for the carbocyclization/arylation of allenynes using arylboronic acids are reported. Arylated vinylallenes are obtained with the use of BF3⋅Et2O as an additive, whereas addition of water leads to arylated trienes. These conditions provide the respective products with excellent selectivities (generally >97:3) for a range of boronic acids and different allenynes. It has been revealed that water plays
In control: A highly selective carbocyclization/borylation of allenynes with bis(pinacolato)diboron (B2pin2) under palladium catalysis and with p‐benzoquinone (BQ) as the oxidant was developed. The use of either LiOAc⋅2 H2O with 1,2‐dichloroethane (DCE) as the solvent or BF3⋅Et2O together with THF is crucial for the selective formation of borylated trienes and vinylallenes, respectively.
对照:在钯催化下,以对苯醌 (BQ) 作为氧化剂,开发了双(频那醇)二硼 (B 2 pin 2 ) 的丙烯炔高度选择性碳环化/硼化反应。使用 LiOAc⋅2 H 2 O 和 1,2-二氯乙烷 (DCE) 作为溶剂或 BF 3 ⋅Et 2 O 和 THF 分别对于选择性形成硼基化三烯和乙烯基丙二烯至关重要。
Palladium‐Catalyzed Oxidative Carbocyclization–Carbonylation of Allenynes and Enallenes
作者:Chandra M. R. Volla、Javier Mazuela、Jan‐E. Bäckvall
DOI:10.1002/chem.201402688
日期:2014.6.16
A highly efficient oxidativecarbocyclization–carbonylation reaction cascade of allenynes and enallenes has been developed using a PdII salt in low catalytic amounts under ambient temperature and pressure (1 atm of carbon monoxide). The use of DMSO as an additive was found to be important for an efficient reaction. A wide range of alcohols as trapping reagents were used to give the corresponding esters