Chemoselective Bromodeboronation of Organotrifluoroborates Using Tetrabutylammonium Tribromide: Application in (Z)-Dibromoalkene Syntheses
摘要:
Tetrabutylammonium tribromide (TBATB) has been found to be a unique bromodeboronation reagent for organotrifluoroborates. When compared to previously reported bromodeboronation methods, the mild and metal-free reaction conditions tolerate a wider range of functional groups. High regio- and chemoselectivity are observed in the presence of both unsaturated carbon-carbon bonds and aldehyde functional groups. An efficient synthetic route to (Z)-dibromoalkenes from terminal alkynes has been developed using the TBATB-mediated bromodeboronation as a key step.
<scp>TEMPO‐Regulated</scp>Regio‐ and Stereoselective<scp>Cross‐Dihalogenation</scp>with Dual Electrophilic X<sup>+</sup>Reagents
作者:Yi Kong、Tongxiang Cao、Shifa Zhu
DOI:10.1002/cjoc.202100472
日期:2021.11
method could enable wide applications in organic synthesis, which was exemplified by divergent synthesis of two pharmaceuticals. Detailed mechanistic investigations via radical clock reaction, pinacol ring expansion and Hammett experiments were conducted, which confirmed the intermediacy of halonium ion. In addition, a dynamic catalytic model based on the versatile catalytic role of TEMPO was proposed
TEMPO 催化的交叉二卤化反应是通过氧化还原调节双亲电 X +试剂的复杂系统而建立的。形式上,ICl的,氯化溴,我2和Br 2产生在-原位,这使高区域选择性或立体选择性获得的iodochlorination,bromochlorination和均-二卤化产物无数与功能性的宽光谱。该方法条件温和,操作简单,可广泛应用于有机合成,例如两种药物的发散合成。通过详细的机械调查进行了自由基钟反应、频哪醇扩环和哈米特实验,证实了卤离子的中介作用。此外,提出了一种基于 TEMPO 多功能催化作用的动态催化模型来解释选择性结果。
A Domino Copper-Catalyzed C-N and C-O Cross-Coupling for the Conversion of Primary Amides into Oxazoles
作者:Frank Glorius、Kerstin Schuh (née Müller)
DOI:10.1055/s-2007-983782
日期:2007.7
A variety of oxazoles can efficiently be prepared, in a single step and in good yield, from primaryamides and 1,2-dihaloalkenes using copper-catalysis. This new method allows the re-gioselective formation of a range of substituted oxazoles. The required 1,2-dihaloalkenes can prepared by simple treatment of alkynes with elemental bromine or iodine.
Halodeboronation of organotrifluoroborates using tetrabutylammonium tribromide or cesium triiodide
作者:Min-Liang Yao、George W. Kabalka、David W. Blevins、Marepally Srinivasa Reddy、Li Yong
DOI:10.1016/j.tet.2012.03.016
日期:2012.5
Halodeboronation of organotrifluoroborates using commercially available tetrabutylammoniumtribromide (TBATB) or cesium triiodide in aqueous medium is reported. The mild, transition metal-free method has proven to be tolerant of a wide range of functional groups. High regio- and chemoselectivity are observed. Two synthetic routes to (Z)-dibromoalkenes from alkynes, through stereodefined (Z)-2-brom
Acetylenes were stereoselectively brominated with molecular bromine adsorbed on graphite in dichloromethane to produce (E)-α,β-dibromoalkenes; isomerization of the E-isomer to the Z-isomer, usually catalyzed by bromine, did not occur in the presence of graphite.
Abstract Bromination of alkenes and alkynes has efficiently been carried out at room temperature in short reaction times using KBr and diacetoxy iodobenzene in CH2Cl2-H2O (1:1) to prepare the corresponding trans-dibromo compounds in excellent yields.