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.
By this method, diols and polyols are regioselectively acetylated in high yields under mild conditions using catalyticamounts of acetate. In comparison to other methods involving reagents such as organotin, organoboron, organosilicon, organobase, and metal salts, this method is more environmentally friendly, convenient, and efficient and is also associated with higher regioselectivity. We have performed
An inexpensive catalyst, Fe(acac)<sub>3</sub>, for regio/site-selective acylation of diols and carbohydrates containing a 1,2-<i>cis</i>-diol
作者:Jian Lv、Jian-Tao Ge、Tao Luo、Hai Dong
DOI:10.1039/c8gc00428e
日期:——
This work describes the [Fe(acac)3] (acac = acetylacetonate)-catalyzed, regio/site-selective acylation of 1,2- and 1,3-diols and glycosides containing a cis-vicinal diol. The iron(III) catalysts initially formed cyclic dioxolane-type intermediates with substrates between the iron(III) species and vicinal diols, and the efficient and selective acylation of one hydroxyl group was subsequently achieved
The 1,5‐diazabicyclo[4.3.0]non‐5‐ene (DBN)‐catalyzed, highly efficient and relatively green regioselective acylation of carbohydrates and diols is firstly developed. The hydroxyl groups can be selectively acylated by the corresponding anhydride in EtOAc in the presence of a catalyticamount (as low as 0.1 equiv.) of DBN at room temperature to 40 °C.
Diisopropylethylamine-triggered, highly efficient, self-catalyzed regioselective acylation of carbohydrates and diols
作者:Bo Ren、Lu Gan、Li Zhang、Ningning Yan、Hai Dong
DOI:10.1039/c8ob01464g
日期:——
diisopropylethylamine (DIPEA)-triggered, self-catalyzed, regioselective acylation of carbohydrates and diols is presented. The hydroxyl groups can be acylated by the corresponding anhydride in MeCN in the presence of a catalytic amount of DIPEA. This method is comparatively green and mild as it uses less organic base compared with other selective acylationmethods. Mechanistic studies indicate that DIPEA reacts with