Catalyst recognition of cis-1,2-diols enables site-selective functionalization of complex molecules
作者:Xixi Sun、Hyelee Lee、Sunggi Lee、Kian L. Tan
DOI:10.1038/nchem.1726
日期:2013.9
Carbohydrates and natural products serve essential roles in nature, and also provide core scaffolds for pharmaceutical agents and vaccines. However, the inherent complexity of these molecules imposes significant synthetic hurdles for their selective functionalization and derivatization. Nature has, in part, addressed these issues by employing enzymes that are able to orient and activate substrates within a chiral pocket, which increases dramatically both the rate and selectivity of organic transformations. In this article we show that similar proximity effects can be utilized in the context of synthetic catalysts to achieve general and predictable site-selective functionalization of complex molecules. Unlike enzymes, our catalysts apply a single reversible covalent bond to recognize and bind to specific functional group displays within substrates. By combining this unique binding selectivity and asymmetric catalysis, we are able to modify the less reactive axial positions within monosaccharides and natural products. The manipulation of complex molecules offers an avenue for developing new therapeutics and biological probes. Here, a catalyst is described that forms a covalent bond to the substrate before selectively functionalizing a proximal functional group. Cis-1,2-diols are targeted allowing for the derivatization of the axial hydroxyls of monosaccharides in the presence of unprotected equatorial hydroxyls.
碳水化合物和天然产物在自然界中扮演着重要角色,并为制药剂和疫苗提供了核心骨架。然而,这些分子的固有复杂性给其选择性功能化和衍生化带来了重大的合成挑战。自然界在一定程度上通过利用酶来解决这些问题,这些酶能够在手性口袋中定向和激活底物,从而显著提高有机转化的速率和选择性。本文展示了,在合成催化剂的情境下,类似的接近效应也可以被利用来实现复杂分子的一般性和可预测的位点选择性功能化。与酶不同,我们的催化剂采用单一的可逆共价键来识别和结合底物中的特定功能基团。通过结合这种独特的结合选择性和不对称催化,我们能够修饰单糖和天然产品中较不活跃的轴向位置。复杂分子的操作为开发新的治疗药物和生物探针提供了途径。这里描述了一种催化剂,它在与底物形成共价键后,选择性地功能化邻近的功能基团。目标为顺-1,2-二醇,允许在未保护的赤道羟基存在下衍生化单糖的轴向羟基。