title: Regioselective and Stereoselective Pd-Catalyzed Intramolecular Arylation of Furans: Access to Spirooxindoles and 5H-Furo[2,3-c]quinolin-4-ones.
abstract: Herein, we report regio- and stereoselective intramolecular direct arylations of N-(2-bromophenyl)-2-furancarboxamides 1 to produce spirooxindoles 2 and 5H-furo[2,3-c]quinolin-4-ones 3 under different reaction conditions. Specifically, in the presence of Pd(PPh3)4as a catalyst, PPh3as a ligand, and K2CO3as a base, substrates 1 underwent intramolecular α-arylation, possibly via a Heck insertion pathway, to provide 2, with the Z-isomer being favored. When the base was t-BuOLi and R1was an aryl group, the reaction favored E-2, possibly via an electrophilic palladation pathway. In contrast, in the presence of PdCl2as a catalyst, (o-OMePh)3P as a ligand, and PivOH as an additive, substrates 1 underwent intramolecular β-arylation to provide 3, possibly via a concerted metalation-deprotonation process.
authors.affiliation: Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology , Guangzhou 510640, PR China.
authors.forename: Jianchao
authors.initials: J
authors.lastname: Liu
authors.affiliation: Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology , Guangzhou 510640, PR China.
authors.forename: Hui
authors.initials: H
authors.lastname: Peng
authors.affiliation: Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology , Guangzhou 510640, PR China.
authors.forename: Yongjie
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology , Guangzhou 510640, PR China.
authors.forename: Huanfeng
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology , Guangzhou 510640, PR China.
authors.forename: Biaolin
authors.initials: B
authors.lastname: Yin