Maslinic acid was obtained from olive-pressing residues, and several derivatives were formed. Rearrangements of 2-tosyloxy-derivatives of methyl maslinate made out by acetolysis. The main product of these rearrangements contained a cyclopentanic A-ring as a result of a concerted 2(3)-> 4-abeo rearrangement process. Moreover, when there was a ketone group at C-3 in the tosyloxy derivative, this concerted rearrangement did not occur, and only cyclohexanic compounds were formed. Experimental ¹³C NMR chemical shifts are given and a comparison with the theoretical ¹³C shifts (GIAO method with the MM+ geometries at the B3LYP/6-31G* level) showed good agreement between the two values.