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首页> 外文期刊>Chemistry: A European journal >Amino acid catalyzed neogenesis of carbohydrates: A plausible ancient transformation
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Amino acid catalyzed neogenesis of carbohydrates: A plausible ancient transformation

机译：氨基酸催化碳水化合物的新生：似乎是古老的转变

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Hexose sugars play a fundamental role in vital biochemical processes and their biosynthesis is achieved through enzyme-catalyzed pathways. Herein we disclose the ability of amino acids to catalyze the asymmetric neogenesis of carbohydrates by sequential cross-aldol reactions. The amino acids mediate the asymmetric de novo synthesis of natural L- and D-hexoses and their analogues with excellent stereoselectivity in organic solvents. In some cases, the four new stereocenters are assembled with almost absolute stereo-control. The unique feature of these results is that, when an amino acid is employed as the catalyst, a single reaction sequence can convert a protected glycol aldehyde into a hexose in one step. For example, proline and its derivatives catalyze the asymmetric neo-genesis of allose with < 99% ee in one chemical manipulation. Furthermore. all amino acids tested catalyzed the asymmetric formation of natural sugars under prebiotic conditions with alanine being the smallest catalyst. The inherent simplicity of this catalytic process suggests that a catalytic prebiotic 'gluconeogenesis" may occur in which amino acids transfer their stereochemical information to sugars. In addition. the amino acid catalyzed stercoselective sequential cross-aldol reactions were performed as a two-step procedure with different aldehydes as acceptors acceptors and nucleophiles. The employment of two different amino acids as catalysts for the iterative direct aldol reaction enabled the asymmetric synthesis of deoxysugars with > 99% ee. In addition. the direct amino acid catalyzed C-2+C-2+C-2 methodology is a new entry for the short, highly enantioselective de novo synthesis of carbohydrate derivatives. isotope-labeled sugars, and polykelide natural products, The one-pot asymmetric de novo syntheses of deoxy and polyketide carbohydrates involved a novel dynamic kinetic asymmetric transformation (DYKAT) mediated by an amino acid.
机译：己糖在重要的生化过程中起着基本作用，其生物合成是通过酶催化的途径实现的。本文中，我们公开了氨基酸通过顺序的交叉醛醇缩合反应催化碳水化合物的不对称新生的能力。氨基酸介导天然L-和D-己糖及其类似物的不对称从头合成，在有机溶剂中具有出色的立体选择性。在某些情况下，四个新的立体声中心的组装几乎具有绝对的立体声控制。这些结果的独特之处在于，当将氨基酸用作催化剂时，单个反应序列可以一步将受保护的乙二醇醛转化为己糖。例如，脯氨酸及其衍生物在一种化学操作中催化ee小于99％的Allose的不对称新生成。此外。在益生元条件下，所有测试的氨基酸都催化天然糖的不对称形成，其中丙氨酸是最小的催化剂。该催化过程固有的简单性表明，可能发生催化的益生元“糖异生”，其中氨基酸将其立体化学信息转移到糖上，此外，氨基酸催化的固醇选择性顺序交叉羟醛反应以两步程序进行，不同的醛作为受体和亲核试剂，使用两种不同的氨基酸作为迭代直接羟醛反应的催化剂，可以不对称合成ee> 99％ee的脱氧糖，此外，直接氨基酸催化的C-2 + C-2 + C-2方法学是对碳水化合物衍生物，同位素标记的糖和聚醚类天然产物进行短而高度对映选择性从头合成的新方法。一锅脱氧和聚酮化合物碳水化合物的不对称从头合成涉及一种新颖的动力学氨基酸介导的不对称转化（DYKAT）。

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