Copper-catalyzed synthesis of allenylboronic acids. Access to sterically encumbered homopropargylic alcohols and amines by propargylboration
作者:Jian Zhao、Sybrand J. T. Jonker、Denise N. Meyer、Göran Schulz、C. Duc Tran、Lars Eriksson、Kálmán J. Szabó
DOI:10.1039/c7sc05123a
日期:——
ketones and imines without any additives. Catalytic asymmetric propargylborylation of ketones is demonstrated with high stereoselectivity allowing for the synthesis of highly enantioenriched tertiary homopropargyl alcohols. The reaction is suitable for kinetic resolution of racemic allenylboronic acids affording alkynes with adjacentquaternarystereocenters.
A palladium-catalyzed multicomponent reaction (MCR) of propargylic carbonates with isocyanides is reported. Remarkably, the orderly insertion of isocyanides affords two types of valuable N-heterocyclic products (Z)-6-imino-4,6-dihydro-1H-furo[3,4-b]pyrrol-2-amines and (E)-5-iminopyrrolones in high yields. Systematic analysis of the reaction conditions indicates that the selectivity of these N-heterocyclic
报道了炔丙基碳酸酯与异氰酸酯的钯催化的多组分反应(MCR)。值得注意的是,有序插入异氰酸酯可提供两种有价值的N-杂环产物(Z)-6-亚氨基-4,6-二氢-1 H-呋喃[3,4- b ]吡咯-2-胺和(E) -5-亚氨基吡咯烷酮产量高。反应条件的系统分析表明,这些N-杂环产物的选择性可以通过配体和温度控制。
Borylation of Propargylic Substrates by Bimetallic Catalysis. Synthesis of Allenyl, Propargylic, and Butadienyl Bpin Derivatives
作者:Tony S. N. Zhao、Yuzhu Yang、Timo Lessing、Kálmán J. Szabó
DOI:10.1021/ja502792s
日期:2014.5.28
Bimetallic Pd/Cu and Pd/Ag catalytic systems were used for borylation of propargylic alcohol derivatives. The substrate scope includes even terminal alkynes. The reactions proceed stererospecifically with formal S(N)2' pathways to give allenyl boronates. Opening of propargyl epoxides leads to 1,2-diborylated butadienes probably via en allenylboronate intermediate.