Design a four step synthesis of the target shown from the reagents listed. Give only the letters of each step. Assumer appropriate workup.
Solution: We are starting with a benzene ring that has a tertbutyl group. The product has CN group para (opposite) to the tertbutyl group. How do we put CN group on the benzene ring? It must go through the diazonium ion. We first add NO2, turn NO2 into NH2, turn NH2 into N2+ and turn N2+ into CN. Notice that an alkyl group is an ortho/para direction and since CN is para to the tertbytul it is in the right right position.
Now, let's go through the reagents.
Add NO2 to the benzene ring: HNO3, H2SO4 D
Turn NO2 into NH2: H2, Pd-C, E
Turn NH2 into N2+: NaNO2, HCl A
Turn N2+ into CN: CuCN C