An improved process for the synthesis of sufentanil with an overall yield of 26% is described. The reactive and high yielding N-debenzylation of the piperidine intermediate 7 using a mixture of Pd/C and Pd(OH)₂ was applied to other drug intermediates affording free amines in short reaction times. The deuterium-labeled sufentanil and the metabolite desmethylsufentanil were synthesized applying the optimized process.