Grignard reactions were applied to synthesize 2-ethynyl-2-hydroxylallobetulin
5 from 2-oxoallobetulin 4. The compound plays an important role as starting material to
synthesize heterocyclic triterpenes using the click reaction. A series of new 1,2,3-triazole
derivatives derived from 2-oxoallobetulin were successfully obtained. Under similar reaction
conditions, only one compound 6 kept the hydroxyl functional group, while in the
other compounds 7, 8 and 9, water was eliminated. The structures of obtained compounds
were confirmed by 2D-NMR spectroscopy. The X-ray analysis of 5 indicated that only one
isomer was obtained and in this compound, the hydroxyl group is situated on the same side
as the ether group, the ethynyl group being situated at the opposite side. All products were
also evaluated for their cytostatic activity in cell culture including L1210, CEM and Hela.
Several compounds showed measurable cytostatic activity in the micromolar range.
Keywords: Grignard reactions, click reaction, 2-oxoallobetulin, 1, 2, 3-triazole, lymphoblast CEM tumor cells, cervix carcinoma HeLa,
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