A direct method for the synthesis of polyfunctionalized unsaturated carbonyl derivatives by Michael addition of nitroalkanes to enediones with the help of DBU
作者:Roberto Ballini、Giovanna Bosica
DOI:10.1016/0040-4020(95)00136-v
日期:1995.4
The Michael addition of several nitroalkanes to dimethyl maleate, (Z)-3-hexene-2,5-dione, N-ethyl maleimide, and N-phenyl maleimide, in MeCN or THF, proceeds very efficiently on DBU as base, and furnishes good to high yields of polyfunctionalized unsaturated carbonyl derivatives.
A marking comprises a layer, preferably of film-forming material, which contains a photochromic compound. The photochromic compound is capable of changing colour when exposed to uv light, but can be converted to a permanently non-photochromic compound, preferably by over-exposure to uv light. An image is formed in the layer by converting the photochromic compound to a permanently non-photochromic compound in one or more selected areas. When the layer is subsequently viewed under uv light a colourless image of non-photochromic compound can be seen on a background of coloured photochromic compound.