5° SEMINARIO QUÍMICA ORGÁNICA IQUIR 2023

SEMINARIO QUÍMICA ORGÁNICA 08-05-23

EXPOSITOR: Lic. Lina López

TÍTULO: "Rh(III)-Catalyzed Switchable [4 + 1] and [4 + 2] Annulation of N-aryl Pyrazolones with Maleimides: An Access to Spiro pyrazolo[1,2-a]indazole-pyrrolidine and Fused Pyrazolopyrrolo Cinnolines".

FUENTE: Chih-Yu Lin, Wan-Wen Huang, Ying-Ti Huang, Sandip Dhole, Indrajeet J. Barve and Chung-Ming Sun, J. Org. Chem. 2023, 88, 3424-3435.

DÍA, HORA y LUGAR: Lunes 8 de mayo de 2023, 14:00 h, Aula 18 y virtual

Modalidad virtual, Link: meet.google.com/hjn-ygro-twf (Plataforma MEET GOOGLE)

RESUMEN: 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 of N-aryl pyrazolone, followed by an intramolecular spirocyclization via aza-Michael type addition to afford spiro[pyrazolo[1,2-a]indazole-pyrrolidine]. However, prolonged reaction time converts in situ formed spiro[pyrazolo[1,2-a]indazole-pyrrolidine] into fused pyrazolopyrrolocinnoline. This unique product formation switch proceeds via strain-driven ring expansion through a 1,2-shift of the C-C bond.