Two Catalytic Annulation Modes via Cu-Allenylidenes with Sulfur Ylides that Are Dominated by the Presence or Absence of Trifluoromethyl Substituents

• Published in: iScience Vol. 23; no. 4; p. 100994
• Main Authors: Gannarapu, Malla Reddy, Zhou, Jun, Jiang, Bingyao, Shibata, Norio
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 24.04.2020; Elsevier
• Subjects: Organic Chemistry; Organic Synthesis; Physical Organic Chemistry; Physical Organic Chemistry; Organic Synthesis; Organic Chemistry
• ISSN: 2589-0042; 2589-0042
• DOI: 10.1016/j.isci.2020.100994

We disclose the Cu-catalyzed enantioselective synthesis of 3-methyl-3-propargyl-indolines, which contain a quaternary stereogenic carbon center, via the decarboxylative [4 + 1] annulation of 4-methyl-4-propargyl-benzoxazinanones with variety of sulfur ylides. The reaction proceeds predominantly through a γ-attack at the Cu-allenylidene intermediates by sulfur ylides to provide the corresponding indolines in good yield and high enantioselectivity (up to 91% ee). In contrast, the reaction of 4-trifluoromethyl-4-propargyl-benzoxazinanones with sulfur ylides delivers 3-trifluoromethyl-2-functionalized indoles in good to high yield via an unexpected α-attack at the Cu-allenylidene intermediates. Control over the α/γ-attack at the Cu-allenylidene intermediates by the same interceptors was achieved for the first time by the use of trifluoromethyl substituents. [Display omitted] •Fluorine changes the catalytic decarboxylative annulation modes•All carbon quarternary stereocentered indolines, up to 91% ee•An unexpected α-attack at the Cu-allenylidene intermediate with CF3•3-CF3-substituted indoles with a 2-functional group Organic Chemistry; Organic Synthesis; Physical Organic Chemistry