The scientific interest in diterpenic tetracyclic ent-kaur-16-en-19-oic (1) is explained by
the fact that this compound possesses a broad spectrum of biological activities [1-3]. It was
isolated from different vegetal sources, especially from sunflower Helianthus sp. [4].
Polyfunctionalized tetracyclic ent-kaurenic terpenoids are also of a great interest, as a
result of their pronounced biological activity. For the functionalization of ent-kaur-16-en-19-oic
acid (1) the Prevost – Woodward method was used.
Herein, we present the results of the transformation of ent-kaur-16-en-19-oic acid (1) by
reaction with PhI(OAc)2/LiBr, using the method described in the literature [5].
As a result, a mixture of diterpenic compounds was obtained, which was purified by
column chromatography, resulting in the isolation of the functionalized ent-kaurenic diterpenoids
(2) – (4). Their structures were elucidated by 1H, 13C NMR, IR and MS spectroscopies data. It
should be mentioned, that diterpenoids (2) - (3) containing a bromine atom at C-17 can
potentially be endowed with interesting biological properties.

As a result of Prevost–Woodward reaction of ent-kaur-16-en-19-oic acid (1), new
derivatives of ent-kaurenic acid, functionalized at C-15, C-16 and C-17 carbon atoms, have been
obtained.
References:
1. Na, M. K.; Oh, W, K.; Kim, Y. H.; Cai, X. F.; Kim, S. H.; Kim, B. Y.; Ahn, J. S. Bioorg. Med.
Chem. Lett., 2006, 16, 3061–3064.
2. Dang, N. H.; Zhang, X. F.; Zheng, M. S.; Son, K. H.; Chang, N. W.; Kim, H. P.; Bae, K. H.;
Kang, S. S. Arch. Pharm. Res., 2005, 28, 28-33.
3. Jung, H. A.; Lee, E. J.; Kim, J. S.; Kang, S. S.; Lee, J.-H.; Min, B.-S.; Choi, J. S. Arch. Pharm.
Res., 2009, 32, 1399-1408.
4. Ungur, N.; Grinco, M.; Kulciţki, V.; Barba, A.; Bîzîcci, T.; Vlad, P. F. Chem. J. Mold. 2008, 4
(2), 106-109.
5. Emmanuvel, L.; Ali Shaikh, T. M.; Sudalai, A. Org. Lett., 2005, 7 (22), 5071-5074.