Enantioselective Total Synthesis of (−)-Walsucochin B
摘要:
The first enantioselective total synthesis of the structurally unique nortriterpenoid (-)-walsucochin B has been accomplished through the cationic polyolefin cyclization initiated by chiral epoxide. The core framework and the stereocenters in the natural product were all constructed in this step. A site-selective, late-stage free-radical halogenation and Seyferth-Gilbert homologation was adopted to install the acetylene moiety to synthesize the phenylacetylene. The absolute configuration of walsucochin B was confirmed through enantioselective total synthesis.
Pd‐Colloids‐Catalyzed/Ag
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O‐Oxidized General and Selective Esterification of Benzylic Alcohols
作者:Vaibhav Sable、Jagrut Shah、Anuja Sharma、Anant R. Kapdi
DOI:10.1002/asia.201900566
日期:2019.8
Palladium colloids obtained from the degradation of Hermann–Beller palladacycle proved to be an efficient catalytic system in combination with silver oxide as a selective oxidant for the oxidative esterification of differently substituted benzyl alcohols in MeOH as solvent. Excellent reactivity exhibited by the catalytic system also allowed the alcoholic coupling partner to be changed from MeOH to
Applicability of aluminum amalgam to the reduction of arylnitro groups
作者:Paige J. Monsen、Frederick A. Luzzio
DOI:10.1016/j.tetlet.2020.152575
日期:2020.11
compounds with various functionality were treated with freshly-prepared aluminum amalgam in THF/water solution and resulted in the corresponding arylamines. The Al(Hg)-mediated reductions are relatively rapid with consumption of the amalgam and disappearance of starting material occurring over 20–30 min. The workup of the reductions involves only removal of the insoluble by-products by filtration followed
Direct <i>N</i>-H/<i>N</i>-Me Aziridination of Unactivated Olefins Using <i>O</i>-(Sulfonyl)hydroxylamines as Aminating Agents
作者:Shekh Sabir、Chandra Bhan Pandey、Ajay K. Yadav、Bhoopendra Tiwari、Jawahar L. Jat
DOI:10.1021/acs.joc.8b01673
日期:2018.10.5
methods are devoted to their activated counterparts. Herein, we have developed a highly efficient Rh(II)-catalyzed method for the direct preparation of unactivated aziridines from olefins using O-(sulfonyl)hydroxylamines as the aminating agent. The reactions proceed with a high stereospecificity.
NXS, Morpholine, and HFIP: The Ideal Combination for Biomimetic Haliranium-Induced Polyene Cyclizations
作者:Andreas M. Arnold、Alexander Pöthig、Markus Drees、Tanja Gulder
DOI:10.1021/jacs.8b00113
日期:2018.3.28
contrast to Nature that accomplishes polyenecyclizations seemingly with ease, such transformations are difficult to conduct in the lab. In our program dealing with the development of selective halogenations of alkenes, we now asserted that standard X+ reagents are perfectly suited for the biomimetic cation-π cyclization of both electron rich and poor linear polyenes in the presence of the Lewis base
Metal- and Additive-Free Intermolecular Aziridination of Olefins Using N-Boc-O-tosylhydroxylamine
作者:Jawahar L. Jat、Bhoopendra Tiwari、Dinesh Chandra、Puneet Kumar、Vikram Singh
DOI:10.1055/a-1879-7974
日期:2022.10
A metal and additive-free stereospecific direct N-H and N-Me aziridination of inactivated olefins is disclosed using N-Boc-O-tosylhydroxylamine (TsONHBoc) as an aminating agent in hexafluoroisopropanol (HFIP). The use of TsONHBoc, which generates the free aminating agent in situ under the reaction conditions, has several inherent advantages over other similar agents, such as low cost, easy access