• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemistry: A European journal >Aldol Additions of Dihydroxyacetone Phosphate to N-Cbz-Amino Aldehydes Catalyzed by L-Fuculose-1-Phosphate Aldolase in Emulsion Systems:Inversion of Stereoselectivity as a Function of the Acceptor Aldehyde
【24h】

Aldol Additions of Dihydroxyacetone Phosphate to N-Cbz-Amino Aldehydes Catalyzed by L-Fuculose-1-Phosphate Aldolase in Emulsion Systems:Inversion of Stereoselectivity as a Function of the Acceptor Aldehyde

机译：乳液体系中L-富糖1-磷酸醛缩酶催化N-Cbz-氨基醛缩醛中磷酸二羟丙酮的醛醇加成反应：立体选择性随受体醛的变化

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The potential of L-fuculose-1-phosphate aldolase (FucA) as a catalyst for the asymmetric aldol addition of dihydroxyacetone phosphate (DHAP) to N-protected amino aldehydes has been investigated.First,the reaction was studied in both emulsion systems and conventional dimethylform-amide (DMF)/H_2O (1:4 v/v) mixtures.At 100 mM DHAP,compared with the reactions in the DMF/H_2O (1:4) mixture,the use of emulsion systems led to two- to three-fold improvements in the conversions of the FucA-catalyzed reactions.The N-protected aminopolyols thus obtained were converted to imino-cyclitols by reductive amination with Pd/C.This reaction was highly diaster-eoselective with the exception of the reaction of the aldol adduct formed from (S)-N-Cbz-alaninal,which gave a 55:45 mixture of both epimers.From the stereochemical analysis of the resulting iminocyclitols,it was concluded that the Stereoselectivity of the FucA-catalyzed reaction depended upon the structure of the N-Cbz-amino aldehyde acceptor.Whereas the enzymatic aldol reaction with both enantiomers of N-Cbz-alaninal exclusively gave the expected 3R,4R configuration,the stereochemistry at the C-4 position of the major aldol adducts produced in the reactions with N-Cbz-glycinal and N-Cbz-3-aminopropanal was inverted to the 3R,4S configuration.The study of the FucA-catalyzed addition of DHAP to phenylacetaldehyde and benzyloxya-cetaldehyde revealed that the 4R product was kinetically favored,but rapidly disappeared in favor of the 45 diaster-eoisomer.Computational models were generated for the situations before and after C-C bond formation in the active site of FucA.Moreover,the lowest-energy conformations of each pair of the resulting epimeric adducts were determined.The data show that the products with a 3R,4S configuration were thermodynamically more stable and,therefore,the major products formed,in agreement with the experimental results.
机译：研究了L-岩藻糖-1-磷酸醛缩酶（FucA）作为不对称醛缩醛磷酸酯（DHAP）向N保护的氨基醛中不对称醛缩醛加成催化剂的潜力。首先，在乳液体系和常规体系中研究了该反应。二甲基甲酰胺（DMF）/ H_2O（1：4 v / v）混合物。在100 mM DHAP下，与DMF / H_2O（1：4）混合物中的反应相比，乳液体系的使用导致两到三FucA催化反应的转化率提高了三倍。由此获得的N-保护的氨基多元醇通过Pd / C的还原胺化反应转变为亚氨基环糖醇。该反应除醛醇缩合反应外，具有高度的非对映选择性。由（S）-N-Cbz-丙氨酸形成的加合物，可得到两种差向异构体的55:45混合物。对所得亚氨基环糖醇的立体化学分析表明，FucA催化反应的立体选择性取决于甲壳素的结构。 N-Cbz-氨基醛受体与N-Cbz-丙氨酸的两个对映异构体的酶促醛醇缩合反应仅给出预期的3R，4R构型，在与N-Cbz-glycinal和N-Cbz的反应中生成的主要醛醇加合物的C-4位置的立体化学-3-氨基丙醛被转化为3R，4S构型。FucA催化将DHAP加到苯乙醛和苄氧基乙醛中的研究表明，4R产物在动力学上是有利的，但很快就消失了，成为45非对映异构体。针对FucA活性位点CC键形成前后的情况建立了计算模型。此外，确定了每对所得的差向异构加合物的最低能量构象。数据表明具有3R，4S构型的产物热力学上更稳定，因此形成了主要产物，与实验结果一致。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号