<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。
Regio- and Stereoselective Synthesis of 1,2-Dihaloalkenes Using In-Situ-Generated ICl, IBr, BrCl, I2, and Br2
作者:Xiaojun Zeng、Shiwen Liu、Yuhao Yang、Yi Yang、Gerald B. Hammond、Bo Xu
DOI:10.1016/j.chempr.2020.03.011
日期:2020.4
2-trans-dihalogenation of alkynes with an unprecedented substrate scope and exclusive regio- and stereoselectivity. This versatile dihalogenation system—a combination of NX1S electrophile and alkali metal halide (MX2) in acetic acid—is applicable for diverse categories of alkynes (electron-rich or poor alkynes, internal and terminalalkynes, or heteroatoms such as O-, N-, S-substituted alkynes). The hydrogen
我们描述了炔烃的无催化剂的1,2-反式二卤代反应,具有空前的底物范围和排他性和立体选择性。这种多功能的二卤化系统-NX 1 S亲电试剂和乙酸中的碱金属卤化物(MX 2)的组合-适用于各种类型的炔烃(富电子或弱炔烃,内部和末端炔烃,或杂原子,例如O- ,N-,S-取代的炔烃)。氢键供体溶剂乙酸对于就地生成X 1 X 2亲电试剂(包括ICl,IBr,BrCl,I 2和Br 2)是必不可少的。
Stereochemistry of chlorination and chloroiodination of alkylphenylacetylenes by CuCl2
作者:Sakae Uemura、Akira Onoe、Masaya Okano
DOI:10.1039/c39750000925
日期:——
Reaction of alkylphenylacetylenes, PhCCR (R = H or alkyl)(1), with CuCl2–LiCl or CuCl2–I2 in acetonitrile gives the corresponding dihalogenoalkenes in good yields; E-addition is favoured except in the chlorination of (1, R = But) where Z-addition predominates.