Pd-Catalyzed/Iodide-Promoted α‑Arylation of Ketones for the Regioselective Synthesis of Isocoumarins

A variety of isocoumarins have been synthesized directly from 2-halobenzoates and ketones through a palladium-catalyzed α-arylation step followed by an intramolecular cyclization process. The addition of iodide anions to the reaction mixture increased yields and selectivities especially when 2-bromobenzoates were employed. This phosphine-free one-pot synthesis features a high functional group tolerance and gives access to richly decorated isocoumarins. This general methodology was successful in the total synthesis of Xyridin A, an important natural product with antibacterial and antifungal activity

A Sequential Pd/Norbornene-Catalyzed Process Generates <i>o-</i>Biaryl Carbaldehydes or Ketones via a Redox Reaction or 6<i>H</i>‑Dibenzopyrans by C–O Ring Closure

<i>o</i>-Biaryl carbaldeydes and ketones are obtained through the one-pot reaction of <i>o</i>-aryl iodides with <i>o</i>-bromobenzyl alcohols under the catalytic action of Pd and norbornene, in the presence of a base. The same reaction can also give dibenzopyrans by Pd and norbornene catalysis with a different termination, leading to C–O ring closure. In both cases the process first leads to a five-membered palladacycle, which controls C–C coupling, then to a seven-membered oxapalladacycle, which gives aldehydes and ketones or dibenzopyrans