title: Ring-Contraction Disproportionation/Spirocyclization Cascade Reaction of Isochromeno[4,3-b]indol-5(11H)-ones: Synthesis of N-Unsubstituted Spirocycles.
abstract: An efficient ring-contraction reaction of isochromeno[4,3-b]indol-5(11H)-ones via a nucleophile-induced disproportionation/spirocyclization cascade process has been developed under mild conditions. The process realized the conversion of isochromeno[4,3-b]indol-5(11H)-ones into N-unsubstituted spiro[indoline-2,1'-isobenzofuran]-3,3'-diones and spiro[indoline-2,1'-isoindoline]-3,3'-diones in the absence of a transition-metal catalyst or oxidant. Gram-scale reaction further demonstrated the practicability of the protocol.
authors.affiliation: Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University , Tianjin 300072, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University , Tianjin 300072, China.
authors.forename: Guangshuai
authors.initials: G
authors.lastname: Zhou
authors.affiliation: Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University , Tianjin 300072, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University , Tianjin 300072, China.
authors.forename: Daisy
authors.initials: D
authors.lastname: Zhang-Negrerie
authors.affiliation: Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University , Tianjin 300072, China.|Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) , Tianjin 300072, China.
authors.forename: Yunfei
authors.initials: Y
authors.lastname: Du
authors.affiliation: Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University , Tianjin 300072, China.
authors.forename: Kang
authors.initials: K
authors.lastname: Zhao