The parent compound 5‐oxo‐10a‐phenyl‐2,3,10,10a‐tetrahydro‐5H‐[1,3]‐oxazolo‐[3,2‐b]‐isoquinoline‐10‐carboxylic acid ( 5 ) was prepared in large scale and a good yield by reaction between homophthalic anhydride ( 3 ) and 4,5‐dihydro‐2‐phenyl‐1,3‐oxazole ( 4 ). Thus, the closure of the isoquinoline ring and fusion of the 1,3‐oxazol ring occur in one step. Trans configuration was assumed for the product. The parent acid 5 was converted in four steps to the target aminomethyl derivatives 9a‐1 . The latter contain four features that make them interesting from pharmaceutical point of view.
