The title reaction was found to proceed in the presence of a rhodium/1,2-bis(diphenylphosphino)benzene catalyst. Variously substituted arylethenes and 1,3-dienes were obtained in good yields.
Highly Selective and Practical Alkyne-Alkyne Cross-Coupling Using Cp2ZrBu2 and Ethylene
作者:Zhenfeng Xi、Ryuichiro Hara、Tamotsu Takahashi
DOI:10.1021/jo00119a022
日期:1995.7
Highly selective alkyne-alkyne cross coupling reactions were achieved using Cp(2)ZrBu(2) and ethylene gas. First, alkynes were treated with 1.2 equiv of Cp(2)ZrBu(2) (Negishi reagent) under ethylene gas to give zirconacyclopentenes with high selectivities. Subsequent addition of a second alkyne to the solution of zirconacyclopentenes at 50 degrees C gave unsymmetrical zirconacyclopentadienes selectively. After hydrolysis unsymmetrical dienes were obtained in high yields.
Synthesis of 1,1,4,4-Tetrabromo-2-butenes and Related Compounds via Desilylation−Bromination of Silylated 1,3-Butadiene Derivatives
The combination of zirconocene-mediated coupling of silylated alkynes with a protonation−desilylation or bromination−desilylation process afforded otherwise unavailable butadiene derivatives. When (E,E)-2,3-dialkyl-1,4-bis(trimethylsilyl)-1,3-butadienes were treated with 3 equiv of Br2 in CH2Cl2, (E)-2,3-dialkyl-1,1,4,4-tetrabromo-2-butenes were obtained in excellent yields with perfect stereoselectivity
One-Pot Synthetic Routes to Multiply Substituted Indene Derivatives by Hydrolysis of Zirconocene-Mediated Intermolecular Coupling Reactions of Aromatic Ketones and Alkynes
Two one-pot multicomponent synthetic methods for highly substituted indenes are described. The intermolecularcoupling of aromatic ketones with alkynes on low-valent zirconocene species generates oxazirconacyclopentenes, which upon hydrolysis with 20% HCl for 3 h afforded indene derivatives in good to excellent yields. Similarly, the pair-selective coupling of two identical or different alkynes bearing