I'm not going to make statements about the (im)possibility of your proposed reactions, only about the HCN. A rather famous reaction involving HCN is the Gattermann formylation. If you use TFSE, you'll find several matches for Gattermann. I think that Gattermann used HCN in his original 1898 article, but afterwards, he and other chemists proposed safer ways of performing this type of reaction by generating HCN in situ. I often see that zinc cyanide is used for that purpose. So, for your own safety and convenience, I think you might consider in situ generation reactions.
Information on Gattermann's reaction is also available on Rh's site: https://www.thevespiary.org/rhodium/Rhodium/chemistry/formylation.gattermann.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/formylation.gattermann.html)
geh in die knie. wackle mit den hueften. klatsch in die haende. und tanz den mussolini.
Cyrax: please ask me about the refs one more time.. I told you I have NO refs, I came up with this synt on my own... is there any such thing as 3,4,5-triamino-toluene, or is it impossible to synthesize?
One more general point, just a moment ago i saw Assholiums synt on https://www.thevespiary.org/rhodium/Rhodium/chemistry/2cb.mannich.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/2cb.mannich.html)
where he is going via Mannich reaction, correct me if im wrong but I see no point in that... If he's going to use NaCN anyways, why not let it preform nuclephilic attack as i described, form nitrile and reduce it with Raney Ni or LAH as described in my original post in this thread ([7] -> [8] -> [9] -> [10]), wouldn't that be easier? I guess it depends, but just a thought...
Never underestimate the power of retrosynthesis.