排序方式: 共有371条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
45.
46.
47.
48.
Yichen Wu Sbastien Bouvet Susana Izquierdo Alexandr Shafir 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(9):2643-2647
Among halogenated aromatics, iodoarenes are unique in their ability to produce the bench‐stable halogen(III) form. Earlier, such iodine(III) centers were shown to enable C?H functionalization ortho to iodine via halogen‐centered rearrangement. The broader implications of this phenomenon are explored by testing the extent of an unusual iodane‐directed para C?H benzylation, as well as by developing an efficient C?H coupling with sulfonyl‐substituted allylic silanes. Through the combination of the one‐shot nature of the coupling event and the iodine retention, multisubstituted arenes can be prepared by sequentially engaging up to three aromatic C?H sites. This type of iodine‐based iterative synthesis will serve as a tool for the formation of value‐added aromatic cores. 相似文献
49.
Yuye Chen Jingping Hu Lian‐Dong Guo Weihe Zhong Chengqing Ning Jing Xu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(22):7468-7472
The daphniphyllum alkaloids are a structurally fascinating and remarkably diverse family of natural products. General strategies for the chemical synthesis of their challenging architectures are highly desirable for efficiently accessing these intriguing alkaloids and addressing their pharmaceutical potential. Herein, a concise strategy designed to provide general and diversifiable access to various daphniphyllum alkaloids is described and utilized in the asymmetric synthesis of (?)‐himalensine A, which was accomplished in 14 steps. Key features of this strategy include a Cu‐catalyzed nitrile hydration, a Heck reaction to construct the challenging 2‐azabicyclo[3.3.1]nonane motif, a Meinwald rearrangement reaction, six, pot‐economic reactions, and the minimal use of protecting groups, which significantly improved the overall synthetic efficiency. 相似文献
50.
Christopher Cooze Raphael Dada Rylan J. Lundgren 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(35):12374-12379
Methods for the addition of unsaturated nucleophiles to carbonyls to generate Z‐olefin products remain rare and often require either alkyl borane or zinc reductants, limiting their utility. Demonstrated here is that formic acid mediates the Rh‐catalyzed, Z‐selective coupling of dienes and aldehydes. The process is distinguished by broad tolerance towards reducible or electrophilic groups. Kinetic analysis suggests that generation of the catalytically active Rh intermediate by ligand dissociation is the rate‐determining step. The rapid generation and trapping of Rh‐allyl intermediates is key to preventing chain‐walking isomerization events that plague related protocols. Insights gained through this study may have wider implications in selective metal‐catalyzed hydrofunctionalization reactions. 相似文献