Rhodium catalyzed hydroformylation of kaurane derivatives: A route to new diterpenes with potential bioactivity

Ent-kaurane derivatives from the root cortex of yacon and other three Smallanthus species (Heliantheae, Asteraceae)

“…The isolated compounds were identified by their 1 H NMR and 13 C NMR spectra and comparison with data reported in the literature (Piozzi et al, 1971;Calle et al, 1988;Bohlmann et al, 1979Bohlmann et al, , 1980aKakuta et al, 1992;Peixoto et al, 2008). NMR measurements were recorded on a Bruker AC 200 operating at 200 MHz for 1 H and at 50 MHz for 13 C using 5 mm sample tubes and deuterated chloroform as solvent.…”

Preparation of Antiproliferative Terpene-Alkaloid Hybrids by Free Radical-Mediated Modification of ent-Kauranic Derivatives

“…ent-kaurenoic acid 1 has also been extensively involved in SAR studies and chemical modification was reported frequently at the level of the carboxylic functional group. The reactivity of the exo-methylenic ∆ 16 -double bond was mostly addressed via the heteroatom addition processes or trivial oxidative transformations and only scarce data involve deeper skeletal modifications based on this functionality [8,9]. The exo-methylene moiety of acid 1 represents an additional opportunity for increasing molecular complexity based upon Ent-kaurenoic acid 1 has also been extensively involved in SAR studies and chemical modification was reported frequently at the level of the carboxylic functional group.…”

In vitro antimicrobial activity of two dibutyltin(IV) complexes of kaurenic acids derivatives

“…Different investigators have produced an important number of derivatives by hemi-synthesis, for instance, derivatization of the acid group on carbon-19 to obtain alcohols, esters and amides (Diamantino et al, 2008;Mthembu et al, 2010;Haraguchi et al, 2011). However, derivatives have also been obtained by funtionalization of the exocyclic and endocyclic double bonds in grandiflorenic acid (Peixoto et al, 2008;HuesoFalcón et al, 2010;Hueso-Falcón et al, 2011).…”

“…[1] and grandiflorenic acid (ent-kaur-9(11), 16-dien-19-oic) [2], are ent-kaurane diterpenes amply distributed in the vegetal kingdom (Peixoto et al, 2008;Boeck et al, 2005;Vieira et al, 2002;Otto and Simoneit, 2001). Both are natural products common in frailejones species (Espeletiinae, Asteraceae).…”