The synthesis of granisetron has been reported: The reaction of 1-methylindazole-3-carboxylic acid (I) with oxalyl chloride and DMF in dichloromethane gives 1-methylindazole-3-carbonyl chloride (II), which is then condensed with endo-9-methyl-9-azabicyclo[3.3.1]nonan-3-amine (III) by means of triethylamine in dichloromethane.
A synthesis of [11C]-granisetron has been published: The desmethylation of granisetron (I) with vinyl chloroformate in refluxing dichloroethane gives the intermediate vinyl ester (II), which is decarboxylated with dry HCl in dichloromethane yielding the desmethylgranisetron (III). Finally, this compound is methylated with [11C]-methyl iodide and NaOH in DMF at 145 C.