C(sp2)–H bond oxidation of oximes or azobenzenes with diverse carboxylic acids has been developed. In contrast to the previous catalytic systems, this protocol features mild conditions (close to room temperature for most cases) and a broad substrate scope (up to 64 examples), thus constituting a versatile method to directly prepare diverse O-aryl esters. Moreover, the superiority of the nitrate additive
Rhodium(III)-catalyzed [3+2] annulative coupling between oximes and electron-deficient alkynes
作者:Xukai Zhou、Songjie Yu、Zisong Qi、Xingwei Li
DOI:10.1007/s11426-015-5408-8
日期:2015.8
Rhodium(III)-catalyzedcoupling between ketoximes and alkynes via C-H activation and annulation typically followed the [4+2] selectivity to afford isoquinolines. By designing alkynes bearing a highly electron-withdrawing group and under substrate control, we have successfully switched the selectivity of the coupling between oximes and alkynes to the alternative [3+2] annulation, leading to the efficient
A Rh-catalyzed intermolecular coupling of diazomalonates with arene C-H bonds is reported. The reaction is initiated by electrophilic C-H activation, which is followed by coupling of the arylrhodium(III) complex with the diazomalonate. In most cases, arenes with oximes, carboxylic acids, and amines as directing groups cross-couple with diazomalonates with excellent regioselectivities and functional
corresponding products in moderate to good yields. Various aryl ketoximes substituted with electron‐withdrawing functional groups are all well tolerated. A preliminary mechanistic study revealed that potassium acetate is essential for the intermolecular amination.
Pd-Catalyzed <i>Ortho</i>-C−H Acylation/Cross Coupling of Aryl Ketone <i>O</i>-Methyl Oximes with Aldehydes Using <i>tert</i>-Butyl Hydroperoxide as Oxidant
作者:Chun-Wo Chan、Zhongyuan Zhou、Albert S. C. Chan、Wing-Yiu Yu
DOI:10.1021/ol101618u
日期:2010.9.3
Pd-catalyzed protocol for direct C−H bond acylation by cross coupling of aryl ketone oximes and aldehydes using tert-butyl hydroperoxide (TBHP) as oxidant was developed. With oximes as a directing group for the C−H activation, the coupling with aldehydes was achieved with remarkable regioselectivity. The acylationreactions exhibit excellent functional group tolerance, and both aliphatic and heteroaromatic