摘要:
The preparation of Elanco Animal Health immunopotentiator (S)-ethyl-1-(2-thiopheneacetyl)-3-piperidinecarboxylate (1) is described. The synthesis includes a new resolution of racemic ethyl nipecotate with dibenzoyl-L-tartaric acid. The resolved salt is found to couple directly with commercially available 2-thiopheneacetyl chloride under environmentally friendly Schotten-Baumann conditions to afford the amide in high yield. The final product is an oil which is purified by wiped film evaporative distillation.