The nitrovinyl-substituted quinones 2-(2-nitrovinyl)-1,4-benzoquinone and 2-(2-nitrovinyl)-1,4-naphthoquinone react with a variety of cyclic and acyclic enol ethers via two competing pathways. In one pathway, the nitrovinylquinone acts as an inverse electron-demand [4 + 2] diene. This gives quinoid carbocycles, which readily tautomerize to their hydroquinone form. The other pathway involves conjugate
硝基乙烯基取代的醌2-(2-
硝基乙烯基)-1,4-苯醌和2-(2-
硝基乙烯基)-
1,4-萘醌通过两种竞争途径与各种环状和无环烯醇醚反应。在一个途径中,
硝基乙烯基醌起反电子需求[4 + 2]二烯的作用。这产生了醌型碳环,其容易互变异构化为其
氢醌形式。另一途径涉及将烯醇醚以共轭(迈克尔)加成至
硝基乙烯基醌,然后闭环。得到二氢
苯并呋喃,其可以消除醇而得到
苯并呋喃。受阻的烯醇醚倾向于促进共轭加成途径,而受阻较少的烯醇醚则倾向于环加成。