2 + 1] cycloaddition takes place in the rhodium-catalyzed reaction of 1,6-enynes with borylsilanes bearing an alkoxy group on the silicon atoms, which react as synthetic equivalents of silylene. The reaction proceeds efficiently in 1,2-dichloroethane at 80–110 °C in the presence of a rhodium catalyst bearing bis(diphenylphosphino)methane (DPPM) as a ligand to afford 1-silacyclopent-2-enes in good to
Palladium-Catalyzed Allylating Heteroannulation of <i>o-</i>Alkynyl-Allyloxybenzenes. A Route to 2-Substituted-3-Allylbenzo[b]furans
作者:Nuno Monteiro、Geneviève Balme
DOI:10.1055/s-1998-1755
日期:1998.7
In the presence of palladium(0), o-alkynyl allyloxybenzenes produce 2-substituted 3-allylbenzo[b]furans in fair yields. This heteroannulation is promoted by the η3-allyl palladium species issued from early reaction of the catalyst with the starting allyl aryl ether.
reactions of dibromoalkenes with arylboronic acids using a hydrazone–Cu catalyst system proceeded smoothly under mild conditions to afford the corresponding internal alkyne derivatives in good yields. Furthermore, we also succeeded in the synthesis of o-allyloxy(ethynyl)benzene derivatives, which are known to be effective precursors of various heterocyclic compounds, through this reaction.
Synthesis of
<i>o</i>
‐Allyloxy(ethynyl)benzene Derivatives by Cu‐Catalyzed Suzuki–Miyaura‐Type Reaction and Their Transformations into Heterocyclic Compounds
作者:Kohei Watanabe、Takashi Mino、Eri Ishikawa、Miyu Okano、Tatsuya Ikematsu、Yasushi Yoshida、Masami Sakamoto、Kazuki Sato、Kazuhiro Yoshida
DOI:10.1002/ejoc.201700217
日期:2017.4.26
Suzuki–Miyaura-type reactions of o-allyloxy(bromoethynyl)benzenes with arylboronic acids using a hydrazone/Cu catalyst system proceeded smoothly in iPrOH under mild conditions to afford the corresponding o-allyloxy(arylethynyl)benzenederivatives in good yields without decomposition of the allyloxy group. We have further demonstrated that annulation and enyne metathesis of the o-allyloxy(arylethynyl)benzene derivatives
“Diazo” not needed: The title reaction results in the rearrangement of oxonium ylides, which were prepared from readily available homopropargylic allylic ethers instead of diazo compounds, through two different mechanisms: a concerted 2,3‐sigmatropic rearrangement, or a stepwise 1,4‐allyl migration followed by a Claisen rearrangement (see scheme).