Synthesis of 3-arylated indolines from dearomatization of indoles

Oxidative N-Heterocyclic Carbene Catalyzed Dearomatization of Indoles to Spirocyclic Indolenines with a Quaternary Carbon Stereocenter

An efficient method for the asymmetric intramolecular dearomatization of indoles by using oxidative N-heterocyclic carbene catalysis is demonstrated. Valuable optically active spirocyclic indolenines bearing an all-carbon quaternary stereocenter are obtained in excellent yields and with excellent enantioselectivity. The starting indoles are readily prepared and the reactions proceed through an intramolecular indole 3-acylation with an in situ generated acyl azolium intermediate to form a spirocyclic ketone moiety.

Chiral Phosphoric Acid Catalyzed Intramolecular Dearomative Michael Addition of Indoles to Enones

An enantioselective intramolecular dearomative Michael addition of indolyl enones is presented. In the presence of catalytic amount of chiral phosphoric acid, various enantioenriched spiro-indolenines bearing a quaternary stereogenic center were obtained with good yields and enantioselectivity (up to 97% ee) under mild reaction conditions.

Revealing the electrophilicity of N-Ac indoles with FeCl3: a mechanistic study

The puzzling hydroarylation of N-Ac indoles promoted by iron trichloride involves a doubly activated intermediate: as supported by the electron density topology of a crystal, IR monitoring, and DFT calculations.

A formal intermolecular [4 + 2] cycloaddition reaction of 1,3-disubstituted indoles and alkylquinones

A formal [4 + 2] cycloaddition reaction of 1,3-disubstituted indoles and alkylquinones was realized to afford polycyclic indolines in good yields.

Photoassisted Synthesis of Complex Molecular Architectures: Dearomatization of Benzenoid Arenes with Aza-o-xylylenes via an Unprecedented [2+4] Reaction Topology

A new method was developed for the photoinduced dearomatization of arenes through an intramolecular cycloaddition with aza-o-xylylenes generated by excited-state intramolecular proton transfer (ESIPT) in the readily available photoprecursors. The [2+4] topology of this cycloaddition is unprecedented for photo-dearomatizations of benzenoid aromatic carbocycles. It provides rapid access to novel heterocycles, cyclohexadieno-oxazolidino-quinolinols, as valuable synthons for a broad range of post-photochemical transformations.

New opportunities in the stereoselective dearomatization of indoles

The regio- and stereoselective dearomatization of indoles is realized for the first time by combining readily available indolyl precursors and electron-rich allenes, namely allenamides and aryloxyallenes. Inter- as well as intramolecular condensations were realized under gold and Brønsted acid catalysis providing a range of densely functionalized indoline and indolenine cores in high yields and excellent stereochemical outcome. Chemodivergent reaction profiles (Micheal-type addition vs. [2+2]-cycloaddition) were realized by a tailored design of both reaction conditions and functionalization of the reaction partners.

Intermolecular dearomative C2-arylation of N-Ac indoles activated by FeCl3

We report the FeCl₃-mediated direct addition of electron-rich arenes to the C2-position of electrophilic N-Ac indoles under mild conditions (room temperature, air).

Iron-catalyzed domino indole fluorination/allenic aza-Claisen rearrangement

The synthesis of 2-allenyl-2-substituted-3,3-difluoroindolines has been accomplished, taking advantage of the reaction between N-allenyl-indoles and Selectfluor under iron catalysis.

Dearomatization of Indoles via Palladium-Catalyzed Allylic C-H Activation

The first Pd-catalyzed allylic dearomatization of substituted indoles triggered by C-H bond activation is reported. The presence of a catalytic amount of 2,5-DMBQ is proven to be a key factor for the high yield. This one-pot tandem allylic C-H activation/dearomatization sequence provides a straightforward access to 3,3-disubstituted indolines.