Ligand-Promoted Pd-Catalyzed Oxime Ether Directed C–H Hydroxylation of Arenes
摘要:
An efficient Pd-catalyzed oxime ether directed ortho C-H hydroxylation of arenes under neutral conditions has been developed. The efficiency of this hydroxylation is significantly improved by a ligand. Oxone, an inexpensive, readily available, and safe reagent, was employed as terminal oxidant and oxygen source. The challenging electron-deficient substrates could also be monohydroxylated in high efficiency. Drug modification with this protocol was also successfully demonstrated.
Rhodium(III)-Catalyzed Synthesis of Cinnolinium Salts from Azobenzenes and Diazo Compounds
作者:Xiaohong Chen、Guangfan Zheng、Guoyong Song、Xingwei Li
DOI:10.1002/adsc.201800326
日期:2018.8.6
A Rh(III)‐catalyzed C−H activation of azobenzenes in the coupling with diazo compounds has been realized, providing a straightforward strategy to access functionalized cinnolinium triflates in high yields. This protocol features silver free mild reaction conditions and compatibility with diverse functional groups. The coupling proceeds via initial Rh(III)‐catalyzed C−H alkylation, followed by zinc
A removable oxime-assisted meta-C–H nitration of arenes is reported. Mechanistic investigations and DFT calculations reveal a new monomeric octahedral ruthenium(II) complex is responsible for the meta-selective nitration. Dioxygen as a cooxidant is crucial for achieving high conversion and good yields. Moreover, the utility of the present reaction protocol is further showcased by the late-stage modification
Rhodium(III)-catalyzed chelation-assisted C-H imidation of arenes via umpolung of the imidating reagent
作者:Guangfan Zheng、Jiaqiong Sun、Youwei Xu、Xukai Zhou、Hui Gao、Xingwei Li
DOI:10.1016/s1872-2067(20)63587-2
日期:2020.11
Abstract Rh(III)-catalyzed, chelation-assisted oxidative C−H imidation of arenes with N−H imide have been realized using PhI(OAc)2 as an oxidant. This transformation exhibits a broad substrate scope and tolerates various functional groups. The reaction proceeded via in situ generation of an iodine(III) imido. DFT calculations suggest that this oxidative imidaton system proceeds via a Rh(III)-Rh(V)-Rh(III)
An efficient Rh-catalyzed ortho-acrylation reaction for the synthesis of chalcones from O-methyl ketoximes and cyclopropenones via C-H bond activation has been described. This cross-coupling reaction exhibits high functional group tolerance and regioselectivity. A wide range of chalcone derivatives are obtained in moderate to good yields under mild conditions.
A fast and site-selective biaryl synthesis via dehydrogenative C–H/C–H arylation in a ball mill was developed. In this paper, both electron-deficient oximes and electron-rich anilides quickly and under mild conditions provided arylation with various arenes to give the biaryl products in high-level selectivity. Given the solventless mechanochemical conditions, the transformation obviated the use of