Borylative Heterocyclization without Air-Free Techniques
作者:Chao Gao、Shuichi Nakao、Suzanne A. Blum
DOI:10.1021/acs.joc.0c01096
日期:2020.8.21
In contrast to previously reported borylative heterocyclization methods, a reaction here proceeds without air-free techniques to access synthetically useful borylated thiophenes, benzothiophenes, and isocoumarins. A comparison of stability/decomposition rates in air of several catecholboronic ester (Bcat) compounds derived from different heterocycle cores showed a strong dependence on the heterocycle
Gold(I)-Catalyzed Glycosylation with Glycosyl<i>ortho</i>-Alkynylbenzoates as Donors: General Scope and Application in the Synthesis of a Cyclic Triterpene Saponin
coupling with the poorly nucleophilic amides gives satisfactory yields. Moreover, excellent α‐selective glycosylation with a 2‐deoxysugar donor and β‐selective sialylation have been realized. Application of the present glycosylation protocol in the efficient synthesis of a cyclic triterpene tetrasaccharide have further demonstrated the versatility and efficacy of this new method, in that a novel chemoselective
Benziodoxole Triflate as a Versatile Reagent for Iodo(III)cyclization of Alkynes
作者:Bin Wu、Junliang Wu、Naohiko Yoshikai
DOI:10.1002/asia.201701530
日期:2017.12.14
Hyperactive: A benziodoxole triflate promotes iodo(III)cyclization of alkynes tethered to a variety of nucleophilic moieties, affording benziodoxole-appended (hetero)arenes such as benzofurans, benzothiophenes, isocoumarins, indoles, and polyaromatics. These unprecedented (hetero)aryl-IIII compounds are easy to purify, air- and thermally stable, and amenable to various synthetic transformations.
<scp>Copper‐Catalyzed</scp>
Modular Access to
<scp>
<i>N</i>
‐Fused
</scp>
Polycyclic Indoles and
<scp>5‐Aroyl</scp>
‐pyrrol‐2‐ones
<i>via</i>
Intramolecular N—H/C—H Annulation with Alkynes: Scope and Mechanism Probes
作者:Yan‐Hua Liu、Hong Song、Chi Zhang、Yue‐Jin Liu、Bing‐Feng Shi
DOI:10.1002/cjoc.202000246
日期:2020.12
Copper‐catalyzed intramolecular N—H/C—H annulation with alkynes has been developed. A variety of densely functionalized heterocycles, such as pyrrolo[1,2‐a]indoles, indolo[1,2‐c]quinazolin‐2‐ones, oxazolo[3,4‐a]indoles, and imidazo[1,5‐a]indoles, were synthesized in an atom‐ and step‐economical manner, owing to the high modularized feature of aniline moiety, the linker moiety, as well as the alkyne
已经开发了使用炔烃的铜催化分子内NH / CH环合反应。各种稠密官能化的杂环,如吡咯并[1,2- a ]吲哚,吲哚并[1,2 - c ]喹唑啉-2-酮,恶唑并[3,4- a ]吲哚和咪唑[1,5-由于苯胺部分,连接子部分和炔烃部分具有高度模块化的特征,因此以原子和分步经济的方式合成了α ]吲哚。通过简单地改变从二氧化剂叔将过氧化叔丁基(DTBP)转化为2,2,6,6-四甲基哌啶-1-氧基(TEMPO),该反应很容易转化为氨氧化途径,该途径从TEMPO夺取一个氧原子以生成5-芳酰基吡咯2个 机理实验表明,乙烯基自由基参与了该反应,而酰胺基自由基引发的自由基级联反应可能是造成这种转变的原因。
Ligand-free hydroboration of alkynes catalyzed by heterogeneous copper powder with high efficiency
作者:Jie Zhao、Zhiqiang Niu、Hua Fu、Yadong Li
DOI:10.1039/c3cc48670b
日期:——
Regioselective hydroboration of terminal and internal alkynes is realized by using copper powder (0.3–1 μm) as a catalyst without any ligand.