<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>1, 3‐Dipolar cycloaddition of 2‐arylmethylidenepyranothiazolopyrimidones (III) to an azomethine ylide, generated by a decarboxylative route from sarcosine (VI) and acenaphthenequinone (V), affords the novel spiro‐compounds (VII) in moderate yields.</p> </abstract>