Highly efficient transmetalation between gold phosphites and iodopalladium species is presented. In addition to successful transfer of cyclic and acyclic phosphites, studies involving P‐chiral substrates revealed that an initial protodeauration as well as the target transmetalation were both stereospecific, and that the overall process occurred with retention of configuration at phosphorus. Building on the mechanistic work, a catalytic approach to the synthesis of chiral P‐arylated nucleoside derivatives was developed. This chemistry has the potential to be easily adapted for the preparation of a diverse group of P‐chiral species.

The synthesis of P-arylated spirocyclic bisphosphonates is described. The title compounds were generated through a process that combined transesterification with a palladium catalyzed P-arylation. The cross-coupling step could be carried out at room temperature using aryl iodides, while analogous reactions involving aryl bromides required heating. Nitrogen, oxygen, and sulfur containing heterocycles were also success-fully incorporated into the framework. Using this approach 20 new arylated compounds were generated bearing a range of electrophiles and functional groups. For the more reactive aryl iodides, the catalyst loading could be decreased to 0.3 % Pd per PÀH group in scaled-up versions of the method. The two-step process does not require the use of chlorophosphorus reagents.

Transesterification of pentaerythritol (I) is followed by cross‐coupling in the presence of aryl iodides or bromides under conditions B) or C).

The synthesis of resolved P-metalated nucleoside phosphoramidites is described. These rare compounds were initially prepared with gold as the metal center; however, the gold can be removed using basic phosphines or solid-supported triphenylphosphine. Treatment of the free nucleoside phosphoramidite with a platinum source generated a unique platinated dinucleoside species with a diastereomeric ratio of >99:1.

The Front Cover shows the generation and reactivity of configurationally stable P‐metallated nucleoside derivatives. The examples shown in this illustration were prepared through a series of stereospecific protodemetalation and transmetalation reactions. The aurated examples were successfully used as substrates in stereospecific base‐free P‐arylation reactions leading to functionalized nucleosides. The authors thank Barbara Stockland for the design of the cover. More information can be found in the https://doi.org/10.1002/ejoc.201800397