Reported herein is a visible‐light‐mediated radical approach to the α‐alkylation of ketones. This method exploits the ability of a nucleophilic organocatalyst to generate radicals upon SN2‐based activation of alkyl halides and blue light irradiation. The resulting open‐shell intermediates are then intercepted by weakly nucleophilic silyl enol ethers, which would be unable to directly attack the alkyl
Copper-Catalyzed Formal Dehydrogenative Coupling of Carbonyls with Polyfluoroarenes Leading to β-C–H Arylation
作者:Weilong Xie、Dongwook Kim、Sukbok Chang
DOI:10.1021/jacs.0c10904
日期:2020.12.9
We herein communicate a formal dehydrogenativecoupling of carbonyls with polyfluoroarenes enabled by Cu catalysis. Silyl enol ethers initially prepared from carbonyls are postulated to undergo the copper-mediated oxidative dehydrogenativecoupling with polyfluoroarenes via a radicalpathway. Including cyclic and linear ketones, aldehydes, and esters, a broad range of β-aryl carbonyl products were
我们在此交流了通过 Cu 催化实现的羰基与多氟芳烃的正式脱氢偶联。假设最初由羰基化合物制备的甲硅烷基烯醇醚通过自由基途径与多氟芳烃进行铜介导的氧化脱氢偶联。包括环状和线性酮、醛和酯在内,以高区域和立体选择性和优异的官能团耐受性有效地获得了广泛的 β-芳基羰基产物。
Reported herein is a photochemical cascade process that combines the excited-state and ground-state reactivity of chiral organocatalytic intermediates. This strategy directly converts racemic cyclopropanols and α,β-unsaturated aldehydes into stereochemically dense cyclopentanols with exquisite stereoselectivity. Mechanistic investigations have enabled elucidating the origin of the stereoconvergence
Synthesis of Highly Substituted Cyclohexenes via Mixed Lewis Acid-Catalyzed Diels−Alder Reactions of Highly Substituted Dienes and Dienophiles
作者:Michael E. Jung、David Ho、Hiufung V. Chu
DOI:10.1021/ol050361p
日期:2005.4.14
[reaction: see text] A high-yielding method is described for the rapid synthesis of very hindered cyclohexenes by the Diels-Alderreaction of hindered silyloxy dienes and dienophiles using the mixed Lewis acid catalyst system (AlBr(3)/AlMe(3)). Thus, reaction of the hindered diene 4 with various substituted enones gave good yields of the expected cycloadducts even though both partners are quite sterically
4-t-Butyldimethylsiloxy-l-benzopyrylium salt () was prepared in situ from chromone () and t-butyldimethylsilyl trillate and the salt reacted with enol silyl ethers, ketene silyl acetals and active methylene compounds to afford 2-substituted 4-t-butyldimethylsiloxy-2H-1-benzopyrans () in high yield. These products reacted with acid chlorides and an iminium salt to give 2,3-disubstituted 2,3-dihydro-