A Carbene Strategy for Progressive (Deutero)Hydrodefluorination of Fluoroalkyl Ketones
作者:Xiaolong Zhang、Xinyu Zhang、Qingmin Song、Paramasivam Sivaguru、Zikun Wang、Giuseppe Zanoni、Xihe Bi
DOI:10.1002/anie.202116190
日期:2022.2.7
A carbene strategy for the sequential (deutero)hydrodefluorination of fluoroalkyl ketones is reported. This method allowed for the controllable preparation of difluoroalkyl- and monofluoroalkyl ketones from aryl- and alkyl-substituted perfluoroalkyl ketones in high yield with excellent functional group tolerance.
(2) with a slope of unity over a wide range (108 in reactivity) of substituents from p-MeO to unsubstituted derivatives. The substituent effect on the solvolysis of 1 should be closer to that on the solvolysis of 2, rather than to the σ+ substituent effect. The ρ value for this system was estimated to be identical to the value of −6.3 assigned for 2, and the r value in the LArSR correlation to be comparable
Defluorinative Carboimination of Trifluoromethyl Ketones
作者:Xiaolong Zhang、Yongquan Ning、Zhaohong Liu、Shuang Li、Giuseppe Zanoni、Xihe Bi
DOI:10.1021/acscatal.2c02434
日期:2022.8.5
intramolecular cascade process by integrating successive cleavage of the C–Fbond and formation of C–C and C═N bonds on a single molecule entity, which differs relevantly from the stepwise mechanism of reported carbodefluorination of CF3 groups. Mechanistic studies disclose that silver catalysis plays a critical role, particularly in the stages of C–Fbondcleavage and aza-Claisen rearrangement.
Treatment of arylketene bis(methylthio)acetal monoxide with trifluoromethanesulfonic anhydride leads to ring-closure to afford 2-methylthiobenzo-[b]thiophene in high yield. The reaction is useful for synthesizing multisubstituted benzo[b]thiophenes.
Substituent Effects. XIX. Solvolysis of 1-Aryl-1-(trifluoromethyl)ethyl Tosylates
solvolysis of 1-aryl-1-(trifluoromethyl)ethyl tosylates were determined in 80% aqueous ethanol for a series of substituents. The Brown ρ+σ+ treatment fails to give a simple linear plot, but all the p-π-donors deviate upward from the meta-correlation line. On the other hand, the Yukawa–Tsuno LArSR Eq. gives a linear correlation over the whole range of substituents, log(k⁄k0)=−6.287(σ°+1.388Δ\barσR+), with
1-芳基-1-(三氟甲基)乙基甲苯磺酸酯的溶剂分解速率在 80% 乙醇水溶液中测定一系列取代基。Brown ρ+σ+ 处理未能给出简单的线性图,但所有 p-π-供体都从元相关线向上偏离。另一方面,Yukawa-Tsuno LArSR Eq。在整个取代基范围内给出线性相关性,log(k⁄k0)=−6.287(σ°+1.388Δ\barσR+),具有出色的精度。α-CF3 对碳正离子中间体的强烈不稳定似乎仅反映在极高的 r 值上,而不反映在取代基效应的 ρ 值上。这与文献中基于简单布朗 σ+ 处理给出的该反应的结论严重冲突。该反应具有极高的共振需求 r=1.4,应该远远超出简单的 Brown σ+ 分析的范围。改变共振需求应该是充分描述关于共轭碳正离子反应的取代基效应的基本要求。