DOI: 10.1021/acs.orglett.6c04302 ISSN: 1523-7060
Solvent-Controlled Pd-Catalyzed Dearomative Reactions of Allenyl Benzoxazinones and 4-Nitroisoxazoles: Divergent Synthesis of Functionalized Quinolines and Fused Tetrahydroquinolines
Ran Wang, Jianren Dai, Zhaorui Lv, Xintong Yuan, Wei Qin, Ruixue Wang, Biming Mao, Chang Wang, Hongchao Guo, Chunhao YuanAbstract
We report an efficient solvent-modulated Pd-catalyzed dearomatization reaction between allenyl benzoxazinones and 4-nitroisoxazoles. When carried out in Diox, the transformation follows a cascade intramolecular cyclization/intermolecular dearomative Michael addition sequence, producing functionalized quinolines in up to 85% yield with >20:1 dr. In dichloromethane, the reaction proceeds through a dearomative formal [4 + 2] annulation instead, readily furnishing fused tetrahydroquinoline products with up to 83% yield and dr of >20:1. This work also constitutes the first report of dearomative reactivity derived from alkylidene−π-allylpalladium dipoles.