A practical synthesis of the kappa opioid receptor selective agonist (+)-5R,7S,8S-N-methyl-N-[7-(1-pyrrolidinyl)-1-oxospiro[4,5]dec-8-yl]benz eneacetamide (U69,593)
A novel approach to the synthesis of the kappa opioid receptor agonist U69,593 has been developed. This approach improves upon current literature methods by substituting stable and isolable cyclic sulfates for the unstable epoxides. The new approach provides access to gram quantities of the target compound and displays excellent control of the relative stereochemistry. The absolute stereochemistry as well as biological activity of the U69,593 produced by this new method was verified using X-ray crystal structure analysis and binding assays for the kappa opioid receptor.