Iridium-Catalyzed Direct C–H Sulfamidation of Aryl Nitrones with Sulfonyl Azides at Room Temperature
作者:Chao Pi、Xiuling Cui、Yangjie Wu
DOI:10.1021/acs.joc.5b01377
日期:2015.8.7
Ir(III)-catalyzed direct C–H sulfamidation of aryl nitrones has been developed to synthesize various sulfamidated nitrones in moderate to excellent yields with excellent regioselectivity and broad functional group tolerance. This transformation could proceed smoothly at roomtemperature with low catalyst loading in the absence of external oxidants, acids, or bases. Molecular nitrogen was released as
chromatography (HPLC) and ESR spectrometry was used to isolate the radical products obtained by photolysis of o‐methylbenzaldehyde (1), o‐methylacetophenone (2) and o‐methylbenzophenone (3) in the presence of α‐phenyl‐N‐tert‐butylnitrone and its derivatives (4–19). Linear correlations between the hyperfine splitting constants and the Hammett parameters are observed. The mass spectra of the HPLC–ESR isolated
Enantioselective Synthesis of 4-Isoxazolines by 1,3-Dipolar Cycloadditions of Nitrones to Alkynals Catalyzed by Fluorodiphenylmethylpyrrolidines
作者:José Alemán、Alberto Fraile、Leyre Marzo、José Luis García Ruano、Cristina Izquierdo、Sergio Díaz-Tendero
DOI:10.1002/adsc.201200033
日期:2012.6.18
The first organocatalytic enantioselective 1,3‐dipolar reaction between nitrones and alkynalscatalyzed by (S)‐2‐(fluorodiphenylmethyl)pyrrolidine to give 4‐isoxazolines (2,3‐dihydroisoxazoles) with high enantiomeric excess, excellent yields and low catalyst loading (1–5 mol%) is presented. The catalytic loading could be reduced to 1 mol% with only slight increases in reaction times.
Addition of Silyl Ketene Acetals to Nitrones Catalyzed by Lanthanide Triflates
作者:Changtao Qian、Longcheng Wang
DOI:10.1016/s0040-4020(00)00636-0
日期:2000.9
α-Aryl-N-phenyl nitrones reacted with silyl ketene acetals mediated by lanthanum trifloromethanesulfonate (triflate) to afford the addition product in excellent yield under mild conditions. α-Aryl-N-tert-butyl nitrone reacted with ethyl trimethylsilylacetate to yield the unexpected α,β-unsaturated ester in a 100% E-form. A possible mechanism for the process is discussed.