-aziridines from vinyl azides.
Beilstein J. Org. Chem. 2021, 17, 89–96, doi:10.3762/bjoc.17.9
Graphical Abstract
Figure 1: Medical compounds having a difluoromethyl group.
Scheme 1: Methods for the synthesis of ethers containing fluorine substituents.
Scheme 2: The previous work reported by Yagupol’skii et al.
Scheme 3: Intramolecular 1,4-addition of 2o.
Scheme 4: Proposed reaction mechanism.
Beilstein J. Org. Chem. 2020, 16, 2971–2982, doi:10.3762/bjoc.16.247
Graphical Abstract
Figure 1: Three different type of peptide-based fluorescent probes and their interaction with nucleic acids a...
Figure 2: A) Molecular structure of peptidic probe 1, Inset: HeLa cells incubated with peptide 1 (50 μM), sho...
Figure 3: A) Molecular structure of probe 2; B) fluorescence emission spectra for the titration of a 10 μM so...
Figure 4: A) Molecular structure of 3; B) fluorescence emission spectra for the titration of a 10 μM solution...
Figure 5: A) Molecular structure of 4 and 5; B) fluorescence spectra for the titration of a 0.5 μM solution o...
Figure 6: A) Molecular structure of 6; B) possible binding mode of pyrene termini of 6 to CB[8] according to ...
Figure 7: A) Molecular structure of peptidic probes 7 and 8; B) fluorescence emission spectra of probe 7 (5.0...
Figure 8: Top: Molecular structure of 9; bottom: A) fluorescence response of 9 (500 nM) upon addition of β-tr...
Figure 9: Top: Molecular structures of 10 and 11; bottom: A) fluorescence emission spectra of 10 (1.0 µM, λex...
Figure 10: A) Structure of two peptide amphiphiles 12 and 13; B) fluorescent spectra (λex = 400 nm) from a tit...
Figure 11: a) Molecular structure of peptide 14; b) the coordinate represents the states of sensor at differen...
Beilstein J. Org. Chem. 2020, 16, 2663–2670, doi:10.3762/bjoc.16.216
Graphical Abstract
Figure 1: The natural product piperine (1) is the inspiration for this work; the crystal structure is shown [14]....
Scheme 1: The attempted synthesis of 6 (a diastereoisomer of 2) via a one-step 1,2-difluorination reaction [24]. ...
Scheme 2: The attempted synthesis of 2 via a stepwise fluorination approach (ether series). THF = tetrahydrof...
Scheme 3: Synthesis of compound 2 via a stepwise fluorination approach (ester series). DIC = diisopropylcarbo...
Figure 2: Conformational analysis of 2 by DFT and NMR. The numbering scheme for NMR spins is given on structu...
Figure 3: Analog 2 has greater stability to UV light than does piperine (1).
Figure 4: Biological activity of piperine (1) and derivative 2. (a) Inihbition of AChE by 1 (IC50 >1000 μM) a...
Beilstein J. Org. Chem. 2020, 16, 2442–2447, doi:10.3762/bjoc.16.198
Graphical Abstract
Figure 1: Trifluoromethylation of aryl halides.
Figure 2: Scope of aryl iodides. Yields determined by 19F NMR spectroscopy and used ligand is given in parent...
Figure 3: Scope of heteroaryl iodides. Yields determined by 19F NMR spectroscopy and used ligand is given in ...
Figure 4: Time course of the trifluoromethylation reaction.
Figure 5: Proposed mechanism of the catalytic cycle.
Beilstein J. Org. Chem. 2020, 16, 2322–2331, doi:10.3762/bjoc.16.193
Graphical Abstract
Figure 1: Enaminones fused to heterocyclic moieties.
Scheme 1: Reported structure A of assayed compound [9] and its correct structure B.
Scheme 2: Known synthetic approaches to BTAs III.
Scheme 3: General synthetic approaches to enaminones I and II.
