Synthesis of Trifluoroethyl Pyrazolines via Trichloroisocyanuric Acid Promoted Cascade Cyclization/Trifluoromethylation of β,γ-Unsaturated Hydrazones
作者:Bingbing Chang、Yingpeng Su、Danfeng Huang、Ke-Hu Wang、Weigang Zhang、Ya Shi、Xinghu Zhang、Yulai Hu
DOI:10.1021/acs.joc.8b00009
日期:2018.4.20
A novel and efficient protocol for the construction of trifluoroethyl pyrazolines has been developed by cascade cyclization/trifluoromethylation reaction of β,γ-unsaturatedhydrazones. This strategy uses cheap and commercially available trichloroisocyanuric acid as promoter and TMSCF3 as the trifluoromethylating reagent, which make the trifluoromethylating process much cheaper. A wide range of substrates
An efficienthalocyclization of β,γ-unsaturatedhydrazones with N-bromosuccinimide was developed without the addition of any additives under mild reaction conditions to provide facile access to biologically important 4,5-dihydropyrazoles. Under the optimized conditions, a variety of highly substituted 4,5-dihydropyrazole derivatives were obtained in generally good yields. Moreover, this reaction can
Cooperativity within the catalyst: alkoxyamide as a catalyst for bromocyclization and bromination of (hetero)aromatics
作者:Haripriyo Mondal、Md Raja Sk、Modhu Sudan Maji
DOI:10.1039/d0cc04673f
日期:——
Alkoxyamide has been reported as a catalyst for the activation of N-bromosuccinimide to perform bromocyclization and bromination of a wide range of substrates in a lipophilic solvent, where adequate suppression of the background reactions was observed. The key feature of the active site is the alkoxy group attached to the sulfonamide moiety, which facilitates the acceptance as well as the delivery
An asymmetric synthesis of 5-halomethyl pyrazolines and isoxazolines which bear a tertiary stereocenter by catalytic halocyclization of β,γ-unsaturatedhydrazones and ketoximes is described. By using Brønsted acids of anionic chiral Co(III) complexes as catalysts, a variety of chiral 5-halomethyl pyrazolines and isoxazolines were obtained in good yields with high enantioselectivities (up to 99% yield