Synthesis of 1,4-Dicarbonyl Compounds from Silyl Enol Ethers and Bromocarbonyls, Catalyzed by an Organic Dye under Visible-Light Irradiation with Perfect Selectivity for the Halide Moiety over the Carbonyl Group
We report the visible-light-induced radical coupling reaction of silyl enol ethers with α-bromocarbonyl compounds to give 1,4-dicarbonyls. The reaction was effectively accelerated using an inexpensive organic dye (eosin Y) as a photoredox catalyst. 1,4-Dicarbonyl compounds alone were afforded, without the generation of carbonyl adducts of the α-halocarbonyls, which are usually generated in the presence
Catalytic Effect of Five-Coordinate Organotin Bromide or Tetraphenylstibonium Bromide on the Chemo- and Stereoselective Addition of Tin Enolate to<i>α</i>-Halo Ketone
tetraphenylstibonium bromide, similarly promoted the selective addition of tin enolates to the carbonyl moiety in α-halo ketones. The reaction with 2-chlorocyclohexanones and the enolates gave chlorohydrins bearing chloro- and hydroxyl groups in the cis-conformation. Chemoselective carbonyl addition to acyclic α-halo ketones was followed by effective cyclization to 2-(2-oxoethyl)oxiranes. The structural and bonding
Oxidative Generation of<i>α</i>-Radicals of Carbonyl Compounds from the<i>α</i>-Stannyl Derivatives and Their Reactions with Electron-Rich Olefins
作者:Yasushi Kohno、Koichi Narasaka
DOI:10.1246/bcsj.68.322
日期:1995.1
of the alkanoates by eliminating the stannylium ion. The thus-formed radicals react with various electron-rich olefinic compounds, such as silylenolethers, giving addition products in good yield. This method formally achieves selective cross couplingbetween alkanoates and ketones.
Phenyl alkyl ketones were photo-irradiated in the presence of Cr(VI) or Mn(VII) oxidants to yield 1,4-dicarbonyl compounds regiospecifically while 2-octanone gave a regioisomeric mixture of 2,5-, 2,6-, and 2,7-octadiones.
Synthesis of 1,4-diketones by fluoride-catalysed Michael addition and supported permanganate oxidation
作者:James H. Clark、David G. Cork
DOI:10.1039/c39820000635
日期:——
A wide variety of 1,4-diketones may be prepared from simple starting materials by using fluoride ion-catalysed Michaeladditions and silica gel-supported permanganate-promoted Nef transformations.