Semisynthesis of Derivatives of Oleanolic Acid from Syzygium aromaticum and Their Antinociceptive and Anti-Inflammatory Properties

Table 1

Interpretation of FT-IR spectrum of oleanane-derived compounds.

Compounds	Absorption bands
	1	3406	2935, 2864	1688	1460	1034
2	3205	2969–2853	1723, 1680	1457	1008
5	3204	2970, 2945	1771, 1723	1455	1010
3	—	2972, 2966	1724	1470	1020
6	—	2940, 2860	1688	1461	1030
4	3346	2940	1726–1710	1462	1031

C₃, in ring A of the chemical structure of OA, was successfully acetylated. In addition, the methylation of C₂₈, ring E of an acetyl-derivative of OA compound, led to formation of ester derivatives: compounds 3 and 6. Compound 4 is 28-methyloleanane derived directly from OA by treating OA with iodomethane after which K₂CO₃ was added to stabilize the pH. FT-IR shows carbonyl shift compared to that of OA; this confirms the formation of a methyl ester in the place of carboxylic acid.