| Abstrakt: |
Regioselective acylation of four polyhydroxylated natural compounds, deacetyl asperulosidic acid (1), asperulosidic acid (2), puerarin (3) and resveratrol (4) by Candida antarctica Lipase B in the presence of various acyl donors (vinyl acetate, vinyl decanoate or vinyl cinnamoate) was studied. Compounds 1, 2 and 4 were regioselectively acetylated with vinyl acetate to afford products, 3'- O -acetyl-10- O -deacetylasperulosidic acid (1a), 3',6'- O -diacetyl-10- O -deacetylasperulosidic acid (1b), 3'- O -acetylasperulosidic acid (2a), 3',6'- O -diacetylasperulosidic acid (2b), 4'- O -acetylresveratrol (4a), respectively, with yields of 22 to 50%, while reactions with vinyl decanoate and vinyl cinnamoate were slow with lower yields. Compound 3 was readily acylated with all three acyl donors and quantitatively converted to products 6?- O -acetylpuerarin (3a), 6?- O -decanoylpuerarin (3b), 6?- O -cinnamoylpuerarin (3c), respectively. The structures of these acylated products were determined by spectroscopic methods (MS and NMR). [ABSTRACT FROM AUTHOR] |
