The first step is a nucleophilic conjugate addition of the amine with the enol to the amine ketone 3 in a reversible reaction. This intermediate then fragments to the imine 4a and the saturated cyclohexanone 4b in a non-reversible reaction and both fragments recombine in a condensation reaction to the conjugated imine 5.
The initial step involves the amine reacting with the enol of ketone 3 in a reversible process. This intermediate then breaks down into imine 4a and saturated cyclohexanone 4b in a non-reversible reaction, and these fragments combine through condensation to form conjugated imine 5.