Ruthenium(IV) complexes were identified as key intermediates of C−H/O−H activations by weak O‐coordination. Thus, the annulations of sulfoxonium ylides by benzoic acids provided expedient access to diversely‐decorated isocoumarins with ample scope. Detailed experimental and computational studies provided strong support for a facile BIES‐C−Hactivation, along with cyclometalated ruthenium(IV) intermediates
Synthesis of 4-Alkylated Isocoumarins via Pd-Catalyzed α-Arylation Reaction
作者:Shane Plunkett、Lindsey G. DeRatt、Scott D. Kuduk、Jaume Balsells
DOI:10.1021/acs.orglett.0c02851
日期:2020.10.2
method for the rapid preparation of substituted isocoumarins is reported. The transformation takes advantage of a spontaneous intramolecular cyclization that follows the Pd-catalyzed α-arylation of aldehydes with 2-halobenzoic esters. The reaction uses an air-stable, single-component palladium catalyst and provides access to 4-alkylated isocoumarins in one step from commercial starting materials. The
for the preparation of 3-substituted isocoumarins via palladium-catalyzed nucleophilic addition/oxidative annulation of bromoalkynes with benzoic acids has been developed. Remarkably, preliminary mechanistic studies indicated that the transformation might proceed via a stereo- and regioselective nucleophilic addition and C–H functionalization procedure.
The Rh(III)-catalyzed C–H activation initiated cyclization of benzoicacids with electron-rich geminal-substituted vinyl acetates was described. The reaction was employed to prepare a range of 3-aryl and 3-alkyl substituted isocoumarins selectively.
Sulfoxonium Ylides as Carbene Precursors: Rhodium(III)‐Catalyzed Sequential C−H Functionalization, Selective Enol Oxygen‐Atom Nucleophilic Addition, and Hydrolysis
作者:Yuanqiong Huang、Xueli Lyu、Hongjian Song、Qingmin Wang
DOI:10.1002/adsc.201900861
日期:2019.11.19
Herein, we report a protocol for Rh(III)‐catalyzed annulation reactions between oxazolines and sulfoxonium ylides via a sequence involving C−H activation, selective enol oxygen‐atom nucleophilic addition, and hydrolysis. This practical, operationally simple protocol has a wide substrate range, excellent regioselectivity, and moderate to good yields.