Enantioselective Synthesis of Pyrrolidines by a Phosphine-Catalyzed γ-Umpolung/β-Umpolung Cascade.
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DOI: 10.1021/acs.orglett.2c00785
Abstract: Herein, we report an enantioselective catalytic annulation of electron-poor allenes with aminocrotonates. The reaction proceeds by the umpolung γ-amination of the allenoate and β-umpolung intramolecular conjugate addition. The reaction provides ready access to pyrrolidines using… read more here.
Keywords: umpolung umpolung; enantioselective synthesis; synthesis pyrrolidines; pyrrolidines phosphine ... See more keywords
Copper-Catalyzed Umpolung of N-2,2,2-Trifluoroethylisatin Ketimines for the Enantioselective 1,3-Dipolar Cycloaddition with Benzo[b]thiophene Sulfones.
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DOI: 10.1021/acs.orglett.2c01716
Abstract: A copper-catalyzed umpolung of N-2,2,2-trifluoroethylisatin ketimines for the enantioselective 1,3-dipolar cycloaddition with benzo[b]thiophene sulfones was developed. Using a catalyst system consisting of an (S,Sp)-tBu-Phosferrox ligand, Cu(OTf)2, and Cs2CO3, a range of pentacyclic spirooxindoles containing pyrrolidine… read more here.
Keywords: ketimines enantioselective; trifluoroethylisatin ketimines; catalyzed umpolung; umpolung trifluoroethylisatin ... See more keywords
N-Heterocyclic Carbene-Catalyzed Umpolung of Cyclopent-4-ene-1,3-diones for Activated Olefin-Isatin Cross-Coupling.
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DOI: 10.1021/acs.orglett.2c02413
Abstract: N-Heterocyclic carbene (NHC)-catalyzed umpolung of cyclopent-4-ene-1,3-diones that proceeds via the generation of nucleophilic deoxy-Breslow intermediates is presented. The carbene generated from a commercially available thiazolium salt catalyzed the cross-coupling between cyclopent-4-ene-1,3-diones and isatins to furnish… read more here.
Keywords: umpolung cyclopent; catalyzed umpolung; cyclopent ene; ene diones ... See more keywords
Pd-Catalyzed Umpolung of π–Allylpalladium Intermediates: Assembly of All-Carbon α-Vinyl Quaternary Aldehydes through C(sp3)–C(sp3) Coupling
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DOI: 10.1021/acscatal.8b03814
Abstract: Construction of sterically congested all-carbon quaternary centers represents a formidable challenge in synthetic chemistry. The method described herein provides direct and facile access to a series of structurally diverse and synthetically useful aliphatic aldehydes, bearing… read more here.
Keywords: vinyl quaternary; catalyzed umpolung; carbon; vinyl ... See more keywords
NHC-Catalyzed ε-Umpolung via p-Quinodimethanes and Its Nucleophilic Addition to Ketones
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DOI: 10.1021/acscatal.9b04409
Abstract: An unprecedented NHC-catalyzed generation of p-quinodimethanes via e-umpolung of 4-(chloromethyl)benzaldehydes and the following e-addition to active ketones was developed. A series of active keton... read more here.
Keywords: catalyzed umpolung; via quinodimethanes; addition; nhc catalyzed ... See more keywords