Iron(II)-Catalyzed Amidation of Aldehydes with Iminoiodinanes at Room Temperature and under Microwave-Assisted Conditions
摘要:
A method for the amidation of aldehydes with PhI=NTs/PhI=NNs as the nitrogen source and an inexpensive iron(II) chloride + pyridine as the in situ formed precatalyst under mild conditions at room temperature or microwave assisted conditions is described. The reaction was operationally straightforward and accomplished in moderate to excellent product yields (20-99%) and with complete chemoselectivity with the new C-N bond forming only at the formylic C-H bond in substrates containing other reactive functional groups. By utilizing microwave irradiation, comparable product yields and short reaction times of 1 h could be accomplished. The mechanism is suggested to involve insertion of a putative iron-nitrene/imido group to the formylic C H bond of the substrate via a H-atom abstraction/radical rebound pathway mediated by the precatalyst [Fe(py)(4)Cl-2] generated in situ from reaction of FeCl2 with pyridine.
Palladium-Catalyzed [4+2] Annulation of Aryl and Alkenyl Carboxamides with 1,3-Dienes via C–H Functionalization: Synthesis of 3,4-Dihydroisoquinolones and 5,6-Dihydropyridinones
作者:Manman Sun、Jinshan Li、Weida Chen、Haijian Wu、Jianguo Yang、Zhiming Wang
DOI:10.1055/s-0039-1690219
日期:2020.4
Palladium-catalyzed [4+2] annulation of aryl and alkenyl carboxamides with 1,3-dienes viaC–Hfunctionalization is developed using air as the terminal oxidant. The method demonstrates good functional group tolerance and high stereoselectivity, affording a series of 3,4-dihydroisoquinolones and 5,6-dihydropyridinones in yields of up to 99%. Palladium-catalyzed [4+2] annulation of aryl and alkenyl carboxamides
A synthetic protocol for the expedient construction of 5‐methylene‐1H‐pyrrol‐2(5H)‐one derivatives through rhodium‐catalyzed [4+1] annulation with gem‐difluoroacrylate as the C1 component was reported. By taking advantage of the twofold C−F bond cleavage occurring during the annulation, this reaction not only allows the synthesis of these heterocyclic compounds under overall oxidant‐free conditions