title: Phosphine-catalyzed [4+1] annulation of 1,3-(aza)dienes with maleimides: highly efficient construction of azaspiro[4.4]nonenes.
abstract: Phosphine-catalyzed [4+1] annulation of electron-deficient 1,3-dienes or 1,3-azadienes with maleimides has been successfully developed under very mild conditions, providing a convenient and highly efficient method for constructing 2-azaspiro[4.4]nonenes and 1,7-diazaspiro[4.4]nonenes. This reaction represents the first example of [4+1] cyclization between electron-deficient 4π-conjugated systems and non-allylic phosphorus ylides.
authors.affiliation: The State Key Laboratory of Elemento-Organic Chemistry and Department of Chemistry, Nankai University and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300071, P. R. China. zhengjiehe@nankai.edu.cn.
authors.forename: Mei
authors.initials: M
authors.lastname: Yang
authors.forename: Tianyi
authors.initials: T
authors.lastname: Wang
authors.forename: Shixuan
authors.initials: S
authors.lastname: Cao
authors.forename: Zhengjie
authors.initials: Z
authors.lastname: He
mesh_terms: D002384:Catalysis; D061565:Cycloaddition Reaction; D004583:Electrons; D008301:Maleimides / Q000737:chemistry*; D010720:Phosphines / Q000737:chemistry*; D013141:Spiro Compounds / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D008301:Maleimides; D010720:Phosphines; D013141:Spiro Compounds; C044646:phosphine