Encounter of an Inferior Intramolecular Cyclization in an Approach toward the Synthesis of 10-Oxo-2-thia[3.2]metacyclophane: Preparation of Two Isomeric Dioxo-2,19-dithia[3.2.3.2]metacyclophanes
作者:Shun Wang、Nanjundappa Lokesh、Johnny Hioe、Ruth M. Gschwind、Burkhard König
DOI:10.1039/c9sc00711c
日期:——
carbonyl groups in a single reaction are less explored. Here, we report a photoredox-catalysis that uses B2pin2 as terminal reductant and oxygen trap allowing for deoxygenative olefination of aromaticaldehydes under mild conditions. This strategy provides access to a diverse range of symmetrical and unsymmetrical alkenes with moderate to high yield (up to 83%) and functional-group tolerance. To follow
羰基-羰基烯化反应,即 McMurry 反应,代表了构建烯烃的有力策略。然而,在单个反应中直接偶联两个羰基的催化变体的探索较少。在这里,我们报告了一种使用 B 2 pin 2的光氧化还原催化作为末端还原剂和氧阱,允许在温和条件下对芳族醛进行脱氧烯化。该策略提供了获得各种对称和不对称烯烃的途径,具有中等至高产率(高达 83%)和官能团耐受性。为了遵循反应途径,进行了一系列实验,包括自由基抑制、氘标记、荧光猝灭和循环伏安法。此外,结合 NMR 研究和 DFT 计算来检测和分析三种活性中间体:环状三元阴离子物质、α-氧硼基碳负离子和 1,1-苄基二硼酸酯。基于这些结果,我们提出了一种 C C 键生成机制,涉及顺序自由基硼化、“bora-Brook”重排、B 2pin 2介导的脱氧和硼-维蒂希过程。
Energy-Transfer-Mediated Photocatalysis by a Bioinspired Organic Perylenephotosensitizer HiBRCP
triplet energy was greatly improved, and then, it could markedly promote the efficient geometrical isomerization of alkenes from the E-isomer to the Z-isomer. Moreover, it was also effective for energy-transfer-mediated organometallic catalysis, which allowed realization of the cross-coupling of aryl bromides and carboxylic acids through efficient energy transfer from HiBRCP to nickel complexes. Thus, the
ZEOLITE-CuNaY CATALYZED DECOMPOSITION OF ARYLDIAZOMETHANE
作者:Makoto Onaka、Hiroshi Kita、Yusuke Izumi
DOI:10.1246/cl.1985.1895
日期:1985.12.5
Decomposition of aryldiazomethanes is catalyzed by copper ion-exchanged Y-type zeolite to afford cis-1,2-diarylethylenes in high selectivity. The catalytic activity and selectivity are found to be affected by the exchange level of copper ions in zeolite and the solvent used.
Formation of Bromocarbenium Bromide Ion Pairs in the Electrophilic Bromination of Highly Reactive Olefins in Chlorinated Aprotic Solvents
作者:Giuseppe Bellucci、Cinzia Chiappe、Giacomo Lo Moro
DOI:10.1021/jo9620526
日期:1997.5.1
rate-determining nucleophilic attack by bromide on the olefin-Br(2) pi-complex. The data related to the bromination of the more activated methoxystilbenes are rationalized considering that, for these olefins, even in aprotic solvents, the ionization of the initially formed 1:1 pi-complex to a bromocarbenium bromide ionpair can compete both with the formation of a bromonium-tribromide ionpair and with the
Convenient and Stereoselective Synthesis of Symmetrical (E)-Stilbenes via Homocoupling of 1,3-Dibenzylbenzotriazolium Bromides
作者:Xiaohui Xiao、Daqin Lin、Shuitian Tong、Hong Luo、Yinfeng He、Hailan Mo
DOI:10.1055/s-0030-1260814
日期:2011.7
Using NaH as the base and DMSO as the solvent, a series of symmetric (E)-stilbenes were prepared in good yields via the homocoupling of 1,3-dibenzylbenzotriazolium bromides at room temperature.
以 NaH 为碱基,DMSO 为溶剂,在室温下通过 1,3-二苄基苯并三唑溴化物的均偶联反应制备了一系列对称 (E)- 二苯乙烯,收率良好。