The inherently strained furan-fused cyclobutenes, in situ generated via cycloisomerizations of allenyl ketones bearing cyclopropyl moiety under gold catalysis, have been utilized as reactive building blocks toward cross cycloadditions. The [4 + 2] and [3 + 2] annulations of these species with benzo[c]isoxazoles and N-iminoquinazolinium ylides furnish various three-dimensional cyclobutane-bridged polyheterocycles
通过在金催化下通过带有环丙基部分的烯丙基酮的环异构化原位产生的固有应变的呋喃稠合的环丁烯已被用作朝向交叉环加成的反应性结构单元。这些物质与苯并[ c ]异恶唑和N-亚氨基喹唑啉鎓叶立德的[4 + 2]和[3 + 2]环以良好的收率提供各种三维环丁烷桥联的多杂环化合物。多种典型的电子不足的1,3-二烯,杂二烯和1,3-偶极子可以捕获呋喃稠合的环丁烯,从而提供多种多环结构。
Cu(I)-Catalyzed Domino Reaction of 3-Cyclopropylideneprop-2-en-1-ones
CuCl-catalyzed cyclization–dimerization reactions of 3-cyclopropylideneprop-2-en-1-ones provide an interesting route to benzofuran-7(3aH)-one derivatives with one highly strained three-membered ring and one four-membered ring via intramolecular cycloisomerization, sequential bimolecular [4 + 2] cycloaddition, opening of the oxa-bridge, and ring contraction. Furthermore, the reaction was monitored by NMR experiments
A novel PdCl2-catalyzed oxidative cycloisomerization of 3-cyclopropylideneprop-2-en-1-ones, providing a facile synthesis of highly strained functionalized 2-alkylidenecyclobutanones via furan-fused cyclobutene intermediates, is reported. An interesting route to 2(3H)-furanones with a spiro-cyclopropane unit from the obtained 2-alkylidenecyclobutanones via a ring-contraction rearrangement reaction is
Herein, we describe a gold(I)-catalyzed generation of nonclassical gold-containing 1,4-all-carbon dipoles from cycloisomerization/1,2-carbene transfer/ring opening cascade reactions of readily accessible allenyl ketones bearing a cyclopropyl moiety and its cyclization with tropone. This method features an unprecedented formal [8+4] high-order cycloaddition under mild conditions for delivering structurally
cyclobutenes via Cu(I)-catalyzedcycloisomerization of readily available allenyl ketones bearing a cyclopropyl moiety are a highly reactive and powerful species, which undergo annulative fragmentation with terminal ynones to afford a wide variety of functional furans in moderate to high yields. This ring-distortion protocol features an unprecedented strain-controlled cycloisomerization/Diels–Alder/retro-Diels–Alder