Synthesis of the dopamine D2/D3 receptor agonist (+)-PHNO via supercritical fluid chromatography: preliminary PET imaging study with [3-11C]-(+)PHNO

•Improved synthesis of the dopamine agonist pharmaceutical (+)-PHNO.•First reported synthesis of key precursors for radiolabeling with [11C]CH3I.•Application of supercritical fluid chromatography to separate HNO enantiomers.•Modifications for consistent preparation of [3-11C]-(+)-PHNO.