[stevenAitsover]

http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv9p0242#Note3
For this first reaction once the nucleophile Flouride attack the Carbonyl of the aldehyde how does it connect to the nitro group. And what does IPA polar protic solvent have to do with this reaction?

[majorjp]

That reaction is actually a Henry Reaction, the F^- acts as a base that actually attacks the C adjacent to the nitro group. This create a nucleophilic nitroalkane which then reacts with the carbonyl C by nucleophilic attack. As for the IPA, I can only assume it acts as a H⁺ source.