A C=O⋅⋅⋅Isothiouronium Interaction Dictates Enantiodiscrimination in Acylative Kinetic Resolutions of Tertiary Heterocyclic Alcohols

A combination of experimental and computational studies have identified a C=O⋅⋅⋅isothiouronium interaction as key to efficient enantiodiscrimination in the kinetic resolution of tertiary heterocyclic alcohols bearing up to three potential recognition motifs at the stereogenic tertiary carbinol center. This discrimination was exploited in the isothiourea-catalyzed acylative kinetic resolution of tertiary heterocyclic alcohols (38 examples, s factors up to &gt;200). The reaction proceeds at low catalyst loadings (generally 1 mol %) with either isobutyric or acetic anhydride as the acylating agent under mild conditions.</p

Stereospecific Asymmetric N-Heterocyclic Carbene (NHC)-Catalyzed Redox Synthesis of Trifluoromethyl Dihydropyranones and Mechanistic Insights

N-Heterocyclic carbene (NHC)-catalyzed redox asymmetric hetero-Diels–Alder reactions of α-aroyloxyaldehydes with β-trifluoromethyl enones generates synthetically useful dihydropyranones containing a stereogenic trifluoromethyl substituent in good yields (up to 81%) and excellent diastereoselectivity and enantioselectivity (up to >95:5 dr and >99% ee). The process is stereospecific, with use of either (E)- or (Z)-β-trifluoromethyl enones forming syn- or anti-dihydropyranone products, respectively. Mechanistic studies through in situ kinetic analysis of the reaction reveal key differences in reactivity between chiral NHC precursor 1 and an achiral NHC precursor

A C=O⋅⋅⋅Isothiouronium Interaction Dictates Enantiodiscrimination in Acylative Kinetic Resolutions of Tertiary Heterocyclic Alcohols

© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim A combination of experimental and computational studies have identified a C=O⋅⋅⋅isothiouronium interaction as key to efficient enantiodiscrimination in the kinetic resolution of tertiary heterocyclic alcohols bearing up to three potential recognition motifs at the stereogenic tertiary carbinol center. This discrimination was exploited in the isothiourea-catalyzed acylative kinetic resolution of tertiary heterocyclic alcohols (38 examples, s factors up to \u3e200). The reaction proceeds at low catalyst loadings (generally 1 mol %) with either isobutyric or acetic anhydride as the acylating agent under mild conditions

Stereospecific Asymmetric N‑Heterocyclic Carbene (NHC)-Catalyzed Redox Synthesis of Trifluoromethyl Dihydropyranones and Mechanistic Insights

N-Heterocyclic carbene (NHC)-catalyzed redox asymmetric hetero-Diels–Alder reactions of α-aroyloxyaldehydes with β-trifluoromethyl enones generates synthetically useful dihydropyranones containing a stereogenic trifluoromethyl substituent in good yields (up to 81%) and excellent diastereoselectivity and enantioselectivity (up to >95:5 dr and >99% ee). The process is stereospecific, with use of either (<i>E</i>)- or (<i>Z</i>)-β-trifluoromethyl enones forming <i>syn</i>- or <i>anti</i>-dihydropyranone products, respectively. Mechanistic studies through in situ kinetic analysis of the reaction reveal key differences in reactivity between chiral NHC precursor <b>1</b> and an achiral NHC precursor

Stereospecific Asymmetric N‑Heterocyclic Carbene (NHC)-Catalyzed Redox Synthesis of Trifluoromethyl Dihydropyranones and Mechanistic Insights

N-Heterocyclic carbene (NHC)-catalyzed redox asymmetric hetero-Diels–Alder reactions of α-aroyloxyaldehydes with β-trifluoromethyl enones generates synthetically useful dihydropyranones containing a stereogenic trifluoromethyl substituent in good yields (up to 81%) and excellent diastereoselectivity and enantioselectivity (up to >95:5 dr and >99% ee). The process is stereospecific, with use of either (<i>E</i>)- or (<i>Z</i>)-β-trifluoromethyl enones forming <i>syn</i>- or <i>anti</i>-dihydropyranone products, respectively. Mechanistic studies through in situ kinetic analysis of the reaction reveal key differences in reactivity between chiral NHC precursor <b>1</b> and an achiral NHC precursor

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