作者:Andrew L. Kocen、Maurice Brookhart、Olafs Daugulis
DOI:10.1039/c7cc04953f
日期:——
We report a method for palladium-catalysed chain-running isomerization of terminal and internal alkenes. Using an air-stable 2,9-dimethylphenanthroline-palladium catalyst in combination with NaBAr4 promoter, olefins are converted to the most stable double bond isomer at −30 to 20 °C. Silyl enol ethers are readily formed from silylated allylic alcohols. Fluorinated substituents are compatible with the
Asymmetric Total Synthesis of (−)-Spirochensilide A, Part 1: Diastereoselective Synthesis of the ABCD Ring and Stereoselective Total Synthesis of 13(<i>R</i>)-Demethyl Spirochensilide A
construction of the ABCD ring system of spirochensilide A is described. The key steps of this synthesis are a semipinacol rearrangement reaction to stereoselectively construct the AB ring system bearing two vicinal quaternary chiral centers and a Co-mediated Pauson–Khand reaction to form the spiro-based bicyclic CD ring system. This chemistry leads to the stereoselective synthesis of 13(R)-demethyl spirochensilide
enolates as nucleophiles with aromatic aldehydes chemoselectively proceeded in the presence of silyl triflate and 2,2′-bipyridyl to produce β-siloxy aldehydes, while the aliphaticaldehydes were completely recovered. The unprecedented chemoselectivities depend on the reactivities of the pyridinium-type intermediatesderivedfrom the aromatic and aliphaticaldehydes.
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。
Polarity-Reversed Addition of Enol Ethers to Imines under Visible Light: Redox-Neutral Access to Azide-Containing Amino Acids
作者:Sen Yang、Shuangyu Zhu、Dengfu Lu、Yuefa Gong
DOI:10.1021/acs.orglett.9b03238
日期:2019.10.18
established for the construction of γ-azido aminoacids under visiblelight. This transformation features mild and redox-neutral conditions, affording a series of amino esters with excellent chemoselectivity. Preliminary mechanistic studies revealed that the addition of an oxyalkyl radical to imine is likely the rate-determining step. The obtained azido-containing amino esters could be successfully converted