Scheme 4: Reported reactions of acylpyruvic acids or their esters IV with o-aminothiophenol (1a) [27,28].
Scheme 5: Plausible mechanism of the reaction of acylpyruvic acid 2a with o-aminothiophenol (1a) in the prese...
Scheme 6: The substrate scope of the optimized approach to BTAs 3a–n. Procedure: to a cooled to 0–5 °C stirri...
Scheme 7: The substrate scope of the optimized approach to compounds 4a–n. Procedure: to a stirring solution ...
Scheme 8: Plausible scheme of the formation of diketone 6.
Beilstein J. Org. Chem. 2020, 16, 2304–2313, doi:10.3762/bjoc.16.191
Graphical Abstract
Figure 1: Summary of the previous and present studies.
Scheme 1: Chan–Evans–Lam reaction of 4-trifluoromethylpyrimidin-2(1H)-one 1а with (het)aryl boronic acid 2b–w...
Scheme 2: Chan–Evans–Lam reaction of 4-trifluoromethylpyrimidin-2(1H)-one (1а) with (het)aryl- and alkenylbor...
Scheme 3: Chan–Evans–Lam reaction of pyrimidin-2(1H)-ones 1b–h with phenylboronic acid (2a).
Beilstein J. Org. Chem. 2020, 16, 1837–1852, doi:10.3762/bjoc.16.151
Graphical Abstract
Figure 1: A) Three types of the backbone amino acid structures that are included in protein translation: glyc...
Figure 2: The set of amino acids examined in this study.
Figure 3: Design of the model system.
Figure 4: Propagation of the C4-conformation into the values of the J coupling in the C2H–C3H2 fragments.
Figure 5: Preferred side-chain conformations according to the multiplicity data.
Figure 6: A) The basicity reduction from the introduction of the dipoles reflects the preferred conformation ...
Figure 7: The lipophilicity data of the model compounds.
Figure 8: The expectations regarding the amide-bond rotation preferences in 1–4.
Figure 9: The explanation for the difference in the rotation barriers in the diastereomeric (A), 4-(trifluoro...
Figure 10: A) The structures of difluorinated model compounds 5 and 6, and the fluorine-free reference 7. B) B...
Beilstein J. Org. Chem. 2020, 16, 1662–1682, doi:10.3762/bjoc.16.138
Graphical Abstract
Scheme 1: Schematic representation of the Pauson–Khand reaction.
Scheme 2: Substrates included in this review.
Scheme 3: Commonly accepted mechanism for the Pauson–Khand reaction.
Scheme 4: Regioselectivity of the PKR.
Scheme 5: Variability at the acetylenic and olefinic counterpart.
Scheme 6: Pauson–Khand reaction of fluoroolefinic enynes reported by the group of Ishizaki [46].
Scheme 7: PKR of enynes bearing fluorinated groups on the alkynyl moiety, reported by the group of Ishizaki [46]....
Scheme 8: Intramolecular PKR of 1,7-enynes reported by the group of Billard [47].
Scheme 9: Intramolecular PKR of 1,7-enynes reported by the group of Billard [48].
Scheme 10: Intramolecular PKR of 1,7-enynes by the group of Bonnet-Delpon [49]. Reaction conditions: i) Co(CO)8 (1...
Scheme 11: Intramolecular PKR of 1,6-enynes reported by the group of Ichikawa [50].
Scheme 12: Intramolecular Rh(I)-catalyzed PKR reported by the group of Hammond [52].
Scheme 13: Intramolecular PKR of allenynes reported by the group of Osipov [53].
Scheme 14: Intramolecular PKR of 1,7-enynes reported by the group of Osipov [53].
Scheme 15: Intramolecular PKR of fluorine-containing 1,6-enynes reported by the Konno group [54].
Scheme 16: Diastereoselective PKR with enantioenriched fluorinated enynes 34 [55].
Scheme 17: Intramolecular PKR reported by the group of Martinez-Solorio [56].
