New advances in asymmetric organocatalysis
Asymmetric organocatalysis became one of the principal methods for the catalytic synthesis of chiral compounds. This thematic issue in the Beilstein Journal of Organic Chemistry aims to highlight new developments across all subdisciplines of enantioselective organocatalysis. This timely collection of articles deals with methodological advances in both covalent (enamine, iminium, phosphine, carbene, etc.) and noncovalent organocatalytic activations, which are often connected to developments of new catalysts. Important mechanistic and computational studies deepen our understanding of this topic and the underlying processes. The gradual maturation of this field is demonstrated by applications of its methodologies to target molecules synthesis, such as natural products or compounds of medicinal interest.
- Letter
- Published 08 Apr 2021
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Scheme 1: Overview about established methods to access enantioenriched 2 and the herein investigated kinetic ...
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Scheme 2: Use of alternative acylating agents 4 for the kinetic resolution of rac-2.
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- Full Research Paper
- Published 14 Jun 2021
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Scheme 1: Reactions of α-nitroketones with unsaturated pyrazolone and with 4-benzylidenepyrrolidine-2,3-dione....
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Scheme 2: Reaction of 4-benzylidenedihydrofuran-2,3-dione (4) with α-nitroketones 2b,c. Reaction conditions: ...
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- Full Research Paper
- Published 21 Jul 2021
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Scheme 1: Mechanism for the phosphine-initiated oxa-Michael addition.
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Figure 1: Above: Michael acceptors, Michael donors and catalysts used in this study; pKa (respectively pKa of...
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Figure 2: Left: double-bond conversion of the polymerization of 4 initiated by 5 mol % TPP, MMTPP or TMTPP af...
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Figure 3: Left: Oxidation stability of the phosphines. Phosphine oxide content in % as determined by 31P NMR ...
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- Review
- Published 03 Aug 2021
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Figure 1: Coumarin-derived commercially available drugs.
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Figure 2: Inhibition of acetylcholinesterase by coumarin derivatives.
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Scheme 1: Michael addition of 4-hydroxycoumarins 1 to α,β‐unsaturated enones 2.
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Scheme 2: Organocatalytic conjugate addition of 4-hydroxycoumarin 1 to α,β-unsaturated aldehydes 2 followed b...
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Scheme 3: Synthesis of 3,4-dihydrocoumarin derivatives 10 through decarboxylative and dearomatizative cascade...
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Scheme 4: Total synthesis of (+)-smyrindiol (17).
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Scheme 5: Michael addition of 4-hydroxycoumarin (1) to enones 2 through a bifunctional modified binaphthyl or...
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Scheme 6: Michael addition of ketones 20 to 3-aroylcoumarins 19 using a cinchona alkaloid-derived primary ami...
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Scheme 7: Enantioselective reaction of cyclopent-2-enone-derived MBH alcohols 24 with 4-hydroxycoumarins 1.
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Scheme 8: Sequential Michael addition/hydroalkoxylation one-pot approach to annulated coumarins 28 and 30.
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Scheme 9: Michael addition of 4-hydroxycoumarins 1 to enones 2 using a binaphthyl diamine catalyst 31.
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Scheme 10: Asymmetric Michael addition of 4-hydroxycoumarin 1 with α,β-unsaturated ketones 2 catalyzed by a ch...
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Scheme 11: Catalytic asymmetric β-C–H functionalization of ketones via enamine oxidation.
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Scheme 12: Enantioselective synthesis of polycyclic coumarin derivatives 37 catalyzed by an primary amine-imin...
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Scheme 13: Allylic alkylation reaction between 3-cyano-4-methylcoumarins 39 and MBH carbonates 40.
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Scheme 14: Enantioselective synthesis of cyclopropa[c]coumarins 45.
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Scheme 15: NHC-catalyzed lactonization of 2-bromoenals 46 with 4-hydroxycoumarin (1).
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Scheme 16: NHC-catalyzed enantioselective synthesis of dihydrocoumarins 51.
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Scheme 17: Domino reaction of enals 2 with hydroxylated malonate 53 catalyzed by NHC 55.
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Scheme 18: Oxidative [4 + 2] cycloaddition of enals 57 to coumarins 56 catalyzed by NHC 59.
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Scheme 19: Asymmetric [3 + 2] cycloaddition of coumarins 43 to azomethine ylides 60 organocatalyzed by quinidi...
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Scheme 20: Synthesis of α-benzylaminocoumarins 64 through Mannich reaction between 4-hydroxycoumarins (1) and ...
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Scheme 21: Asymmetric addition of malonic acid half-thioesters 67 to coumarins 66 using the sulphonamide organ...
