ORGN 391 |
| Regioselective acylation of 1-b-D-arabinofuranosylcytosine (ara-C) using vinyl benzoate (VB) as an acyl donor and Novozym 435 as a catalyst was carried out in various reaction media including pure organic solvents, organic solvent mixtures and ionic liquid (IL)-containing systems for the first time. Although the reaction was highly regioselective in all the media assayed, a remarkable enhancement of substrate conversion (from below 6.1% to 99.4%) was achieved with a co-solvent mixture of 1-butyl-3-methylimidazolium hexafluorophosphate (C4MIm•PF6) and pyridine compared with other media tested. The optimum molar ratio of VB to ara-C, initial water activity, temperature and shaking rate were 25:1, 0.11, 40 ˚C and 250 rpm, respectively. Under the optimum reaction conditions mentioned above, the initial rate, substrate conversion and the regioselectivity were 0.49 mM•min-1, 99.4% and 99%, respectively. The product of the lipase-catalyzed reaction was characterized by 13C NMR and was shown to be 5 ¢-O-benzoyl ara-C. |
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New Reactions and Methodology, Total Synthesis, Materials, Devices and Switches, Lipids, Nucleotides and Mimetics
8:00 PM-10:00 PM, Tuesday, March 27, 2007 Hyatt Regency Chicago -- Riverside Center, Poster
Division of Organic Chemistry |