106818-49-9Relevant articles and documents
Fluorinated Kaurenoids. Part 2. Preparation of Methyl ent-17,17,17-Trifluorokaur-15-en-19-oate and ent-16,16-Difluoro-17-norkauran-19-oic Acid from Xylopic Acid
Cross, Brian E.,Erasmuson, Anton,Filippone, Paolino
, p. 1293 - 1297 (1981)
An attempt to convert methyl ent-16-oxo-17-norkauran-19-oate (3), derived from xylopic acid, into methyl ent-17,17-difluorokaur-16-en-19-oate failed.However, treatment of the norketone (3) with diethylaminosulphurtrifluoride (DAST) gave methyl ent-16,16-difluoro-17-norkauran-19-oate (5).The latter afforded the corresponding acid (4) which was active as a growth promoter in a dwarf-rice bioassay.Treatment of methyl deacetylxylopate (18) with DAST, followed by cleavage of the terminal methylene group, yielded methyl ent-15-fluoro-16-oxo-17-norkauran-19-oate (15), which on reaction with dibromodifluoromethane and tris(dimethylamino)phosphine gave, not the expected 17,17-difluoro-olefin (19), but methyl ent-17,17,17-frifluorokaur-15-en-19-oate (28) in poor yield.Reduction of methyl xylopate with di-imide gave the 16β-methyl compound (24) stereospecifically.The latter was readily converted into methyl 15-oxokauranoate (26), but steric hindrance prevented the reaction of the oxo-group with DAST to give the 15,15-difluoride, under normal reaction conditions; using a much longer reaction time a trace of the gem-difluoride was formed.During reduction of the dithiocarbonate (27) of methyl deacetylxylopate with tri-n-butyltin hydride into the isomeric methyl kaurenoates (8) and (31), the 17-thiol ester (32) was also formed by a sigmatropic rearrangement.
Synthesis, cytotoxicity and antiplasmodial activity of novel ent-kaurane derivatives
Batista, Ronan,Garcia, Pablo A.,Castro, Maria Angeles,Miguel Del Corral, Jose M.,Speziali, Nivaldo L.,De P. Varotti, Fernando,De Paula, Renata C.,Garcia-Fernandez, Luis F.,Francesch, Andres,San Feliciano, Arturo,De Oliveira, Alaide B.
, p. 168 - 176 (2013/05/09)
This paper reports on the syntheses and spectrometric characterisation of eleven novel ent-kaurane diterpenoids, including a complete set of 1H, 13C NMR and crystallographic data for two novel ent-kaurane diepoxides. Moreover, the antineoplastic cytotoxicity for kaurenoic acid and the majority of ent-kaurane derivatives were assessed in vitro against a panel of fourteen cancer cell lines, of which allylic alcohols were shown to be the most active compounds. The good in vitro antimalarial activity and the higher selectivity index values observed for some ent-kaurane epoxides against the chloroquine-resistant W2 clone of Plasmodium falciparum indicate that this class of natural products may provide new hits for the development of antimalarial drugs.
Fluorination of kaurenoic acid derivatives by remote functionalization
Anaya, Josefa,Grande, Ma Concepción,Grande, Manuel,Patino, Ana-Isabel,Torres, Pascual
, p. 1429 - 1431 (2007/10/03)
Kauranoids and related tetracyclic diterpenoids have recently shown an increasing interest because of the discovery of new biological activities that can be modified by the introduction of a fluorine atom. In this article it is described the stereospecific fluorination of the kauranols 6 and 7 by remote functionalization at the 'unactivated' C-7 position.
