棉子糖乙烯酯的酶催化选择性合成研究

Enzyme-catalyzed Regioselective Synthesis of Novel Raffinose Vinyl Esters

研究了无水吡啶中酶催化棉子糖和丁二酸二乙烯酯、己二酸二乙烯酯、癸二酸二乙烯酯的酯交换反应 ,高选择性地合成了 3种具有不同链长的可聚合的棉子糖乙烯酯 .化合物经 1H NMR,13 C NMR和 2 DNMR表征 ,确证主要在棉子糖的β-呋喃果糖残基的 C-1位 OH上酯化 .考察了 7种不同来源的酶催化棉子糖酯合成的活性及温度、时间对反应的影响 .

Sugar esters have recently received increased attention from the viewpoint of renewable resources. Specifically vinyl esters from carbohydrates by enzyme-catalyzed regioselective transformations offer a new family of functional water-soluble monomers for preparation of sugar-based polymers. Here we reported enzyme-catalyzed regioselective synthesis of novel polymerizable raffinose vinyl ester. Transesterification of raffinose with divinyl succinate, divinyl adipate and divinyl sebacate in anhydrous pyridine at 50 ℃ for 6 d was catalyzed by an alkaline protease from Bacillus subtilis. Three raffinose vinyl esters with different acyl donor chain lengths were regioselectively synthesized at 55%, 48% and 30% yields, respectively. Characterization of the products by 1H NMR, 13C NMR, and 1H- 1H correlation spectroscopy and 1H- 13C heteronuclear multiple quantum coherence NMR revealed that the ester was substituted at C-1 position of β-fructofuranose moiety in raffinose. Reaction conditions for the esterification were investigated. Activities of seven commercial enzymes from different sources catalyzing synthesis of raffinose ester were compared. Lipase from porcine pancreas(PPL) and alkaline protease from Bacillus subtilis had high activities. We also studied the effect of temperature and incubation time on raffinose esters synthesis catalyzed by alkaline protease from Bacillus subtilis and found the optimal temperature and reaction time were 50 ℃ and 6 d respectively.