Scheme 18: Fluorine substitution at the olefinic counterpart.
Scheme 19: Synthesis of fluorinated enynes 37 [59].
Scheme 20: Fluorine-containing substrates in PKR [59].
Scheme 21: Pauson Khand reaction for fluorinated enynes by the Fustero group: scope and limitations [59].
Scheme 22: Synthesis of chloro and bromo analogues [59].
Scheme 23: Dimerization pathway [59].
Scheme 24: Synthesis of fluorine-containing N-tethered 1,7-enynes [61].
Scheme 25: Intramolecular PKR of chiral N-tethered fluorinated 1,7-enynes [61].
Scheme 26: Examples of further modifications to the Pauson−Khand adducts [61].
Scheme 27: Asymmetric synthesis the fluorinated enynes 53.
Scheme 28: Intramolecular PKR of chiral N-tethered 1,7-enynes 53 [64].
Scheme 29: Intramolecular PKR of chiral N-tethered 1,7-enyne bearing a vinyl fluoride [64].
Scheme 30: Catalytic intramolecular PKR of chiral N-tethered 1,7-enynes [64].
Scheme 31: Model fluorinated alkynes used by Riera and Fustero [70].
Scheme 32: PKR with norbornadiene and fluorinated alkynes 58 [71].
Scheme 33: Nucleophilic addition/detrifluoromethylation and retro Diels-Alder reactions [70].
Scheme 34: Tentative mechanism for the nucleophilic addition/retro-aldol reaction sequence.
Scheme 35: Catalytic PKR with norbornadiene [70].
Scheme 36: Scope of the PKR of trifluoromethylalkynes with norbornadiene [72].
Scheme 37: DBU-mediated detrifluoromethylation [72].
Scheme 38: A simple route to enone 67, a common intermediate in the total synthesis of α-cuparenone.
Scheme 39: Effect of the olefin partner in the regioselectivity of the PKR with trifluoromethyl alkynes [79].
Scheme 40: Intermolecular PKR of trifluoromethylalkynes with 2-norbornene reported by the group of Konno [54].
Scheme 41: Intermolecular PKR of diarylalkynes with 2-norbornene reported by the group of Helaja [80].
Scheme 42: Intermolecular PKR reported by León and Fernández [81].
Scheme 43: PKR reported with cyclopropene 73 [82].
Beilstein J. Org. Chem. 2020, 16, 1627–1635, doi:10.3762/bjoc.16.135
Graphical Abstract
Figure 1: (A) Synthetic routes to α-fluoroketones from silyl enol ethers or acetophenone derivatives. (B) Sel...
Scheme 1: Substrate scope with standard reaction conditions: alkyne (0.2 mmol), p-TolI (20 mol %), Selectfluor...
Figure 2: X-ray molecular structure of compound 2. Conformation of the carbonyl group and the fluoride with a...
Figure 3: (A) Structure activity relationship of the core scaffold. (B) Exploring the effect of methyl benzoa...
Figure 4: (A) Hammett plot varying the para-substitution on the alkyne (ρ ≈ 0). (B) Hammett plot varying the ...
Figure 5: An overview of the I(I)/I(III)-catalysed fluorohydration of alkynes.
Beilstein J. Org. Chem. 2020, 16, 1447–1455, doi:10.3762/bjoc.16.120
Graphical Abstract
Figure 1: Selected examples of triazinethione-containing bioactive compounds.
Scheme 1: Strategies for the synthesis of triazinethiones.
Scheme 2: Aldehyde substrate scope of three-component reaction of aldehydes, thiourea and trimethyl orthoform...
Scheme 3: Orthoformate substrate scope of the three component reaction of benzaldehyde, thiourea, and orthofo...
Scheme 4: Gram-scale synthesis of 6aa.
Figure 2: X-ray structure of 6-(methylthio)-4-phenyl-3,4-dihydro-1,3,5-triazine-2(1H)-thione (6aa) with therm...
