Synthesis and cytotoxicity of 28-carboxymethoxy lupane triterpenoids. Preference of 28- O-acylation over 28- O-alkylation of betulin by ethyl bromoacetate

28-Carboxymethoxy lupane tritepenoids 3 and 4 were synthesized by alkylation of betulin with the THP protected 2-hydroxyethyl iodide followed by oxidation and reduction. Direct reaction of betulin ( 5) or betulone ( 10) with ethyl bromoacetate led to 28- O-acylation, instead of 28- O-alkylation. The...

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Bibliographic Details
Published in:Chinese chemical letters 2009-10, Vol.20 (10), p.1141-1144
Main Authors: Aye Mar, Aye, Koohang, Ali, Majewski, Nathan D., Szotek, Erika L., Eiznhamer, David A., Flavin, Michael T., Xu, Ze Qi
Format: Article
Language:English
Subjects:
28- O-acylation
28- O-alkylation
Betulin
Betulinic acid
Betulonic acid
Cytotoxicity
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Summary:28-Carboxymethoxy lupane tritepenoids 3 and 4 were synthesized by alkylation of betulin with the THP protected 2-hydroxyethyl iodide followed by oxidation and reduction. Direct reaction of betulin ( 5) or betulone ( 10) with ethyl bromoacetate led to 28- O-acylation, instead of 28- O-alkylation. The targeted compounds 3 and 4 were not cytotoxic at the highest concentration tested (75 μmol/L), suggesting that elongation of the chain length at the 28-position in both betulinic acid ( 1) and betulonic acid ( 2) was detrimental to the cytotoxicity. The acylation products 28- O-bromoacetates ( 8a, 8b and 11) and 28- O-methoxyacetate 13 exhibited cytotoxicity against several cancer cell lines tested.
ISSN:1001-8417
1878-5964
DOI:10.1016/j.cclet.2009.04.001