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.