甲肟基团已成为多种 C-H 官能化的多功能导向基团。尽管甲肟作为一种强大的功能手柄很重要,但通常需要将甲肟转化为母酮,但通常需要苛刻且官能团不耐受的反应条件。因此,甲肟的应用及其随后在后期转化为相应的酮可能会出现问题。在这里,我们提出了一组替代条件,以使用光激发硝基芳烃实现甲肟到母酮的温和且官能团耐受的转化。该方法的实用性体现在其在头孢内酯 D 的全合成中的应用。此外,还提供了通过同位素标记研究以及反应副产物分析获得的这种转化的机制见解。
Scope and selectivity in palladium-catalyzed directed C–H bond halogenation reactions
作者:Dipannita Kalyani、Allison R. Dick、Waseem Q. Anani、Melanie S. Sanford
DOI:10.1016/j.tet.2006.06.075
日期:2006.12
Palladium-catalyzed ligand directed C–H activation/halogenation reactions have been extensively explored. Both the nature of the directing group and the substitution pattern on the arene ring of the substrate lead to different reactivity profiles, and often different and complementary products, in the presence and absence of the catalyst.
Use of Strain-Release for the Diastereoselective Construction of Quaternary Carbon Centers
作者:Tobias Pinkert、Mowpriya Das、Malte L. Schrader、Frank Glorius
DOI:10.1021/jacs.1c03492
日期:2021.5.26
formation of quaternary carbon centers with excellent diastereoselectivity via a strain-release protocol. An organometallic species is generated by Cp*Rh(III)-catalyzed C–H activation, which is then coupled with strained bicyclobutanes (BCBs) and a prochiral carbon electrophile in a three-component reaction. This work illustrates a rare example of BCBs in transition metal catalysis and demonstrates their
Palladium-Catalyzed Oxidative Ethoxycarbonylation of Aromatic C−H Bond with Diethyl Azodicarboxylate
作者:Wing-Yiu Yu、Wing Nga Sit、Kin-Man Lai、Zhongyuan Zhou、Albert S. C. Chan
DOI:10.1021/ja710555g
日期:2008.3.1
(DEAD) together with Oxone or K2S2O8. Substrates such as 2-arylpyridines, pyrrolidinone, acetylindoline, quinoline, and oximes were ethoxycarbonylated with excellent chemo- and regioselectivities. The catalytic reaction is probably initiated by chelation-assisted cyclopalladation of the ortho-C−H bond. Preliminary studies suggested that reactive ethoxyacyl radicals generated from thermal decomposition
A novel Rh(III)-catalyzed C–H bond amination with the simultaneous release of a formyl group at distal positions is realized employing anthranil as a new type of C–Hamination reagent. This chemistry provides an efficient protocol for the synthesis of 2-acyl diarylamines, which are important structural motifs in many bioactive compounds. This new type of C–Hamination reagent possesses the advantages
Palladium-Catalyzed Chelation-Assisted Aromatic C–H Nitration: Regiospecific Synthesis of Nitroarenes Free from the Effect of the Orientation Rules
作者:Wei Zhang、Shaojie Lou、Yunkui Liu、Zhenyuan Xu
DOI:10.1021/jo400594j
日期:2013.6.21
ortho-nitration of aryl C–H bond is described. A range of azaarenes such as 2-arylquinoxalines, pyridines, quinoline, and pyrazoles were nitrated with excellent chemo- and regioselectivity. Using the O-methyl oximyl group as a removable directing group, the regiospecific synthesis of a variety of o-nitro aryl ketones was achieved starting from aryl ketones via a three-step process involving the Pd-catalyzed