3-hydroxypyridones 8/9 (azagrevellins) were prepared by reaction of the pyrrolidinetrione 4 and diazoalkanes. The ring enlargement proceeded by anionotropic [1,2]-rearrangement introducing carbon between C-3 and C-4 or, to a lesser extent, between C-2 and C-3 due to the different migration aptitudes of the two acyl groups involved. In a cognate manner ring expansion between C-2 and C-3 occured by the interaction of