So we form a carbonate intermediate molecule, the Thiamine Pyrophosphate carbonate. Now, as a result of the presence of the two electrons on this carbon atom, this becomes a good nuclear file. And that and now it acts as a strong nuclear file and attacks this electrophile. So this is one of the substrate molecules that we discussed in the previous lecture. So it's the ketosubstrate. In this particular case, we're using Zelulose phyphostate.