[Parathormon]

Good Evening ,


I am working on some structure which contains bridged alkyl group (norbornane) - i need to attach phenyl group to one of the secondary carbons;

Molecule is quite complex and multi-step to build - its some novel PDE5 inhibitor, thats why better to use excess of phenyl-substrate;

After some consideration We are about to choose Negishi coupling or Kumada with excess of respectively phenylzinc iodide or phenylmagnesium iodide;

Convert our alkyl to iodide first and then couple with one of above methods;

The Problem is here how does theese coupling „work” in case of our alkyl halide is exo isomer which is our goal isomer - does theese methods do retention, inversion or racemize this configuration?

there is also possible to use chiral catalyst to enrich the product with desired isomer i guess but the most optimal would be to keep retention somehow because our substrate is actually chiral.