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Abstract: Regioselective Michael addition of purine derivatives to α,β-unsaturated carbonyl compounds could be catalyzed by d-aminoacylase amano (DA) in DMSO. The influence of reaction conditions on the Michael addition, including solvent, temperature, and enzyme concentration was systematically investigated. Then we extended this methodology to six structurally diverse purine derivatives and a variety of α,β-unsaturated carbonyl compounds. 21 Michael adducts were selectively synthesized in moderate to high yields. It is the first report on enzyme-catalyzed Michael addition for the preparation of purine derivatives. [Copyright &y& Elsevier]

Abstract: A fast and green protocol for the Michael addition of N-heterocycles to α,β-unsaturated compounds at room temperature was developed using a basic ionic liquid, 1-methyl-3-butylimidazolium hydroxide, [bmIm]OH, as a catalyst and a reaction medium. The reactions were performed at room temperature with good yields in short reaction times (0.5–3h). This strategy is quite general and it works with a broad range of N-heterocycles, including five-membered N-heterocycles, pyrimidines and purines. The recovered ionic liquid could be reused for several cycles with consistent activity. [Copyright &y& Elsevier]

Abstract: A new strategy for the enzymatic synthesis of pyrimidine derivatives containing a sugar branch was developed via combining of Michael addition and acylation. The first-step reaction of pyrimidines and vinyl 3-propionyloxy propionate was catalyzed by Amano lipase M from Mucor javanicus in DMSO. The initial reaction rates of different pyrimidines decreased in the order of fluorouracil, uracil, thymine, in agreement with their nucleophilicity. The succeeding regioselective acylation of d-glucose and d-mannose with the Michael adducts was catalyzed by alkaline protease from Bacillus subtilis in pyridine. The d-glucose and d-mannose were all acylated at C-6 position. Moderate yield was obtained for each step. [Copyright &y& Elsevier]