利用Cu(OAc)2- [Cp * RhCl 2 ] 2双金属催化体系,开发了一种由芳基酮O-乙酰基肟和内部炔烃合成氮杂杂环的方法。该反应在具有广泛取代基的肟的反-和顺-异构体上进行。Cu-Rh双金属系统可用于合成异喹啉以及β-咔啉,呋喃[2.3- c ]吡啶,吡咯并[2,3- c ]吡啶和噻吩并[2,3- c ]吡啶衍生物。
Rhodium(III)-Catalyzed Synthesis of Isoquinolines from Aryl Ketone<i>O</i>-Acyloxime Derivatives and Internal Alkynes
作者:Pei Chui Too、Yi-Feng Wang、Shunsuke Chiba
DOI:10.1021/ol102504b
日期:2010.12.17
isoquinolines from aryl ketone O-acyloxime derivatives and internal alkynes has been developed using [Cp*RhCl2]2−NaOAc as the potential catalyst system. The present transformation is carried out by a redox-neutral sequence of C−H vinylation via ortho-rhodation and C−N bond formation of the putative vinyl rhodium intermediate on the oxime nitrogen, where the N−O bond of oxime derivatives could work as an internal
The reaction of oxime esters with a rhodium(I) precursor to form five-membered rhodacycles via N-O bond cleavage followed by C-H bond activation has been investigated by isolating these complexes. Kinetic studies on the formation of rhodacycles show that the reversible oxidative addition of the N-O bond in the oxime ester to RhCl(PPh3)(3) occurs at room temperature. The E-isomer of the oxime ester was found to undergo rhodacycle formation faster than the Z-isomer, which suggests that the geometry of the oxime esters reflects the geometry of intermediates during C-H activation. The rhodacycle reacted with an alkyne to construct an isoquinoline ring in both stoichiometric and catalytic conditions, despite its basic stability in air, in moisture, and even during heating, which demonstrates the potential of the rhodacycle as an intermediate for further catalytic transformation of oxime esters.