Palladium(0)-Catalyzed Cross-Coupling of 1,1-Diboronates with Vinyl Bromides and 1,1-Dibromoalkenes
作者:Huan Li、Zhikun Zhang、Xianghang Shangguan、Shan Huang、Jun Chen、Yan Zhang、Jianbo Wang
DOI:10.1002/anie.201407000
日期:2014.10.27
Palladium‐catalyzed cross‐coupling reactions of 1,1‐diboronates with vinylbromides and dibromoalkenes were found to afford 1,4‐dienes and allenes, respectively. These reactions utilize the high reactivities of both 1,1‐diboronates and allylboron intermediates generated in the initial coupling.
We describe the facile and efficient metal-promoted reduction of C–Br bonds of gem -dibromides. When the reaction is mediated by indium, the corresponding vinyl bromides are obtained in good yields and high E -stereoselectivities. Alternatively, when the reduction is mediated by samarium diiodide, vinyl bromides are obtained in moderate yields and good Z -selectivities.
我们描述了宝石二溴化物的 C-Br 键的简单有效的金属促进还原。当反应由铟介导时,以良好的收率和高 E 立体选择性获得相应的乙烯基溴。或者,当还原由二碘化钐介导时,乙烯基溴以中等产率和良好的 Z 选择性获得。
Readily Removable Directing Group Assisted Chemo- and Regioselective C(sp<sup>3</sup>)H Activation by Palladium Catalysis
作者:Yun-Fei Zhang、Hong-Wei Zhao、Hui Wang、Jiang-Bo Wei、Zhang-Jie Shi
DOI:10.1002/anie.201505932
日期:2015.11.9
Currently used directing groups for selective aliphatic β‐functionalization of carbonyl compounds show excellent reactivity and selectivity with an amide as a linker. Described herein is 2‐piconimide, used for the first time with commercially available 2‐picolinamide/2‐picolic acid as precursors, to directCH arylation/alkenylation by palladium catalysis. The directing group is essential for promoting
Cooperative <i>N</i>-Heterocyclic Carbene/Palladium-Catalyzed Umpolung 1,4-Addition of Vinyl Bromides to Enals
作者:Bo Ling、Wenjun Yang、Yan-En Wang、Jianyou Mao
DOI:10.1021/acs.orglett.0c03654
日期:2020.12.18
A highly stereoselective umpolung 1,4-addition of vinylbromides to enals is enabled by NHC/palladium cooperative catalysis, generating various valuable γ,δ-unsaturated carbonyl derivatives in excellent yields (up to 90%). A detailed mechanism investigation indicates the NHC act as both organocatalyst and ligand for palladium during this system.
Construction of Phenanthrenes and Chrysenes from β-Bromovinylarenes via Aryne Diels–Alder Reaction/Aromatization
作者:Vikram Singh、Ram Subhawan Verma、Anil K. Khatana、Bhoopendra Tiwari
DOI:10.1021/acs.joc.9b01644
日期:2019.11.1
A highly efficient transition-metal-free general method for the synthesis of polycyclic aromatic hydrocarbons like phenanthrenes and chrysenes (and tetraphene) from β-bromovinylarenes and arynes has been developed. The reactions proceed via an aryne Diels-Alder (ADA) reaction, followed by a facile aromatization. This is the first report on direct construction of chrysenes (and tetraphene) using the