If  I have 3o amine on a side chain, and I want to make it 2o amine by getting rid of -CH3, can I use BrCN and KOH ? Is this correct?

 

This is the "von Braun reaction". But this substitutes one alkyl to nitril. How do you know that methyl and not the R will be substitutet. The nitril has to be treated further. Nitril to Carbamidacid

this is the fluoxetine synthesis and the von Braun reaction at the last step. I wanted to know if I can use this method to other synthesis too

Probably.