Scheme 5: Control experiments for investigation of the mechanism.
Scheme 6: Plausible mechanism.
Beilstein J. Org. Chem. 2020, 16, 1313–1319, doi:10.3762/bjoc.16.112
Graphical Abstract
Figure 1: 3-Substituted isoxazolidin-4-ols resembling 3-hydroxypyrrolidines.
Scheme 1: Synthetic approach towards isoxazolidin-4-ols via the regioselective reductive cleavage of the C5–O...
Scheme 2: Hydroboration-oxidation of 4,5-unsubstituted 2,3-dihydroisoxazoles.
Figure 2: Selected NOE enhancements observed in the isoxazolidin-4-ol trans-8a. The arrows show the NOESY cor...
Scheme 3: Dess-Martin oxidation of isoxazolidin-4-ols to ketones.
Scheme 4: Inversion of the relative configuration of the isoxazolidine ring.
Figure 3: Selected NOE enhancements observed in the isoxazolidin-4-ol cis-10a. The arrows show the NOESY corr...
Scheme 5: N-debenzylation via N-Troc-protected isoxazolidines.
Beilstein J. Org. Chem. 2020, 16, 1203–1224, doi:10.3762/bjoc.16.105
Graphical Abstract
Figure 1: Structures of some current front-line anthelmintics discussed in this review. *Denotes the stereoge...
Figure 2: Structures of new anthelmintics drugs developed through repurposing, and new drugs or drug candidat...
Figure 3: Compounds with anthelmintic activity identified by a combination of screening against Ancylostoma c...
Figure 4: Inhibitors of S. mansoni thioredoxin glutathione reductase with anthelmintic activity [140].
Figure 5: Active compounds from anthelmintic screens using the MMV Pathogen Box. NTS: newly transformed schis...
Figure 6: Two resolution approaches to enantiopure PZQ (R)-5 discovered through A) open science and B) contra...
Beilstein J. Org. Chem. 2020, 16, 1075–1083, doi:10.3762/bjoc.16.94
Graphical Abstract
Figure 1: Biologically active selenides and diselenides having heteroaryl groups.
Figure 2: Ortep drawings of 2a (a and b) and 3a (c and d, thermal elipsoids indicate 50% probability).
Figure 3: The synthesis of bis(2-arylimidazopyridin-3-yl) diselenides. Reaction conditions: 1 (2 mmol), Se (2...
Figure 4: The synthesis of bis(2-arylimidazopyridin-3-yl) selenides. Reaction conditions: 1 (2 mmol), Se (1 m...
Scheme 1: Control reactions.
Scheme 2: Proposed mechanism (1).
Scheme 3: Proposed mechanism (2).
Figure 5: The cytotoxic effect of the bis(2-arylimidazo[1,2-a]pyridin-3-yl) diselenides 2 and selenides 3 on ...
Figure 6: The cytotoxic effect of the bis[2-(4-methoxyphenyl)imidazo[1,2-a]pyridin-3-yl] diselenide 2f on can...
Figure 7: Cytotoxic effect of the bis[2-(4-methoxyphenyl)imidazo[1,2-a]pyridin-3-yl] diselenide 2f on a cance...
Beilstein J. Org. Chem. 2020, 16, 966–973, doi:10.3762/bjoc.16.85
Graphical Abstract
Figure 1: (R)-MeO-MOP and our ligands.
Scheme 1: Asymmetric Suzuki–Miyaura coupling. Reaction conditions: 1 equiv N-aryl-bromoaryl compounds, 2 equi...
Scheme 2: Asymmetric Suzuki–Miyaura coupling. Reaction conditions: 1 equiv of bromoaryl compounds, 2 equiv of...
Scheme 3: Gram-scale reaction.
Scheme 4: Based on our analysis and speculation, a possible intermediate structure is proposed [65,66].
Scheme 5: Method A for the synthesis of amide substrates.
Scheme 6: Method B for the synthesis of amide substrates.