A rhodium(III)-catalyzed cascade reaction of phthalic anhydrides with cyclic 2-diazo-1,3-diketones and methanol for modular access to esterified cyclohexenone-fused isocoumarins has been developed. This strategy involves the process of one C-C and two C-O bonds formation through C-H activation, transannulative coupling and subsequent annulation process. Furthermore, no additive and base are needed in this transformation, and interestingly, the reaction could proceed well under air atmosphere with broad substrate and good functional groups tolerance.
An efficient palladium-catalyzed ortho-aroylation of O-arylmethyl and aryl-substituted acetoxime ethers has been developed; this method has high mono-site selectivity and does not require exogenous ligands. Under the direction of a simple exo-acetoxime auxiliary, a broad scope of masked arylmethyl alcohols and phenols as well as various aromatic aldehydes are compatible with this transformation, which probably follows a mechanistic pathway involving a six- or five-membered exo-cyclopalladated intermediate. The strategy can be expediently adopted to prepare synthetically valuable 1H-benzo[d][1,2]oxazines and benzo[d]isoxazoles. The directing group can be easily removed from the products to afford the functionalized diaryl ketones.
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