Rh(III)-Catalyzed Switchable [4 + 1] and [4 + 2] Annulation of <i>N</i>-Aryl Pyrazolones with Maleimides: An Access to Spiro Pyrazolo[1,2-<i>a</i>]indazole-pyrrolidine and Fused Pyrazolopyrrolo Cinnolines
作者:Chih-Yu Lin、Wan-Wen Huang、Ying-Ti Huang、Sandip Dhole、Indrajeet J. Barve、Chung-Ming Sun
DOI:10.1021/acs.joc.2c02338
日期:2023.3.17
A rhodium(III)-catalyzed controllable [4 + 1] and [4 + 2] annulation of N-aryl pyrazolones with maleimides as C1 and C2 synthon has been explored for the synthesis of spiro[pyrazolo[1,2-a]indazole-pyrrolidines] and fused pyrazolopyrrolo cinnolines. The product selectivity was achieved through time-dependent annulation. The [4 + 1] annulation reaction involves sequential Rh(III)-catalyzed C–H alkenylation
已探索了铑 (III) 催化的可控 [4 + 1] 和 [4 + 2] 环化N-芳基吡唑啉酮与马来酰亚胺作为 C1 和 C2 合成子,用于合成螺[吡唑并 [1,2- a ] 吲唑-pyrrolidines] 和稠合的 pyrazolopyrrolo cinnolines。产品选择性是通过时间依赖性环化实现的。[4 + 1] 环化反应包括顺序 Rh(III) 催化的N-芳基吡唑啉酮的 C-H 烯基化,然后通过氮杂-迈克尔型加成进行分子内螺环化,得到螺 [pyrazolo[1,2- a ]吲唑吡咯烷]。然而,延长的反应时间会原位转化形成的螺[吡唑并[1,2- a] indazole-pyrrolidine] 变成融合的 pyrazolpyrrolocinnoline。这种独特的产物形成转换通过 C-C 键的 1,2 位移通过应变驱动的环膨胀进行。