A diastereoselective synthesis of Cebranopadol, a novel analgesic showing NOP/mu mixed agonism

A diastereoselective synthesis of the title compound as a single E diastereomer has been efficiently accomplished by assembling the featured pyrano-indole scaffold of the spiro[cyclohexanedihydropyrano[ 3,4-b]-indole]-amine framework through an oxa-Pictet-Spengler reaction, promoted by a cheap and green Zeolite catalyst. Basic pharmacological experiments demonstrate that Cebranopadol acts as a mixed nociception/orphanin FQ (NOP) and mu (MOP) opioid receptor agonist useful for treatment of chronic pain.