Rhodium(<scp>iii</scp>)-catalyzed asymmetric [4+1] spiroannulations of <i>O</i>-pivaloyl oximes with α-diazo compounds
作者:Lincong Sun、Bingxian Liu、Yanlian Zhao、Junbiao Chang、Lingheng Kong、Fen Wang、Wei-Qiao Deng、Xingwei Li
DOI:10.1039/d1cc02888j
日期:——
Chiral RhIII catalysts can catalyze the asymmetric [4+1] spiroannulation of O-pivaloyl oximes with α-diazo homophthalimides under redox-neutral and acid/base-neutral conditions, leading to formation of chiral spirocyclic imines as a result of C–H activation and N–O cleavage. The reaction proceeded with high efficiency and features broad substrate scope, mild reaction conditions, and high to excellent
dihydrobenzofuran-fused pyridones in moderate to good yields with good functional group compatibility. The reaction likely involves a radical relay annulation, leading to the ring opening of the lactone moiety of the coumarins, and simultaneous formation of three new bonds. The investigation of photoluminescent properties reveals that several obtained compounds may have potential as fluorescent materials.
A useful Cu-catalyzed cycloaddition protocol for the construction of benzene rings has been achieved. The reactions, utilizing readily available oximes and maleimides as starting materials, proceed under mild reaction conditions to generate a series of structurally interesting fused-phthalimides that are difficult to be prepared by conventional methods.
Synthesis of Fused-Pyrazines <i>via</i>
Palladium-Catalyzed Double Benzyl Isocyanide Insertion and Cross-Dehydrogenative Coupling
作者:Gopal Chandru Senadi、Bing-Chun Guo、Yu-Ching Chang、Wan-Ping Hu、Jeh-Jeng Wang
DOI:10.1002/adsc.201701202
日期:2018.2.1
palladium‐catalyzed cascade reaction has been realized for the synthesis of 5H‐pyrrolo[2,3‐b]pyrazines and 5H‐pyrazino[2,3‐b]indoles from benzyl isocyanide by choosing o‐pivaloyloximes or o‐iodoanilines as a suitable substrate. The key steps involved are (i) oxidative addition of palladium through N–O or C–I cleavage; (ii) migratory double isocyanide insertion; and (iii) cross‐dehydrogenativecoupling. Notable
通过选择邻-吡咯并酮肟或邻-碘苯胺,已实现了钯催化的级联反应,可从异氰酸苄酯合成5 H-吡咯并[2,3- b ]吡嗪和5 H-吡嗪并[2,3- b ]吲哚。作为合适的基材。涉及的关键步骤是(i)通过N-O或C-I裂解氧化钯的加成;(ii)迁移性双异氰酸酯插入;(iii)交叉脱氢偶联。显着的特征是良好的官能团耐受性以及三个C–C和一个C–N键的形成。
Base-Promoted [3+2]-Annulation of Oxime Esters and Aldehydes for Rapid Isoxazoline Formation
作者:Huawen Huang、Feifei Li、Zhenhua Xu、Jinhui Cai、Xiaochen Ji、Guo-Jun Deng
DOI:10.1002/adsc.201700730
日期:2017.9.18
A base‐promoted [3+2]‐annulation of ketoxime esters and aldehydes is disclosed for the facile and rapid synthesis of 3,5‐disubstituted and 3,4,5‐trisubstituted isoxazolines. The key to our success is the pivalate leaving group of the oxime substrates, combined with cesium carbonate as promoter. This chemistry allows the assembly of a vast array of isoxazoline derivatives under simple base conditions