已经通过吡啶-2-硫代氧羰基(PTOC)竞争动力学方法在单个浓度点上确定了壬基从20种N-杂环卡宾和硼烷(NHC-硼烷)的络合物中提取氢的速率常数。速率常数的范围是从<1×10 4到8×10 4 M -1 s -1。它们几乎不依赖于卡宾核的电子性质,但是存在随着卡宾N取代基尺寸的减小而增加速率常数的趋势。已经鉴定出两种有希望的具有小的N取代基的新试剂(R = Me)。
Radical Borylation/Cyclization Cascade of 1,6-Enynes for the Synthesis of Boron-Handled Hetero- and Carbocycles
作者:Shi-Chao Ren、Feng-Lian Zhang、Jing Qi、Yun-Shuai Huang、Ai-Qing Xu、Hong-Yi Yan、Yi-Feng Wang
DOI:10.1021/jacs.7b01889
日期:2017.5.3
construct boron-handled cyclic molecules was developed based on a radical borylation/cyclization cascade of 1,6-enynes. The process was initiated by the chemo- and regio-controlled addition of an N-heterocyclic carbene-boryl radical to an alkene or alkyne, followed by ring closure to afford boron-substituted cyclic skeletons. Further molecular transformations of the cyclic products to synthetically
Regioselective radical hydroboration of electron-deficient alkenes: synthesis of α-boryl functionalized molecules
作者:Yun-Shuai Huang、Jie Wang、Wan-Xin Zheng、Feng-Lian Zhang、You-Jie Yu、Min Zheng、Xiaoguo Zhou、Yi-Feng Wang
DOI:10.1039/c9cc06506g
日期:——
various electron-deficient alkenes is achieved by the employment of an NHC–boryl radical. A range of α-borylated nitriles, trifluoromethyl molecules, phosphonates, sulfones, and gem-diboron compounds have been prepared from readily available startingmaterials. Further synthetic applications of these products are also demonstrated.
In this Communication, we report an unprecedented β‐regioselective radical inverse hydroboration (compared with ionic hydroboration) of α,β‐unsaturated amides with NHC‐BH3 enabled by photoredox catalysis. Density functional theory (DFT) calculations show that the unique photoredox cycle is a key factor to control the β‐regioselective radical hydroboration, by lowering the energy barrier in comparison
The first catalytic inverse hydroboration of imines with N‐heterocyclic carbene (NHC) boranes has been realized by means of cooperative organocatalysis and photocatalysis. This catalytic combination provides a promising platform for promoting NHC‐boryl radical chemistry under sustainable and radical‐initiator‐free conditions. The highly important functional‐group compatibility and possible application
Borylative Radical Cyclizations of Benzo[3,4]cyclodec‐3‐ene‐1,5‐diynes and N‐Heterocyclic Carbene‐Boranes
作者:Takashi Watanabe、Daisuke Hirose、Dennis P. Curran、Tsuyoshi Taniguchi
DOI:10.1002/chem.201700689
日期:2017.4.24
Borylative radical cyclization of benzo[3,4]cyclodec‐3‐ene‐1,5‐diynes to provide 5‐borylated 6,7,8,9‐tetrahydrobenzo[a]azulenes has been developed. The experimental results suggest that the reaction proceeds by a radical chain mechanism, in which di‐tert‐butyl hyponitrite (TBHN) works as a good radical initiator to form borylradicals from N‐heterocyclic carbene–boranes (NHC‐boranes). The present reaction
已开发出苯并[3,4] cyclodec-3-烯-1,5-二炔的硼酸自由基环化反应,以提供5硼酸化的6,7,8,9-四氢苯并[ a ] azulenes。实验结果表明,反应是通过自由基链机理进行的,其中二叔丁基亚硝酸盐(TBHN)作为良好的自由基引发剂,可从N杂环卡宾-硼烷(NHC-硼烷)形成硼自由基。本反应是罕见的模型,其说明了向炔烃中加硼基。