(Solved): Not just carbon atoms can be chiral centers (a.k.a. stereocenters, or asymmet ...

???????

Not just carbon atoms can be chiral centers (a.k.a. stereocenters, or asymmetric centers). For example, tenofovir alafena mide has a chiral phosphorus atom! Assign \( R \) or \( S \) absolute configuration (based upon the C-I-P sequence rules) for the phosphorus stereocenter of tenofovir alafenamide (of the antiretroviral combination drug Biktarvy \( { }^{\mathrm{TM}} \) ): Bictegravir/emtricitabine/tenofovir alfenamide (Biktarvy \( { }^{\mathrm{m}} \) ) FDA Approved 2.7.2018. Fixed dose combination drug (50:200:25 \( \mathrm{mg} \) ) for treatment of HIV-1 infection in adults who have no antiretroviral treatment history or to replace current regimen. (Note: an \( s p^{2} \) hybridized oxygen atom is higher priority than Osp \( { }^{3} \) ) \[ \mathrm{P}=\quad(R \text { or } S)[\mathrm{A}] \]