I assume you mean going from aniline (aminobenzene) to benzamide (benzoylamide). The easiest way I can see is to transform it back into benzene and go from there.
(Keep in mind though that this is highly theoretical; some of these reactions are rather dangerous, particularly the arenediazonium salt in step 2, and the acyl chloride in step 4.)
- Reaction with sodium nitrite in cold acid generates the arenediazonium salt,
#"C"_6"H"_6"N"_2"Cl"#. These should be treated as temporary intermediates used in further reactions, because they may explode on you.
- Hypophosphorous acid reduces the arenediazonium salt all the way down to benzene.
- A Friedel-Crafts Acylation with phosgene gives benzoyl chloride. Obviously, this should be done with a high level of safety equipment.
- A violent reaction with ammonia generates the final product, benzamide.