27570-20-3Relevant articles and documents
Synthesis and anticancer activity of novel betulinic acid and betulin derivatives
Kommera, Harish,Kaluderovic, Goran N.,Kalbitz, Jutta,Paschke, Reinhard
scheme or table, p. 449 - 457 (2011/04/16)
A series of novel betulinic acid derivatives 3-11 and betulin derivatives 12-17 were synthesized. The compounds were characterized by the means of 1H- and 13C-NMR spectroscopy as well as mass spectrometry. The compounds have been tested on ten tumor cell lines of different histogenic origin. The most active derivatives, containing a chloroacetyl group on C-3 in betulinic acid 9 and C-28 in betulin 15, were up to ten times more cytotoxic and many fold more selective towards tumor cells in comparison to normal cells (fibroblasts) than betulinic acid. Furthermore, compound 15 was found to possess cell growth inhibition even when treated for a short time on anaplastic thyroid cancer cells (SW1736).
Assessment of antimycobacterial activity of a series of mainly marine derived natural products
Koenig, Gabriele M.,Wright, Anthony D.,Franzblau, Scott G.
, p. 337 - 342 (2007/10/03)
A series of mainly marine derived natural products were tested for their activities against Mycobacterium tuberculosis and M. avium. Of the thirty- nine compounds tested fifteen demonstrated minimum inhibition concentrations (MICs) of 32 μg/ml or less, and eleven had MICs of 16 μg/ml or less. The most active compound found in this study was the sponge derived metabolite axisonitrile-3 (MIC 2 μg/ml).
Simple synthesis of allobetulin, 28-oxyallobetulin and related biomarkers from betulin and betulinic acid catalysed by solid acids
Li, Tong-Shuang,Wang, Jian-Xin,Zheng, Xue-Jing
, p. 3957 - 3965 (2007/10/03)
Allobetulin (3a) and allobetulin acetate (3b) were efficiently prepared in excellent yield from betulin (2a) and betulin 3-acetate (2b) catalysed by a number of solid acids in refluxing dichloromethane. Sulfuric acid on silica, montmorillonite clays (both K10 and KSF), kaolinite, bleaching clay and toluene-p-sulfonic acid on silica are efficient catalysts for these conversions. Similarly, 28-oxyallobetulin (3c) and 28-oxyallobetulin acetate (3d) were obtained in good and excellent yield from betulinic acid (2c) and betulinic acid acetate (2d) respectively catalysed by montmorillonite K10. Two allobetulin related biomarkers, 19β,28-epoxy-A-neo-18α-olean-3(5)-ene (4a) and A-neo-18α-olean-3(5)-en-28→19β-olide (4b) were synthesised either from 3a and 3c or directly from 2a and 2c in refluxing benzene or cyclohexane catalysed by montmorillonite K10. Two other biomarkers, 19β,28-epoxy-18α-olean-2-ene (10a) and 18α-olean-2-en-28→19β-olide (10b) were also synthesised based on the above transformations. The direct formation of allobetulane related biomarkers from natural betulin 2a and betulinic acid 2c catalysed by clay mineral (montmorillonite) is of great geochemical interest.
A reagent for selective deprotection of alkyl acetates
Xu, Yao-Chang,Bizuneh, Amsalu,Walker, Clint
, p. 9086 - 9089 (2007/10/03)
The use of magnesium methoxide for selective deprotection of alkyl esters is described. By adjusting the equivalents of the magnesium methoxide reagent, it is possible to selectively cleave primary acetate in the presence of secondary and tertiary acetate and to cleave secondary acetate in the presence of tertiary acetate. A high selectivity can also be obtained for the same primary acetates if the β-positions of the acetates render a different steric bulkiness. This mild reagent has been successfully applied to the selective deprotection of many natural-occurring molecules including hydroxycitronnellol diacetate, trans-sobrerol diacetate, betulin diacetate, and baccatin III.