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Scheme 22: Enantioselective 1,4-addition of azadienes 71 to 3-homoacyl coumarins 70.
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Scheme 23: Michael addition/intramolecular cyclization of 3-acylcoumarins 43 to 3-halooxindoles 74.
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Scheme 24: Enantioselective synthesis of 3,4-dihydrocoumarins 78 catalyzed by squaramide 73.
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Scheme 25: Organocatalyzed [4 + 2] cycloaddition between 2,4-dienals 79 and 3-coumarincarboxylates 43.
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Scheme 26: Enantioselective one-pot Michael addition/intramolecular cyclization for the synthesis of spiro[dih...
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Scheme 27: Michael/hemiketalization addition enantioselective of hydroxycoumarins (1) to: (a) enones 2 and (b)...
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Scheme 28: Synthesis of 2,3-dihydrofurocoumarins 89 through Michael addition of 4-hydroxycoumarins 1 to β-nitr...
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Scheme 29: Synthesis of pyrano[3,2-c]chromene derivatives 93 via domino reaction between 4-hydroxycoumarins (1...
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Scheme 30: Conjugated addition of 4-hydroxycoumarins 1 to nitroolefins 95.
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Scheme 31: Michael addition of 4-hydroxycoumarin 1 to α,β-unsaturated ketones 2 promoted by primary amine thio...
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Scheme 32: Enantioselective synthesis of functionalized pyranocoumarins 99.
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Scheme 33: 3-Homoacylcoumarin 70 as 1,3-dipole for enantioselective concerted [3 + 2] cycloaddition.
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Scheme 34: Synthesis of warfarin derivatives 107 through addition of 4-hydroxycoumarins 1 to β,γ-unsaturated α...
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Scheme 35: Asymmetric multicatalytic reaction sequence of 2-hydroxycinnamaldehydes 109 with 4-hydroxycoumarins ...
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Scheme 36: Mannich asymmetric addition of cyanocoumarins 39 to isatin imines 112 catalyzed by the amide-phosph...
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Scheme 37: Enantioselective total synthesis of (+)-scuteflorin A (119).
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- Letter
- Published 17 Aug 2021
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Figure 1: Strategy for the synthesis of glutamate and pyroglutamate derivatives and several natural products ...
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Figure 2: Effect of the aryl substituent on reaction efficiency and selectivity.
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Figure 3: Proposed transition state model.
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- Review
- Published 01 Sep 2021
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Figure 1: a) Binding interactions in the chloride channel of E. coli. and b) examples of chloride, cyanide, n...
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Figure 2: a) H-bond vs anion-binding catalysis and b) activation modes in anion-binding catalysis.
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Scheme 1: First proposed anion-binding mechanism in the thiourea-catalyzed acetalization of benzaldehyde.
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Scheme 2: a) Thiourea-catalyzed enantioselective acyl-Pictet–Spengler reaction of tryptamine-derived imines 4...
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Scheme 3: Proposed mechanism of the thiourea-catalyzed enantioselective Pictet–Spengler reaction of hydroxyla...
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Scheme 4: a) Thiourea-catalyzed intramolecular Pictet–Spengler-type cyclization of hydroxylactam-derived N-ac...
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Scheme 5: Enantioselective Reissert-type reactions of a) (iso)quinolines with silyl ketene acetals, and b) vi...
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Figure 3: Role of the counter-anion: a) Anion acting as a spectator and b) anion participating directly as th...
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Scheme 6: Enantioselective selenocyclization catalyzed by squaramide 28.
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Scheme 7: Desymmetrization of meso-aziridines catalyzed by bifunctional thiourea catalyst 31.
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Scheme 8: Anion-binding-catalyzed desymmetrization of a) meso-aziridines catalyzed by chiral triazolium catal...
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Scheme 9: Bis-urea-catalyzed enantioselective fluorination of a) β-bromosulfides and b) β-haloamines by Gouve...
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Scheme 10: a) Bifunctional thiourea anion-binding – basic/nucleophilic catalysts. Selected applications in b) ...
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Scheme 11: Thiourea-catalyzed enantioselective polycyclization reaction of hydroxylactams 51 through cation–π ...
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Scheme 12: Enantioselective aza-Sakurai cyclization of hydroxylactams 56 implicating additional cation–π and L...
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Scheme 13: Enantioselective tail-to-head cyclization of neryl chloride derivatives.
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Scheme 14: Cation–π interactions in anion binding-catalyzed asymmetric addition reactions: a) addition of indo...
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Scheme 15: Bisthiourea catalyzed oxa-Pictet–Spengler reaction of indole-based alcohols and aromatic aldehydes ...
