title: Aryne [3 + 2] cycloaddition with N-sulfonylpyridinium imides and in situ generated N-sulfonylisoquinolinium imides: a potential route to pyrido[1,2-b]indazoles and indazolo[3,2-a]isoquinolines.
abstract: The aryne [3 + 2] cycloaddition process with pyridinium imides breaks the aromaticity of the pyridine ring. By equipping the imide nitrogen with a sulfonyl group, the intermediate readily eliminates a sulfinate anion to restore the aromaticity, leading to the formation of pyrido[1,2-b]indazoles. The scope and limitation of this reaction are discussed. As an extension of this chemistry, N-tosylisoquinolinium imides, generated in situ from N'-(2-alkynylbenzylidene)-tosylhydrazides via an AgOTf-catalyzed 6-endo-dig electrophilic cyclization, readily undergo aryne [3 + 2] cycloaddition to afford indazolo[3,2-a]-isoquinolines in the same pot, offering a highly efficient route to these potential anticancer agents.
authors.affiliation: Key Laboratory of Natural Medicine and Immuno-Engineering of Henan Province, Henan University, Jinming Campus, Kaifeng, Henan 475004, China PR.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Zhao
authors.forename: Pan
authors.initials: P
authors.lastname: Li
authors.forename: Chunrui
authors.initials: C
authors.lastname: Wu
authors.forename: Hongli
authors.initials: H
authors.lastname: Chen
authors.forename: Wenying
authors.initials: W
authors.lastname: Ai
authors.forename: Renhong
authors.initials: R
authors.lastname: Sun
authors.forename: Hailong
authors.initials: H
authors.lastname: Ren
authors.forename: Richard C
authors.initials: RC
authors.lastname: Larock
authors.forename: Feng
authors.initials: F
authors.lastname: Shi
mesh_terms: D003500:Cyclization; D007094:Imides / Q000737:chemistry*; D007191:Indazoles / Q000737:chemistry*; D007546:Isoquinolines / Q000737:chemistry*; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry; D010621:Phenazopyridine / Q000737:chemistry*; D013457:Sulfur Compounds / Q000737:chemistry*
chemical_list: D007094:Imides; D007191:Indazoles; D007546:Isoquinolines; D013457:Sulfur Compounds; D010621:Phenazopyridine; D009584:Nitrogen