1069115-13-4Relevant academic research and scientific papers
Synthesis of Amides and Esters by Palladium(0)-Catalyzed Carbonylative C(sp3)?H Activation
?arny, Tomá?,Baudoin, Olivier,Clemenceau, Antonin,Rocaboy, Ronan
supporting information, p. 18980 - 18984 (2020/09/01)
The 1,4-palladium shift strategy allows the functionalization of remote C?H bonds that are difficult to reach directly. Reported here is a domino reaction proceeding by C(sp3)?H activation, 1,4-palladium shift, and amino- or alkoxycarbonylation, which generates a variety of amides and esters bearing a quaternary β-carbon atom. Mechanistic studies showed that the aminocarbonylation of the σ-alkylpalladium intermediate arising from the palladium shift is fast using PPh3 as the ligand, and leads to the amide rather than the previously reported indanone product.
Synthesis of benzocyclobutenes by palladium-catalyzed C-H activation of methyl groups: Method and mechanistic study
Chaumontet, Manon,Piccardi, Riccardo,Audic, Nicolas,Hitce, Julien,Peglion, Jean-Louis,Clot, Eric,Baudoin, Olivier
supporting information; experimental part, p. 15157 - 15166 (2009/03/12)
An efficient catalytic system has been developed for the synthesis of benzocyclobutenes by C-H activation of methyl groups. The optimal conditions employed a combination of Pd(OAc)2 and PtBu3 as catalyst, K2CO3 as the base, and DMF as solvent. A variety of substituted BCB were obtained under these conditions with yields in the 44-92% range, including molecules that are hardly accessible by other methods. The reaction was found limited to substrates bearing a quaternary benzylic carbon, but benzocyclobutenes bearing a tertiary benzylic carbon could be obtained indirectly from diesters by decarboxylation. Reaction substrates bearing a small substituent para to bromine gave an unexpected regioisomer that likely arose from a 1,4-palladium migration process. The formation of this "abnormal" regioisomer could be suppressed by introducing a larger subsituent para to bromine. DFT(B3PW91) calculations on the reaction of 2-bromo-tert-butylbenzene with Pd(PtBu3) with different bases (acetate, bicarbonate, carbonate) showed the critical influence of the coordination mode of the base to induce both an easy C-H activation and to allow for a pathway for 1,4-palladium migration. Carbonate is shown to be more efficient than the two other bases because it can abstract the proton easily and at the same time maintain κ1-coordination without extensive electronic reorganization.