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Scheme 16: Anion-binding catalyst development in the enantioselective addition of silyl ketene acetals to 1-ch...
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Scheme 17: a) Macrocyclic bis-thiourea catalyst in a diastereoselective glycosylation reaction. b) Competing SN...
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Scheme 18: a) Folding mechanism of oligotriazoles upon anion recognition. b) Representative tetratriazole 82 c...
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Scheme 19: Switchable chiral tetratriazole catalyst 86 in the enantioselective addition of silyl ketene acetal...
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- Letter
- Published 02 Sep 2021
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Figure 1: The importance of the 3,3-spirooxindole core and its access through enantioselective enolate alkyla...
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Scheme 1: A) SN2 alkylation of 3-subtituted-2-oxindoles not readily functionalisable; B) Previous work: enant...
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Figure 2: Substrate scope. aIsolated yield. bDetermined by CSP-HPLC. cValue in brackets refers to reaction co...
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Scheme 2: Enantioselective synthesis of a CRTH2 receptor antagonist.
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- Published 16 Sep 2021
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Figure 1: Synthetic strategies employing chiral Brønsted acid catalysis.
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Scheme 1: The substrate scope of the aminalization reaction for different aldehydes. aAfter recrystallization...
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Scheme 2: The substrate scope of the intermolecular aminalization reaction for anthranilamide derivatives. aA...
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Figure 2: X-ray single-crystal structure of aminal 3l with the displacement ellipsoids drawn at the 30% proba...
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- Review
- Published 18 Oct 2021
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Scheme 1: Asymmetric aza-Michael addition catalyzed by cinchona alkaloid derivatives.
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Scheme 2: Intramolecular 6-exo-trig aza-Michael addition reaction.
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Scheme 3: Asymmetric aza-Michael/Michael addition cascade reaction of 2-nitrobenzofurans and 2-nitrobenzothio...
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Scheme 4: Asymmetric aza-Michael addition of para-dienone imide to benzylamine.
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Scheme 5: Asymmetric synthesis of chiral N-functionalized heteroarenes.
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- Full Research Paper
- Published 25 Oct 2021
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Figure 1: Catalyst design principles.
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Scheme 1: Synthesis of isothiocyanate 3a and isocyanate 3b.
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Scheme 2: Synthesis of sulfinylthioureas C1 and ureas C2.
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Scheme 3: Synthesis of adducts 8a,d,f in solution.
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Figure 2: DFT-calculated (PBEh-3c/def2-SV(P)//M06-2X/def2-TZVP) structures of catalyst (S,R) and (S,S)-C2, en...
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Figure 3: a) Arrangements of reactants in the transition states; b) DFT-calculated (PBEh-3c/def2-SV(P)//M06-2...
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Figure 4: DFT-calculated (PBEh-3c/def2-SV(P)//M06-2X/def2-TZVP) reaction profile for the Michael addition of ...
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- Published 27 Oct 2021
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Scheme 1: Selected methods for the synthesis of enantioenriched β-silyl nitroalkanes, synthesis of chiral org...
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Scheme 2: Scope of substrates. Reaction conditions: 1 (0.2 mmol), 2 (0.5 mmol), catalyst VII (0.01 mmol, 5 mo...
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Scheme 3: Synthesis of ent-3. Reaction conditions: 1 (0.2 mmol), 2 (0.5 mmol), catalyst VIII (0.01 mmol, 5 mo...
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Scheme 4: Organocatalytic 1,4-conjuagte addition of nitromethane (2) to enone 3o.
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Figure 1: Single crystal X-ray structure of ent-3k (CCDC 2097263).
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Scheme 5: Preparative scale synthesis of 3c and ent-3d.
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- Published 04 Jan 2022
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Figure 1: Selected examples of natural products and drugs possessing the indane scaffold.
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Scheme 1: Known strategies and conceptual advance of this contribution.
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Figure 2: Selected examples of bioactive spirobarbiturates.
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Figure 3: The screened organocatalysts.
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Scheme 2: Substrate scope of 2-isothiocyanato-1-indanones. The reactions were carried out with 1 (0.12 mmol), ...
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Scheme 3: Substrate scope of barbiturate-based olefins. The reactions were carried out with 1a (0.12 mmol), 2...
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Figure 4: X-ray crystal structure of 3ae (displacement ellipsoids are drawn at the 50% probability level).
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Scheme 4: Gram-scale synthesis of 3ah.
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Scheme 5: Further transformation of 3ah.
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Scheme 6: One-pot three-component reaction.
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Scheme 7: Proposed reaction mechanism.
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