C–H Activation Induced by Oxidative Addition of N–O Bonds in Oxime Esters: Formation of Rhodacycles and Cycloaddition with Alkynes
作者:Takuya Shimbayashi、Kazuhiro Okamoto、Kouichi Ohe
DOI:10.1021/acs.organomet.6b00311
日期:2016.6.13
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.