Theoretical studies on relative stability of 3-acetyl pyrrolidine-2,4-dione and its N-acetyl derivative

In the present paper, Ab initio calculations have been performed for five t automers (a-e) of 3-acetyl pyrrolidine-2, 4-dione (1) and its N-acetyl deri vative (2) by using 6-31G and 6-31G** basis sets at Hartree-Fock level, ele ctronic correlation effects are also considered through MP2/6-31G** single- point energy calculations. The results obtained from HF/6-31G** and MP2/6-3 1G** calculations show that Id and 2a are the most stable tautomeric forms for compounds 1 and 2 respectively, which are in good agreement with the ex perimental results. The influences of N-acetyl substituent group on the rel ative stability of the tautomers are discussed.