Synthesis, Resolution, and Absolute Configuration of a Phosphine-Based Hemicryptophane Cage with an Endo Phosphorus...

The synthesis, characterization, and chiroptical properties of a new class of hemicryptophanes combining a phosphine moiety and a cyclotriveratrylene unit are reported. The synthesis was short and efficient. The racemic mixture of the cage was resolved by chiral high-performance liquid chromatography (HPLC), giving access to enantiopure molecular cages, whose absolute configurations could be assigned by electronic circular dichroism (ECD) spectroscopy. These new phosphines were then reacted with gold in order to make the corresponding enantiopure gold complexes. The X-ray structure reveals an endohedral functionalization of the cage with the gold metal entrapped in the heart of the cavity, leading to a V_bur of 58%. Moreover, the chirality of the cyclotriveratrylene unit was found to control the chiral arrangement of the aryl group linked to the phosphorus atom, located at the opposite side of the cavity.