Phenylcyclohexylamines are tertiary amines, therefore you cannot make them through reductive amination, as that reaction implies that you have a carbonyl compund to which you reductively add an amine. A carbonyl (double-bonded oxygen) on that center carbon would somehow require it to have five bonds (one to the benzene ring, two to the cyclohexane, and two to an oxygen), which it can not have, only four.