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Regioselective and Stereoselective Pd-Catalyzed Intramolecular Arylation of Furans: Access to Spirooxindoles and 5<i>H</i>‑Furo[2,3‑<i>c</i>]quinolin-4-ones
Abstract
Herein, we report regio- and stereoselective intramolecular direct arylations of <i>N</i>-(2-bromophenyl)-2-furancarboxamides <b>1</b> to produce spirooxindoles <b>2</b> and 5<i>H</i>-furo[2,3-<i>c</i>]quinolin-4-ones <b>3</b> under different reaction conditions. Specifically, in the presence of Pd(PPh<sub>3</sub>)<sub>4</sub> as a catalyst, PPh<sub>3</sub> as a ligand, and K<sub>2</sub>CO<sub>3</sub> as a base, substrates <b>1</b> underwent intramolecular α-arylation, possibly via a Heck insertion pathway, to provide <b>2</b>, with the <i>Z</i>-isomer being favored. When the base was <i>t</i>-BuOLi and R<sup><b>1</b></sup> was an aryl group, the reaction favored <i>E</i>-<b>2</b>, possibly via an electrophilic palladation pathway. In contrast, in the presence of PdCl<sub>2</sub> as a catalyst, (<i>o</i>-OMePh)<sub>3</sub>P as a ligand, and PivOH as an additive, substrates <b>1</b> underwent intramolecular β-arylation to provide <b>3</b>, possibly via a concerted metalation–deprotonation process- Text
- Journal contribution
- Biophysics
- Biochemistry
- Computational Biology
- Biological Sciences not elsewhere classified
- electrophilic palladation pathway
- Stereoselective Pd-Catalyzed Intramolecular Arylation
- ligand
- intramolecular α- arylation
- Heck insertion pathway
- substrates 1
- K 2 CO 3
- presence
- catalyst
- quinolin -4-ones Herein
- intramolecular β- arylation