Single-electron reduction of chalcones to the respective radical anions is a useful technique to activate these molecules toward subsequent transformations. Herein, a metal-free photocatalytic version of chalcones reduction in the presence of triethanolamine as a convenient electron donor and using heterogeneous carbon nitride visible-light photocatalyst is presented. The reaction proceeds via a long-lived
查耳酮单电子还原为相应的自由基阴离子是激活这些分子进行后续转化的有用技术。在此,提出了在三乙醇胺作为方便的电子供体存在下并使用非均相氮化碳可见光光催化剂还原查尔酮的无金属光催化方案。该反应通过异质有机半导体的长寿命自由基种类进行。研究了反应的范围,并研究了查耳酮自由基偶联的区域选择性。(1)十个查耳酮生成选择性多取代的环戊醇,分离产率为31-73%;(2)两个带有电子给体基团的查耳酮,4-MeOC 6 H 4和2-噻吩基分别产生β-酮二烯,分离产率分别为42%和53%。(3)五氟苯基取代的查尔酮仅给出自由基偶联的产物,然后从三乙醇胺-己烷-1,6-二酮中转移氢,分离出产率为65%。两种不同查耳酮混合物的还原性交叉环二聚反应区域选择性地进行,形成了四种可能产物中的一种。通过循环伏安法和线性扫描伏安法研究了该机理,表明该反应通过质子偶联电子转移进行。
Nouvelle méthode de création de la liaison silicium-carbone à partir de chlorosilanes VIII. C-silylation d'aldehydes et de cétones α-éthylèniques
作者:R. Calas、J. Dunoguès、M. Bolourtchian
DOI:10.1016/s0022-328x(00)84770-1
日期:1971.1
The trimethylchlorosilane/magnesium/hexamethylphosphoric triamide system reacts with various α-ethylenic aldehydes and ketones to give the 1,4-addition compound of two trimethylsilyl groups. This, after hydrolysis, leads to aldehydes and ketones, C-silylated in β position with respect to the carbonyl group. The corresponding alcohols have been prepared.
[2 + 4] Annulation of Alkyl(phenyl)phosphinic Chlorides with Enones: Stereoselective Synthesis of δ-Phosphinolactones
作者:Xin Yuan、Xuan Ke、Jiaxi Xu
DOI:10.1021/acs.orglett.2c03878
日期:2022.12.16
Various δ-phosphinolactones (δ-phostines) are efficiently and diastereospecifically synthesized in good to excellent yields from direct [2 + 4] annulation of alkyl(phenyl)phosphinic chlorides and α,β-enones in the presence of LiHMDS. The annulation involves deprotonation, Michael addition, and nucleophilic substitution and features readily available materials, good to excellent yields, diastereospecificity