MeOTf-Mediated Alkynylation of Selenoamides Leading to β-Methylselenenyl α,β-Unsaturated Ketones and Their Characterization
作者:Toshiaki Murai、Yuichiro Mutoh、Shinzi Kato
DOI:10.1021/ol015968u
日期:2001.6.1
[reaction: see text] beta-Methylselenenyl alpha,beta-unsaturatedketones were effectively synthesized by treating selenoamides with methyl triflate, followed by reaction with lithium acetylides. The reaction proceeded with high stereoselectivity to give exclusively Z-isomers. (77)Se NMR studies and X-ray molecular structure analysis of beta-methylselenenyl alpha,beta-unsaturatedketones suggested that
Reactions of Phosphonate Carbanions with Selenium or Sulfur in the Presence of Amines. Synthesis of Seleno- and Thioamides.
作者:Kentaro Okuma、Koumei Ikari、Hiroshi Ohta
DOI:10.1246/cl.1992.131
日期:——
The reaction of phosphonatecarbanions with elemental selenium in the presence of amines afforded the corresponding selenoamides in moderate yields. The reaction of these anions with sulfur also gave thioamides. These reactions might proceed through thio- or selenoaldehyde intermediates
The reaction of selenoamides with organolithiumreagents proceeds in a carbophilic manner, and more interestingly, the presence of excess lithium reagents causes a novel deselenation reaction from the carbophilic adducts.
We investigated the scavenging effects of tertiary selenoamide compounds for super oxide radicals using a highly sensitive and quantitative chemiluminescence method. At 333 nM, tertiary selenoamide compounds scavenged 25.8-81.6% of O-2(-.).N-(Phenylselenocarbonyl) piperidine was the most effective scavenger of superoxide radicals. While N,N-diethyl-2-selenonaphthylamide and N,N-diethyl-4-chloroselenobenzamide was a moderately effective scavenger of superoxide radicals. The IC50 of N-(phenylselenocarbonyl) piperidine and N,N-diethyl-2-selenonaphthylamide were determined to be 110 and 182 nM, respectively. The results suggest that tertiary selenoamide compounds are useful scavengers of superoxide radicals. (C) 2004 Elsevier B.V. All rights reserved.